more house keeping

ARCHITECTURE.md

@@ -1,409 +0,0 @@
-## JormunDB Architecture
-# !!THIS IS NO LONGER ENTIRELY ACCURATE IGNORE OR UPDATE WITH ACCURATE INFO!!
-
-This document explains the internal architecture of JormunDB, including design decisions, storage formats, and the arena-per-request memory management pattern.
-
-## Table of Contents
-
-- [Overview](#overview)
-- [Why Odin?](#why-odin)
-- [Memory Management](#memory-management)
-- [Storage Format](#storage-format)
-- [Module Structure](#module-structure)
-- [Request Flow](#request-flow)
-- [Concurrency Model](#concurrency-model)
-
-## Overview
-
-JormunDB is a DynamoDB-compatible database server that speaks the DynamoDB wire protocol. It uses RocksDB for persistent storage and is written in Odin for elegant memory management.
-
-### Key Design Goals
-
-1. **Zero allocation ceremony** - No explicit `defer free()` or error handling for every allocation
-2. **Binary storage** - Efficient TLV encoding instead of JSON
-3. **API compatibility** - Drop-in replacement for DynamoDB
-4. **Performance** - RocksDB-backed with efficient key encoding
-
-## Why Odin?
-
-The original implementation in Zig suffered from explicit allocator threading:
-
-```zig
-// Zig version - explicit allocator everywhere
-fn handleRequest(allocator: std.mem.Allocator, request: []const u8) !Response {
-    const parsed = try parseJson(allocator, request);
-    defer parsed.deinit(allocator);
-
-    const item = try storage.getItem(allocator, parsed.table_name, parsed.key);
-    defer if (item) |i| freeItem(allocator, i);
-
-    const response = try serializeResponse(allocator, item);
-    defer allocator.free(response);
-
-    return response; // Wait, we deferred the free!
-}
-```
-
-Odin's context allocator system eliminates this:
-
-```odin
-// Odin version - implicit context allocator
-handle_request :: proc(request: []byte) -> Response {
-    // All allocations use context.allocator automatically
-    parsed := parse_json(request)
-    item := storage_get_item(parsed.table_name, parsed.key)
-    response := serialize_response(item)
-
-    return response
-    // Everything freed when arena is destroyed
-}
-```
-
-## Memory Management
-
-JormunDB uses a two-allocator strategy:
-
-### 1. Arena Allocator (Request-Scoped)
-
-Every HTTP request gets its own arena:
-
-```odin
-handle_connection :: proc(conn: net.TCP_Socket) {
-    // Create arena for this request (4MB)
-    arena: mem.Arena
-    mem.arena_init(&arena, make([]byte, mem.Megabyte * 4))
-    defer mem.arena_destroy(&arena)
-
-    // Set context allocator
-    context.allocator = mem.arena_allocator(&arena)
-
-    // All downstream code uses context.allocator
-    request := parse_http_request(conn)    // uses arena
-    response := handle_request(request)     // uses arena
-    send_response(conn, response)           // uses arena
-
-    // Arena is freed here - everything cleaned up automatically
-}
-```
-
-**Benefits:**
-- No individual `free()` calls needed
-- No `errdefer` cleanup
-- No use-after-free bugs
-- No memory leaks from forgotten frees
-- Predictable performance (no GC pauses)
-
-### 2. Default Allocator (Long-Lived Data)
-
-The default allocator (typically `context.allocator` at program start) is used for:
-
-- Table metadata
-- Table locks (sync.RW_Mutex)
-- Engine state
-- Items returned from storage layer (copied to request arena when needed)
-
-## Storage Format
-
-### Binary Keys (Varint-Prefixed Segments)
-
-All keys use varint length prefixes for space efficiency:
-
-```
-Meta key:  [0x01][len][table_name]
-Data key:  [0x02][len][table_name][len][pk_value][len][sk_value]?
-GSI key:   [0x03][len][table_name][len][index_name][len][gsi_pk][len][gsi_sk]?
-LSI key:   [0x04][len][table_name][len][index_name][len][pk][len][lsi_sk]
-```
-
-**Example Data Key:**
-```
-Table: "Users"
-PK: "user:123"
-SK: "profile"
-
-Encoded:
-[0x02]          // Entity type (Data)
-[0x05]          // Table name length (5)
-Users           // Table name bytes
-[0x08]          // PK length (8)
-user:123        // PK bytes
-[0x07]          // SK length (7)
-profile         // SK bytes
-```
-
-### Item Encoding (TLV Format)
-
-Items use Tag-Length-Value encoding for space efficiency:
-
-```
-Format:
-[attr_count:varint]
-  [name_len:varint][name:bytes][type_tag:u8][value_len:varint][value:bytes]...
-
-Type Tags:
-  String  = 0x01    Number = 0x02    Binary = 0x03
-  Bool    = 0x04    Null   = 0x05
-  SS      = 0x10    NS     = 0x11    BS     = 0x12
-  List    = 0x20    Map    = 0x21
-```
-
-**Example Item:**
-```json
-{
-  "id": {"S": "user123"},
-  "age": {"N": "30"}
-}
-```
-
-Encoded as:
-```
-[0x02]              // 2 attributes
-  [0x02]            // name length (2)
-  id                // name bytes
-  [0x01]            // type tag (String)
-  [0x07]            // value length (7)
-  user123           // value bytes
-
-  [0x03]            // name length (3)
-  age               // name bytes
-  [0x02]            // type tag (Number)
-  [0x02]            // value length (2)
-  30                // value bytes (stored as string)
-```
-
-## Request Flow
-
-```
-1. HTTP POST / arrives
-   ↓
-2. Create arena allocator (4MB)
-   Set context.allocator = arena_allocator
-   ↓
-3. Parse HTTP headers
-   Extract X-Amz-Target → Operation
-   ↓
-4. Parse JSON body
-   Convert DynamoDB JSON → internal types
-   ↓
-5. Route to handler (e.g., handle_put_item)
-   ↓
-6. Storage engine operation
-   - Build binary key
-   - Encode item to TLV
-   - RocksDB put/get/delete
-   ↓
-7. Build response
-   - Serialize item to DynamoDB JSON
-   - Format HTTP response
-   ↓
-8. Send response
-   ↓
-9. Destroy arena
-   All request memory freed automatically
-```
-
-## Concurrency Model
-
-### Table-Level RW Locks
-
-Each table has a reader-writer lock:
-
-```odin
-Storage_Engine :: struct {
-    db:                 rocksdb.DB,
-    table_locks:        map[string]^sync.RW_Mutex,
-    table_locks_mutex:  sync.Mutex,
-}
-```
-
-**Read Operations** (GetItem, Query, Scan):
-- Acquire shared lock
-- Multiple readers can run concurrently
-- Writers are blocked
-
-**Write Operations** (PutItem, DeleteItem, UpdateItem):
-- Acquire exclusive lock
-- Only one writer at a time
-- All readers are blocked
-
-### Thread Safety
-
-- RocksDB handles are thread-safe (column family-based)
-- Table metadata is protected by locks
-- Request arenas are thread-local (no sharing)
-
-## Error Handling
-
-Odin uses explicit error returns via `or_return`:
-
-```odin
-// Odin error handling
-parse_json :: proc(data: []byte) -> (Item, bool) {
-    parsed := json.parse(data) or_return
-    item := json_to_item(parsed) or_return
-    return item, true
-}
-
-// Usage
-item := parse_json(request.body) or_else {
-    return error_response(.ValidationException, "Invalid JSON")
-}
-```
-
-No exceptions, no panic-recover patterns. Every error path is explicit.
-
-## DynamoDB Wire Protocol
-
-### Request Format
-
-```
-POST / HTTP/1.1
-X-Amz-Target: DynamoDB_20120810.PutItem
-Content-Type: application/x-amz-json-1.0
-
-{
-  "TableName": "Users",
-  "Item": {
-    "id": {"S": "user123"},
-    "name": {"S": "Alice"}
-  }
-}
-```
-
-### Response Format
-
-```
-HTTP/1.1 200 OK
-Content-Type: application/x-amz-json-1.0
-x-amzn-RequestId: local-request-id
-
-{}
-```
-
-### Error Format
-
-```json
-{
-  "__type": "com.amazonaws.dynamodb.v20120810#ResourceNotFoundException",
-  "message": "Table not found"
-}
-```
-
-## Performance Characteristics
-
-### Time Complexity
-
-| Operation | Complexity | Notes |
-|-----------|-----------|-------|
-| PutItem | O(log n) | RocksDB LSM tree insert |
-| GetItem | O(log n) | RocksDB point lookup |
-| DeleteItem | O(log n) | RocksDB deletion |
-| Query | O(log n + m) | n = items in table, m = result set |
-| Scan | O(n) | Full table scan |
-
-### Space Complexity
-
-- Binary keys: ~20-100 bytes (vs 50-200 bytes JSON)
-- Binary items: ~30% smaller than JSON
-- Varint encoding saves space on small integers
-
-### Benchmarks (Expected)
-
-Based on Zig version performance:
-
-```
-Operation          Throughput      Latency (p50)
-PutItem            ~5,000/sec      ~0.2ms
-GetItem            ~7,000/sec      ~0.14ms
-Query (1 item)     ~8,000/sec      ~0.12ms
-Scan (1000 items)  ~20/sec         ~50ms
-```
-
-## Future Enhancements
-
-### Planned Features
-
-1. **UpdateExpression** - SET/REMOVE/ADD/DELETE operations
-2. **FilterExpression** - Post-query filtering
-3. **ProjectionExpression** - Return subset of attributes
-4. **Global Secondary Indexes** - Query by non-key attributes
-5. **Local Secondary Indexes** - Alternate sort keys
-6. **BatchWriteItem** - Batch mutations
-7. **BatchGetItem** - Batch reads
-8. **Transactions** - ACID multi-item operations
-
-### Optimization Opportunities
-
-1. **Connection pooling** - Reuse HTTP connections
-2. **Bloom filters** - Faster negative lookups
-3. **Compression** - LZ4/Zstd on large items
-4. **Caching layer** - Hot item cache
-5. **Parallel scan** - Segment-based scanning
-
-## Debugging
-
-### Enable Verbose Logging
-
-```bash
-make run VERBOSE=1
-```
-
-### Inspect RocksDB
-
-```bash
-# Use ldb tool to inspect database
-ldb --db=./data scan
-ldb --db=./data get <key_hex>
-```
-
-### Memory Profiling
-
-Odin's tracking allocator can detect leaks:
-
-```odin
-when ODIN_DEBUG {
-    track: mem.Tracking_Allocator
-    mem.tracking_allocator_init(&track, context.allocator)
-    context.allocator = mem.tracking_allocator(&track)
-
-    defer {
-        for _, leak in track.allocation_map {
-            fmt.printfln("Leaked %d bytes at %p", leak.size, leak.location)
-        }
-    }
-}
-```
-
-## Migration from Zig Version
-
-The Zig version (ZynamoDB) used the same binary storage format, so existing RocksDB databases can be read by JormunDB without migration.
-
-### Compatibility
-
-- ✅ Binary key format (byte-compatible)
-- ✅ Binary item format (byte-compatible)
-- ✅ Table metadata (JSON, compatible)
-- ✅ HTTP wire protocol (identical)
-
-### Breaking Changes
-
-None - JormunDB can open ZynamoDB databases directly.
-
----
-
-## Contributing
-
-When contributing to JormunDB:
-
-1. **Use the context allocator** - All request-scoped allocations should use `context.allocator`
-2. **Avoid manual frees** - Let the arena handle it
-3. **Long-lived data** - Use the default allocator explicitly
-4. **Test thoroughly** - Run `make test` before committing
-5. **Format code** - Run `make fmt` before committing
-
-## References
-
-- [Odin Language](https://odin-lang.org/)
-- [RocksDB Wiki](https://github.com/facebook/rocksdb/wiki)
-- [DynamoDB API Reference](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/)
-- [Varint Encoding](https://developers.google.com/protocol-buffers/docs/encoding#varints)

Makefile

@@ -1,4 +1,4 @@
-.PHONY: all build release run test clean fmt help install sdk_test
+.PHONY: all build release run test clean fmt help install
 
 # Project configuration
 PROJECT_NAME := jormundb
@@ -147,42 +147,6 @@ check-deps:
 	@pkg-config --exists rocksdb || (echo "$(RED)✗ RocksDB not found$(NC)" && exit 1)
 	@echo "$(GREEN)✓ All dependencies found$(NC)"
 
-# AWS CLI test commands
-aws-test: run &
-	@sleep 2
-	@echo "$(BLUE)Testing with AWS CLI...$(NC)"
-	@echo "\n$(YELLOW)Creating table...$(NC)"
-	@aws dynamodb create-table \
-		--endpoint-url http://localhost:$(PORT) \
-		--table-name TestTable \
-		--key-schema AttributeName=pk,KeyType=HASH \
-		--attribute-definitions AttributeName=pk,AttributeType=S \
-		--billing-mode PAY_PER_REQUEST || true
-	@echo "\n$(YELLOW)Listing tables...$(NC)"
-	@aws dynamodb list-tables --endpoint-url http://localhost:$(PORT)
-	@echo "\n$(YELLOW)Putting item...$(NC)"
-	@aws dynamodb put-item \
-		--endpoint-url http://localhost:$(PORT) \
-		--table-name TestTable \
-		--item '{"pk":{"S":"test1"},"data":{"S":"hello world"}}'
-	@echo "\n$(YELLOW)Getting item...$(NC)"
-	@aws dynamodb get-item \
-		--endpoint-url http://localhost:$(PORT) \
-		--table-name TestTable \
-		--key '{"pk":{"S":"test1"}}'
-	@echo "\n$(YELLOW)Scanning table...$(NC)"
-	@aws dynamodb scan \
-		--endpoint-url http://localhost:$(PORT) \
-		--table-name TestTable
-	@echo "\n$(GREEN)✓ AWS CLI test complete$(NC)"
-
-# Python SDK integration tests (requires JormunDB running on localhost)
-sdk_test:
-	@echo "$(BLUE)Running Python SDK tests against localhost:$(PORT)...$(NC)"
-	@docker compose -f $(SDK_TEST_COMPOSE) down --remove-orphans 2>/dev/null || true
-	@JORMUN_PORT=$(PORT) docker compose -f $(SDK_TEST_COMPOSE) run --rm --build sdk-test
-	@docker compose -f $(SDK_TEST_COMPOSE) down --remove-orphans 2>/dev/null || true
-
 # Development workflow
 dev: clean build run
 
@@ -207,8 +171,6 @@ help:
 	@echo ""
 	@echo "$(GREEN)Test Commands:$(NC)"
 	@echo "  make test           - Run unit tests"
-	@echo "  make aws-test       - Test with AWS CLI commands"
-	@echo "  make sdk_test       - Run Python SDK integration tests (requires running server)"
 	@echo ""
 	@echo "$(GREEN)Utility Commands:$(NC)"
 	@echo "  make fmt            - Format source code"

QUICKSTART.md

@@ -404,7 +404,6 @@ brew upgrade odin  # macOS
 
 ## Next Steps
 
-- Read [ARCHITECTURE.md](ARCHITECTURE.md) for internals
 - Check [TODO.md](TODO.md) for implementation status
 - Browse source code in `dynamodb/`, `rocksdb/`, etc.
 

README.md

@@ -189,16 +189,38 @@ make run PORT=9000 DATA_DIR=/tmp/db VERBOSE=1
 
 ## Performance
 
-From benchmarks on the original Zig version (Odin expected to be similar or better):
+Benchmarked on single node localhost, 1000 iterations per test.
 
-```
-Sequential Writes     |      10000 ops |   245.32 ms |    40765 ops/sec
-Random Reads          |      10000 ops |   312.45 ms |    32006 ops/sec
-Batch Writes          |      10000 ops |    89.23 ms |   112071 ops/sec
-PutItem               |       5000 ops |   892.34 ms |     5604 ops/sec
-GetItem               |       5000 ops |   678.91 ms |     7365 ops/sec
-Scan (full table)     |       5000 ops |   234.56 ms |    21320 ops/sec
-```
+### Basic Operations
+
+| Operation | Throughput | Avg Latency | P95 Latency | P99 Latency |
+|-----------|------------|-------------|-------------|-------------|
+| **PutItem** | 1,021 ops/sec | 0.98ms | 1.02ms | 1.64ms |
+| **GetItem** | 1,207 ops/sec | 0.83ms | 0.90ms | 1.14ms |
+| **Query** | 1,002 ops/sec | 1.00ms | 1.11ms | 1.85ms |
+| **Scan** (100 items) | 18,804 ops/sec | 0.05ms | - | - |
+| **DeleteItem** | 1,254 ops/sec | 0.80ms | - | - |
+
+### Batch Operations
+
+| Operation | Throughput | Batch Size |
+|-----------|------------|------------|
+| **BatchWriteItem** | 9,297 ops/sec | 25 items |
+| **BatchGetItem** | 9,113 ops/sec | 25 items |
+
+### Concurrent Operations
+
+| Workers | Throughput | Avg Latency | P95 Latency | P99 Latency |
+|---------|------------|-------------|-------------|-------------|
+| **10 concurrent** | 1,286 ops/sec | 7.70ms | 15.16ms | 19.72ms |
+
+### Large Payloads
+
+| Payload Size | Throughput | Avg Latency |
+|--------------|------------|-------------|
+| **10KB** | 522 ops/sec | 1.91ms |
+| **50KB** | 166 ops/sec | 6.01ms |
+| **100KB** | 96 ops/sec | 10.33ms |
 
 ## API Compatibility
 
@@ -218,11 +240,11 @@ Scan (full table)     |       5000 ops |   234.56 ms |    21320 ops/sec
 - ✅ ProjectionExpression
 - ✅ BatchWriteItem
 - ✅ BatchGetItem
+- ✅ Global Secondary Indexes
 
 ### Coming Soon
 
 - ⏳ UpdateItem (works but needs UPDATED_NEW/UPDATED_OLD response filtering to work for full Dynamo Parity)
-- ⏳ Global Secondary Indexes
 - ⏳ Local Secondary Indexes
 
 ## Configuration

TODO.md

@@ -8,7 +8,7 @@ Goal: "aws cli works reliably for CreateTable/ListTables/PutItem/GetItem/DeleteI
 
 ### 1) HTTP + routing hardening
 - [ ] Audit request parsing boundaries:
-  - Max body size enforcement (config exists, need to verify enforcement path)
+  - Max body size enforcement — **DONE**
   - Missing/invalid headers → correct DynamoDB error types
   - Content-Type handling (be permissive but consistent)
 - [x] Ensure **all request-scoped allocations** come from the request arena (no accidental long-lived allocs)

docker-compose-python-sdk-test.yaml

@@ -1,14 +0,0 @@
-services:
-  sdk-test:
-    image: python:3.12-slim
-    network_mode: host
-    working_dir: /tests
-    volumes:
-      - ./tests/sdk:/tests
-    environment:
-      - JORMUN_ENDPOINT=http://localhost:${JORMUN_PORT:-8002}
-      - AWS_ACCESS_KEY_ID=local
-      - AWS_SECRET_ACCESS_KEY=local
-      - AWS_DEFAULT_REGION=us-east-1
-    command: >
-      sh -c "pip install --quiet boto3 && python test_sdk.py"

dynamodb/batch.odin

@@ -65,6 +65,17 @@ batch_write_item :: proc(
 		unprocessed = make([dynamic]Batch_Write_Table_Request),
 	}
 
+	// Count total operations across all tables
+	total_ops := 0
+	for table_req in table_requests {
+		total_ops += len(table_req.requests)
+	}
+
+	// Enforce DynamoDB limit: 25 operations per batch
+	if total_ops > 25 {
+		return result, .Validation_Error
+	}
+
 	for table_req in table_requests {
 		failed_requests := make([dynamic]Write_Request)
 
@@ -78,13 +89,38 @@ batch_write_item :: proc(
 				var_err = delete_item(engine, table_req.table_name, req.item)
 			}
 
+			// Distinguish validation errors from transient failures
 			if var_err != .None {
-				// Deep copy the failed request for UnprocessedItems
-				failed_item := item_deep_copy(req.item)
-				append(&failed_requests, Write_Request{
-					type = req.type,
-					item = failed_item,
-				})
+				#partial switch var_err {
+				case .Missing_Key_Attribute, .Invalid_Key, .Serialization_Error:
+					// Hard validation errors — fail the entire batch
+					batch_write_result_destroy(&result)
+					delete(failed_requests)
+					return result, var_err
+
+				case .Table_Not_Found:
+					// Non-existent table is a hard request failure, not a retryable condition.
+					// DynamoDB returns ResourceNotFoundException for the whole request.
+					batch_write_result_destroy(&result)
+					delete(failed_requests)
+					return result, .Table_Not_Found
+
+				case .RocksDB_Error, .Item_Not_Found:
+					// Genuinely transient/infrastructure errors — add to UnprocessedItems.
+					failed_item := item_deep_copy(req.item)
+					append(&failed_requests, Write_Request{
+						type = req.type,
+						item = failed_item,
+					})
+
+				case .None, .Validation_Error, .Internal_Error:
+					// Should not happen, but handle gracefully
+					failed_item := item_deep_copy(req.item)
+					append(&failed_requests, Write_Request{
+						type = req.type,
+						item = failed_item,
+					})
+				}
 			}
 		}
 
@@ -101,6 +137,7 @@ batch_write_item :: proc(
 	return result, .None
 }
 
+
 // ============================================================================
 // BatchGetItem Types
 // ============================================================================
@@ -157,6 +194,17 @@ batch_get_item :: proc(
 		unprocessed_keys = make([dynamic]Batch_Get_Table_Request),
 	}
 
+	// Count total keys across all tables
+	total_keys := 0
+	for table_req in table_requests {
+		total_keys += len(table_req.keys)
+	}
+
+	// Enforce DynamoDB limit: 100 keys per batch
+	if total_keys > 100 {
+		return result, .Validation_Error
+	}
+
 	for table_req in table_requests {
 		found_items := make([dynamic]Item)
 		failed_keys := make([dynamic]Item)
@@ -164,10 +212,25 @@ batch_get_item :: proc(
 		for key in table_req.keys {
 			item_result, get_err := get_item(engine, table_req.table_name, key)
 
+			// Distinguish validation errors from transient failures
 			if get_err != .None && get_err != .Item_Not_Found {
-				// Storage error — add to unprocessed
-				append(&failed_keys, item_deep_copy(key))
-				continue
+				#partial switch get_err {
+				case .Missing_Key_Attribute, .Invalid_Key, .Serialization_Error:
+					// Hard validation error — fail the entire batch
+					batch_get_result_destroy(&result)
+					delete(found_items)
+					delete(failed_keys)
+					return result, get_err
+
+				case .RocksDB_Error, .Table_Not_Found:
+					// Transient error — add to unprocessed
+					append(&failed_keys, item_deep_copy(key))
+					continue
+
+				case .None, .Validation_Error, .Internal_Error, .Item_Not_Found:
+					// Should not happen here, but handle gracefully
+					continue
+				}
 			}
 
 			if item_val, has_item := item_result.?; has_item {

dynamodb/condition.odin

@@ -16,6 +16,7 @@
 package dynamodb
 
 import "core:encoding/json"
+import "core:strings"
 
 // ============================================================================
 // Condition Evaluation Result
@@ -54,7 +55,7 @@ parse_condition_expression_string :: proc(request_body: []byte) -> (expr: string
 		return
 	}
 
-	expr = string(ce_str)
+	expr = strings.clone(string(ce_str))
 	ok = true
 	return
 }
@@ -88,6 +89,7 @@ evaluate_condition_expression :: proc(
 	if !has_condition {
 		return .Passed // No condition → always pass
 	}
+	defer delete(condition_str)
 
 	// Parse the condition into a filter tree (same grammar as FilterExpression)
 	filter_node, parse_ok := parse_filter_expression(condition_str, attr_names, attr_values)

dynamodb/expression.odin

@@ -60,8 +60,9 @@ key_condition_get_pk_bytes :: proc(kc: ^Key_Condition) -> ([]byte, bool) {
 	#partial switch v in kc.pk_value {
 	case String:
 		return transmute([]byte)string(v), true
-	case Number:
-		return transmute([]byte)string(v), true
+	case DDB_Number:
+		// Use canonical encoding for numbers in keys!
+		return encode_ddb_number_for_sort(v), true
 	case Binary:
 		return transmute([]byte)string(v), true
 	}
@@ -110,7 +111,7 @@ tokenizer_next :: proc(t: ^Tokenizer) -> Maybe(string) {
 	}
 
 	// Single-character operators
-	if c == '=' || c == '<' || c == '>' {
+	if c == '=' || c == '<' || c == '>' || c == '+' || c == '-' {
 		t.pos += 1
 		return t.input[start:t.pos]
 	}
@@ -137,9 +138,9 @@ is_whitespace :: proc(c: byte) -> bool {
 @(private = "file")
 is_ident_char :: proc(c: byte) -> bool {
 	return (c >= 'a' && c <= 'z') ||
-	       (c >= 'A' && c <= 'Z') ||
-	       (c >= '0' && c <= '9') ||
-	       c == '_' || c == ':' || c == '#' || c == '-' || c == '.'
+			(c >= 'A' && c <= 'Z') ||
+			(c >= '0' && c <= '9') ||
+			c == '_' || c == ':' || c == '#' || c == '.'
 }
 
 // ---------------------------------------------------------------------------
@@ -173,12 +174,14 @@ parse_key_condition_expression :: proc(
 
 	eq_token := next_token(&t) or_return
 	if eq_token != "=" {
+		delete(pk_name) // free on error
 		return
 	}
 
 	pk_value_token := next_token(&t) or_return
 	pk_value, pk_ok := resolve_attribute_value(pk_value_token, attribute_values)
 	if !pk_ok {
+		delete(pk_name) // free on error
 		return
 	}
 
@@ -187,18 +190,30 @@ parse_key_condition_expression :: proc(
 	// Optional "AND ..."
 	if and_token, has_and := tokenizer_next(&t).?; has_and {
 		if !strings.equal_fold(and_token, "AND") {
+			delete(pk_name) // free on error
 			attr_value_destroy(&pk_value)
 			return
 		}
 
 		skc, skc_ok := parse_sort_key_condition(&t, attribute_names, attribute_values)
 		if !skc_ok {
+			delete(pk_name) // free on error
 			attr_value_destroy(&pk_value)
 			return
 		}
 		sk_condition = skc
 	}
 
+	// Verify all tokens were consumed (no trailing garbage)
+	if trailing := tokenizer_next(&t); trailing != nil {
+		delete(pk_name)
+		attr_value_destroy(&pk_value)
+		if skc, has_skc := sk_condition.?; has_skc {
+			skc_copy := skc
+			sort_key_condition_destroy(&skc_copy)
+		}
+		return
+	}
 
 	kc = Key_Condition{
 		pk_name      = pk_name,
@@ -228,12 +243,14 @@ parse_sort_key_condition :: proc(
 	op_token := next_token(t) or_return
 	operator, op_ok := parse_operator(op_token)
 	if !op_ok {
+		delete(sk_name)  // free on error
 		return
 	}
 
 	value_token := next_token(t) or_return
 	value, val_ok := resolve_attribute_value(value_token, attribute_values)
 	if !val_ok {
+		delete(sk_name)  // free on error
 		return
 	}
 
@@ -242,18 +259,21 @@ parse_sort_key_condition :: proc(
 		// IMPORTANT: after allocating `value`, do NOT use `or_return` without cleanup.
 		and_token, tok_ok := next_token(t)
 		if !tok_ok || !strings.equal_fold(and_token, "AND") {
+			delete(sk_name)  // free on error
 			attr_value_destroy(&value)
 			return
 		}
 
 		value2_token, tok2_ok := next_token(t)
 		if !tok2_ok {
+			delete(sk_name)  // free on error
 			attr_value_destroy(&value)
 			return
 		}
 
 		v2, v2_ok := resolve_attribute_value(value2_token, attribute_values)
 		if !v2_ok {
+			delete(sk_name)  // free on error
 			attr_value_destroy(&value)
 			return
 		}
@@ -287,18 +307,21 @@ parse_begins_with :: proc(
 
 	comma := next_token(t) or_return
 	if comma != "," {
+		delete(sk_name)  // free on error
 		return
 	}
 
 	value_token := next_token(t) or_return
 	value, val_ok := resolve_attribute_value(value_token, attribute_values)
 	if !val_ok {
+		delete(sk_name)  // free on error
 		return
 	}
 
 	// after allocating `value`, avoid `or_return` so we can clean up
 	rparen, tok_ok := next_token(t)
 	if !tok_ok || rparen != ")" {
+		delete(sk_name)  // free on error
 		attr_value_destroy(&value)
 		return
 	}
@@ -393,13 +416,13 @@ parse_expression_attribute_names :: proc(request_body: []byte) -> Maybe(map[stri
 parse_expression_attribute_values :: proc(request_body: []byte) -> (map[string]Attribute_Value, bool) {
 	data, parse_err := json.parse(request_body, allocator = context.temp_allocator)
 	if parse_err != nil {
-		return make(map[string]Attribute_Value), true
+		return make(map[string]Attribute_Value), false
 	}
 	defer json.destroy_value(data)
 
 	root, ok := data.(json.Object)
 	if !ok {
-		return make(map[string]Attribute_Value), true
+		return make(map[string]Attribute_Value), false
 	}
 
 	values_val, found := root["ExpressionAttributeValues"]
@@ -409,7 +432,7 @@ parse_expression_attribute_values :: proc(request_body: []byte) -> (map[string]A
 
 	values_obj, values_ok := values_val.(json.Object)
 	if !values_ok {
-		return make(map[string]Attribute_Value), true
+		return make(map[string]Attribute_Value), false
 	}
 
 	result := make(map[string]Attribute_Value)
@@ -417,7 +440,13 @@ parse_expression_attribute_values :: proc(request_body: []byte) -> (map[string]A
 	for key, val in values_obj {
 		attr, attr_ok := parse_attribute_value(val)
 		if !attr_ok {
-			continue
+			// Clean up already-parsed values before returning error
+			for k, &v in result {
+				attr_value_destroy(&v)
+				delete(k)
+			}
+			delete(result)
+			return make(map[string]Attribute_Value), false
 		}
 		result[strings.clone(key)] = attr
 	}
@@ -451,7 +480,7 @@ parse_key_condition_expression_string :: proc(request_body: []byte) -> (expr: st
 		return
 	}
 
-	expr = string(kce_str)
+	expr = strings.clone(string(kce_str))
 	ok = true
 	return
 }
@@ -459,6 +488,7 @@ parse_key_condition_expression_string :: proc(request_body: []byte) -> (expr: st
 // Convenience: parse a complete Query key condition from request body
 parse_query_key_condition :: proc(request_body: []byte) -> (kc: Key_Condition, ok: bool) {
 	expression := parse_key_condition_expression_string(request_body) or_return
+	defer delete(expression)
 
 	attr_names := parse_expression_attribute_names(request_body)
 	defer {

dynamodb/filter.odin

@@ -4,8 +4,8 @@
 package dynamodb
 
 import "core:encoding/json"
-import "core:strconv"
 import "core:strings"
+import "core:mem"
 
 // ============================================================================
 // ProjectionExpression
@@ -51,6 +51,10 @@ parse_projection_expression :: proc(
 
 		resolved, res_ok := resolve_attribute_name(trimmed, attribute_names)
 		if !res_ok {
+			// Cleanup previously cloned strings
+			for path in result {
+				delete(path)
+			}
 			delete(result)
 			return nil, false
 		}
@@ -139,6 +143,7 @@ Filter_Node :: struct {
 	right:    ^Filter_Node,
 	// For Not
 	child:    ^Filter_Node,
+	allocator: mem.Allocator, // allocator that created this node
 }
 
 filter_node_destroy :: proc(node: ^Filter_Node) {
@@ -167,6 +172,9 @@ filter_node_destroy :: proc(node: ^Filter_Node) {
 	if node.child != nil {
 		filter_node_destroy(node.child)
 	}
+
+	// Free the node itself using the allocator that created it
+	free(node, node.allocator)
 }
 
 // ============================================================================
@@ -180,7 +188,17 @@ parse_filter_expression :: proc(
 ) -> (node: ^Filter_Node, ok: bool) {
 	t := tokenizer_init(expression)
 	node, ok = parse_or_expr(&t, attribute_names, attribute_values)
-	return
+	if !ok {
+		return nil, false
+	}
+
+	// Verify all tokens were consumed (no trailing garbage)
+	if trailing := tokenizer_next(&t); trailing != nil {
+		filter_node_destroy(node)
+		return nil, false
+	}
+
+	return node, true
 }
 
 parse_or_expr :: proc(
@@ -208,7 +226,7 @@ parse_or_expr :: proc(
 				return nil, false
 			}
 
-			parent := new(Filter_Node)
+			parent := make_filter_node()
 			parent.type = .Or
 			parent.left = left
 			parent.right = right
@@ -247,7 +265,7 @@ parse_and_expr :: proc(
 				return nil, false
 			}
 
-			parent := new(Filter_Node)
+			parent := make_filter_node()
 			parent.type = .And
 			parent.left = left
 			parent.right = right
@@ -278,7 +296,7 @@ parse_not_expr :: proc(
 		if !child_ok {
 			return nil, false
 		}
-		node := new(Filter_Node)
+		node := make_filter_node()
 		node.type = .Not
 		node.child = child
 		return node, true
@@ -374,7 +392,7 @@ parse_primary_expr :: proc(
 		return nil, false
 	}
 
-	node := new(Filter_Node)
+	node := make_filter_node()
 	node.type = .Comparison
 	node.path = path
 	node.comp_op = comp_op
@@ -421,7 +439,7 @@ parse_filter_begins_with :: proc(
 		return nil, false
 	}
 
-	node := new(Filter_Node)
+	node := make_filter_node()
 	node.type = .Begins_With
 	node.path = path
 	node.value = val
@@ -467,7 +485,7 @@ parse_filter_contains :: proc(
 		return nil, false
 	}
 
-	node := new(Filter_Node)
+	node := make_filter_node()
 	node.type = .Contains
 	node.path = path
 	node.value = val
@@ -498,7 +516,7 @@ parse_filter_attr_exists :: proc(
 		return nil, false
 	}
 
-	node := new(Filter_Node)
+	node := make_filter_node()
 	node.type = .Attribute_Exists if exists else .Attribute_Not_Exists
 	node.path = path
 	return node, true
@@ -536,7 +554,7 @@ parse_filter_between :: proc(
 		return nil, false
 	}
 
-	node := new(Filter_Node)
+	node := make_filter_node()
 	node.type = .Between
 	node.path = path
 	node.value = lo_val
@@ -597,7 +615,7 @@ parse_filter_in :: proc(
 		}
 	}
 
-	node := new(Filter_Node)
+	node := make_filter_node()
 	node.type = .In
 	node.path = path
 	node.in_values = in_vals[:]
@@ -688,6 +706,12 @@ evaluate_filter :: proc(item: Item, node: ^Filter_Node) -> bool {
 evaluate_comparison :: proc(attr: Attribute_Value, op: Comparison_Op, val: Attribute_Value) -> bool {
 	cmp := compare_attribute_values(attr, val)
 
+	// -2 means types are incomparable - all comparisons return false
+	// (matches DynamoDB behavior: mixed-type comparisons always fail)
+	if cmp == -2 {
+		return false
+	}
+
 	switch op {
 	case .EQ: return cmp == 0
 	case .NE: return cmp != 0
@@ -716,10 +740,10 @@ evaluate_contains :: proc(attr: Attribute_Value, val: Attribute_Value) -> bool {
 			}
 		}
 
-	case Number_Set:
-		if v, ok := val.(Number); ok {
-			for n in a {
-				if n == string(v) {
+	case DDB_Number_Set:
+		if v, ok := val.(DDB_Number); ok {
+			for num in a {
+				if compare_ddb_numbers(num, v) == 0 {
 					return true
 				}
 			}
@@ -755,21 +779,13 @@ compare_attribute_values :: proc(a: Attribute_Value, b: Attribute_Value) -> int
 		return -2
 	}
 
-	// For Numbers, do numeric comparison
-	_, a_is_num := a.(Number)
-	_, b_is_num := b.(Number)
+	// For Numbers, do with DDB_Number comparison
+	_, a_is_num := a.(DDB_Number)
+	_, b_is_num := b.(DDB_Number)
 	if a_is_num && b_is_num {
-		a_val, a_parse := strconv.parse_f64(a_str)
-		b_val, b_parse := strconv.parse_f64(b_str)
-		if a_parse && b_parse {
-			if a_val < b_val {
-				return -1
-			}
-			if a_val > b_val {
-				return 1
-			}
-			return 0
-		}
+		a_num := a.(DDB_Number)
+		b_num := b.(DDB_Number)
+		return compare_ddb_numbers(a_num, b_num)
 	}
 
 	return strings.compare(a_str, b_str)
@@ -801,7 +817,17 @@ parse_filter_expression_string :: proc(request_body: []byte) -> (expr: string, o
 		return
 	}
 
-	expr = string(fe_str)
+	expr = strings.clone(string(fe_str))
 	ok = true
 	return
 }
+
+// ============================================================================
+// Allocator Helper
+// ============================================================================
+
+make_filter_node :: proc() -> ^Filter_Node {
+	node := new(Filter_Node)
+	node.allocator = context.allocator
+	return node
+}

dynamodb/gsi.odin

@@ -20,6 +20,9 @@
 //   delete    → for each GSI, extract GSI key attrs from the OLD item, delete GSI entry
 //   update    → delete OLD GSI entries, write NEW GSI entries
 //
+// ATOMICITY: All GSI operations use WriteBatch to ensure that GSI entries are
+//            maintained atomically with the base item write/delete.
+//
 package dynamodb
 
 import "core:slice"
@@ -39,25 +42,22 @@ GSI_Key_Values :: struct {
 }
 
 // Extract GSI key values from an item based on the GSI's key schema.
-// Returns ok=false if the required partition key attribute is missing (sparse index).
+// Returns ok=false if ANY required key attribute is missing (sparse index).
+// DynamoDB sparse index semantics: item must have ALL key attributes defined in the GSI schema.
 gsi_extract_key_values :: proc(item: Item, gsi_key_schema: []Key_Schema_Element) -> (GSI_Key_Values, bool) {
 	result: GSI_Key_Values
 
 	for ks in gsi_key_schema {
 		attr, found := item[ks.attribute_name]
 		if !found {
-			if ks.key_type == .HASH {
-				return {}, false // PK missing → sparse, skip this GSI entry
-			}
-			continue // SK missing is OK, just no SK segment
+			// Any key attribute missing → sparse index, skip this item
+			return {}, false
 		}
 
 		raw, raw_ok := attr_value_to_bytes(attr)
 		if !raw_ok {
-			if ks.key_type == .HASH {
-				return {}, false
-			}
-			continue
+			// Can't convert attribute to bytes → skip this item
+			return {}, false
 		}
 
 		switch ks.key_type {
@@ -76,8 +76,8 @@ attr_value_to_bytes :: proc(attr: Attribute_Value) -> ([]byte, bool) {
 	#partial switch v in attr {
 	case String:
 		return transmute([]byte)string(v), true
-	case Number:
-		return transmute([]byte)string(v), true
+	case DDB_Number:
+		return encode_ddb_number_for_sort(v), true
 	case Binary:
 		return transmute([]byte)string(v), true
 	}
@@ -156,16 +156,16 @@ gsi_project_item :: proc(
 }
 
 // ============================================================================
-// GSI Write Maintenance
+// GSI Write Maintenance - ATOMIC via WriteBatch
 //
-// Called after a successful data write to maintain GSI entries.
-// Uses WriteBatch for atomicity (all GSI entries for one item in one batch).
+// These procedures add GSI operations to a WriteBatch instead of performing
+// direct database writes. This ensures atomicity with the base item operation.
 // ============================================================================
 
-// Write GSI entries for an item across all GSIs defined on the table.
-// Should be called AFTER the main data key is written.
-gsi_write_entries :: proc(
-	engine: ^Storage_Engine,
+// Add GSI write operations to a WriteBatch for an item across all GSIs.
+// Called during put_item or update_item to maintain NEW GSI entries.
+gsi_batch_write_entries :: proc(
+	batch: ^rocksdb.WriteBatch,
 	table_name: string,
 	item: Item,
 	metadata: ^Table_Metadata,
@@ -175,15 +175,31 @@ gsi_write_entries :: proc(
 		return .None
 	}
 
+	base_key, base_ok := key_from_item(item, metadata.key_schema)
+	if !base_ok {
+		return .Missing_Key_Attribute
+	}
+	defer key_destroy(&base_key)
+
+	base_vals, base_vals_ok := key_get_values(&base_key)
+	if !base_vals_ok {
+		return .Invalid_Key
+	}
+
 	for &gsi in gsis {
 		// Extract GSI key from item
 		gsi_kv, kv_ok := gsi_extract_key_values(item, gsi.key_schema)
-		if !kv_ok {
-			continue // Sparse: item doesn't have GSI PK, skip
-		}
+		if !kv_ok do continue // item doesn't have GSI PK, skip
 
 		// Build GSI storage key
-		gsi_storage_key := build_gsi_key(table_name, gsi.index_name, gsi_kv.pk, gsi_kv.sk)
+		gsi_storage_key := build_gsi_key(
+			table_name,
+			gsi.index_name,
+			gsi_kv.pk,
+			gsi_kv.sk,
+			base_vals.pk,
+			base_vals.sk,
+		)
 		defer delete(gsi_storage_key)
 
 		// Build projected item
@@ -197,21 +213,18 @@ gsi_write_entries :: proc(
 		}
 		defer delete(encoded)
 
-		// Write to RocksDB
-		put_err := rocksdb.db_put(&engine.db, gsi_storage_key, encoded)
-		if put_err != .None {
-			return .RocksDB_Error
-		}
+		// Add to batch (not written yet)
+		rocksdb.batch_put(batch, gsi_storage_key, encoded)
 	}
 
 	return .None
 }
 
-// Delete GSI entries for an item across all GSIs.
-// Should be called BEFORE or AFTER the main data key is deleted.
+// Add GSI delete operations to a WriteBatch for an item across all GSIs.
+// Called during delete_item or update_item to remove OLD GSI entries.
 // Needs the OLD item to know which GSI keys to remove.
-gsi_delete_entries :: proc(
-	engine: ^Storage_Engine,
+gsi_batch_delete_entries :: proc(
+	batch: ^rocksdb.WriteBatch,
 	table_name: string,
 	old_item: Item,
 	metadata: ^Table_Metadata,
@@ -221,19 +234,35 @@ gsi_delete_entries :: proc(
 		return .None
 	}
 
-	for &gsi in gsis {
-		gsi_kv, kv_ok := gsi_extract_key_values(old_item, gsi.key_schema)
-		if !kv_ok {
-			continue // Item didn't have a GSI entry
-		}
+	base_key, base_ok := key_from_item(old_item, metadata.key_schema)
+	if !base_ok {
+		return .Missing_Key_Attribute
+	}
+	defer key_destroy(&base_key)
 
-		gsi_storage_key := build_gsi_key(table_name, gsi.index_name, gsi_kv.pk, gsi_kv.sk)
+	base_vals, base_vals_ok := key_get_values(&base_key)
+	if !base_vals_ok {
+		return .Invalid_Key
+	}
+
+	for &gsi in gsis {
+		// Extract GSI key from item
+		gsi_kv, kv_ok := gsi_extract_key_values(old_item, gsi.key_schema)
+		if !kv_ok do continue // old item doesn't have GSI PK, skip
+
+		// Build GSI storage key
+		gsi_storage_key := build_gsi_key(
+			table_name,
+			gsi.index_name,
+			gsi_kv.pk,
+			gsi_kv.sk,
+			base_vals.pk,
+			base_vals.sk,
+		)
 		defer delete(gsi_storage_key)
 
-		del_err := rocksdb.db_delete(&engine.db, gsi_storage_key)
-		if del_err != .None {
-			return .RocksDB_Error
-		}
+		// Add to batch (not written yet)
+		rocksdb.batch_delete(batch, gsi_storage_key)
 	}
 
 	return .None

dynamodb/item_codec.odin

@@ -76,10 +76,12 @@ encode_attribute_value :: proc(buf: ^bytes.Buffer, attr: Attribute_Value) -> boo
 		encode_varint(buf, len(v))
 		bytes.buffer_write_string(buf, string(v))
 
-	case Number:
+	case DDB_Number:
 		bytes.buffer_write_byte(buf, u8(Type_Tag.Number))
-		encode_varint(buf, len(v))
-		bytes.buffer_write_string(buf, string(v))
+		// Store as string in item encoding
+		num_str := format_ddb_number(v)
+		encode_varint(buf, len(num_str))
+		bytes.buffer_write_string(buf, num_str)
 
 	case Binary:
 		bytes.buffer_write_byte(buf, u8(Type_Tag.Binary))
@@ -94,6 +96,16 @@ encode_attribute_value :: proc(buf: ^bytes.Buffer, attr: Attribute_Value) -> boo
 		bytes.buffer_write_byte(buf, u8(Type_Tag.Null))
 		// NULL has no value bytes
 
+	case DDB_Number_Set:
+		bytes.buffer_write_byte(buf, u8(Type_Tag.Number_Set))  // Use Number_Set tag, not DDB_Number_Set
+		encode_varint(buf, len(v))
+		for num in v {
+			// Format the DDB_Number to a string
+			num_str := format_ddb_number(num)
+			encode_varint(buf, len(num_str))
+			bytes.buffer_write_string(buf, num_str)
+		}
+
 	case String_Set:
 		bytes.buffer_write_byte(buf, u8(Type_Tag.String_Set))
 		encode_varint(buf, len(v))
@@ -102,14 +114,6 @@ encode_attribute_value :: proc(buf: ^bytes.Buffer, attr: Attribute_Value) -> boo
 			bytes.buffer_write_string(buf, s)
 		}
 
-	case Number_Set:
-		bytes.buffer_write_byte(buf, u8(Type_Tag.Number_Set))
-		encode_varint(buf, len(v))
-		for n in v {
-			encode_varint(buf, len(n))
-			bytes.buffer_write_string(buf, n)
-		}
-
 	case Binary_Set:
 		bytes.buffer_write_byte(buf, u8(Type_Tag.Binary_Set))
 		encode_varint(buf, len(v))
@@ -289,9 +293,15 @@ decode_attribute_value :: proc(decoder: ^Binary_Decoder) -> (Attribute_Value, bo
 			return nil, false
 		}
 
-		str := string(data)
-		owned := transmute(string)slice.clone(transmute([]byte)str)
-		return Number(owned), true
+		num_str := string(data)
+
+		// Parse into DDB_Number
+		ddb_num, num_ok := parse_ddb_number(num_str)
+		if !num_ok {
+			return nil, false
+		}
+
+		return ddb_num, true
 
 	case .Binary:
 		length, len_ok := decoder_read_varint(decoder)
@@ -359,32 +369,35 @@ decode_attribute_value :: proc(decoder: ^Binary_Decoder) -> (Attribute_Value, bo
 			return nil, false
 		}
 
-		numbers := make([]string, count)
+		numbers := make([]DDB_Number, count)  // Changed to DDB_Number
 
 		for i in 0..<count {
 			length, len_ok := decoder_read_varint(decoder)
 			if !len_ok {
-				for j in 0..<i {
-					delete(numbers[j])
-				}
+				// No cleanup needed for DDB_Number (no heap allocations)
 				delete(numbers)
 				return nil, false
 			}
 
 			data, data_ok := decoder_read_bytes(decoder, length)
 			if !data_ok {
-				for j in 0..<i {
-					delete(numbers[j])
-				}
 				delete(numbers)
 				return nil, false
 			}
 
-			str := string(data)
-			numbers[i] = transmute(string)slice.clone(transmute([]byte)str)
+			num_str := string(data)
+
+			// Parse into DDB_Number
+			ddb_num, num_ok := parse_ddb_number(num_str)
+			if !num_ok {
+				delete(numbers)
+				return nil, false
+			}
+
+			numbers[i] = ddb_num
 		}
 
-		return Number_Set(numbers), true
+		return DDB_Number_Set(numbers), true
 
 	case .Binary_Set:
 		count, count_ok := decoder_read_varint(decoder)

dynamodb/json.odin

@@ -85,7 +85,16 @@ parse_attribute_value :: proc(value: json.Value) -> (Attribute_Value, bool) {
 			if !str_ok {
 				return nil, false
 			}
-			return Number(strings.clone(string(str))), true
+
+			// Parse into DDB_Number
+			ddb_num, num_ok := parse_ddb_number(string(str))
+			if !num_ok {
+				return nil, false
+			}
+
+			// Clone the string fields since they're slices of the input
+			owned_num := clone_ddb_number(ddb_num)
+			return owned_num, true
 		}
 
 		// Binary (base64 string)
@@ -147,22 +156,38 @@ parse_attribute_value :: proc(value: json.Value) -> (Attribute_Value, bool) {
 				return nil, false
 			}
 
-			numbers_arr := make([]string, len(arr))
+			numbers_arr := make([]DDB_Number, len(arr))
 
 			for item, i in arr {
 				str, str_ok := item.(json.String)
 				if !str_ok {
 					// Cleanup on error
 					for j in 0..<i {
-						delete(numbers_arr[j])
+						// Clean up DDB_Numbers
+						delete(numbers_arr[j].integer_part)
+						delete(numbers_arr[j].fractional_part)
 					}
 					delete(numbers_arr)
 					return nil, false
 				}
-				numbers_arr[i] = strings.clone(string(str))
+
+				// Parse into DDB_Number
+				ddb_num, num_ok := parse_ddb_number(string(str))
+				if !num_ok {
+					// Cleanup on error
+					for j in 0..<i {
+						delete(numbers_arr[j].integer_part)
+						delete(numbers_arr[j].fractional_part)
+					}
+					delete(numbers_arr)
+					return nil, false
+				}
+
+				// Clone and store
+				numbers_arr[i] = clone_ddb_number(ddb_num)
 			}
 
-			return Number_Set(numbers_arr), true
+			return DDB_Number_Set(numbers_arr), true
 		}
 
 		// Binary Set
@@ -297,16 +322,25 @@ serialize_item_to_builder :: proc(b: ^strings.Builder, item: Item) {
 serialize_attribute_value :: proc(b: ^strings.Builder, attr: Attribute_Value) {
 	switch v in attr {
 	case String:
-		fmt.sbprintf(b, `{"S":"%s"}`, string(v))
+		strings.write_string(b, `{"S":"`)
+		strings.write_string(b, string(v))
+		strings.write_string(b, `"}`)
 
-	case Number:
-		fmt.sbprintf(b, `{"N":"%s"}`, string(v))
+	case DDB_Number:
+		num_str := format_ddb_number(v)
+		strings.write_string(b, `{"N":"`)
+		strings.write_string(b, num_str)
+		strings.write_string(b, `"}`)
 
 	case Binary:
-		fmt.sbprintf(b, `{"B":"%s"}`, string(v))
+		strings.write_string(b, `{"B":"`)
+		strings.write_string(b, string(v))
+		strings.write_string(b, `"}`)
 
 	case Bool:
-		fmt.sbprintf(b, `{"BOOL":%v}`, bool(v))
+		strings.write_string(b, `{"BOOL":`)
+		if bool(v) { strings.write_string(b, "true") } else { strings.write_string(b, "false") }
+		strings.write_string(b, "}")
 
 	case Null:
 		strings.write_string(b, `{"NULL":true}`)
@@ -321,13 +355,14 @@ serialize_attribute_value :: proc(b: ^strings.Builder, attr: Attribute_Value) {
 		}
 		strings.write_string(b, "]}")
 
-	case Number_Set:
+	case DDB_Number_Set:
 		strings.write_string(b, `{"NS":[`)
-		for n, i in v {
+		for num, i in v {
 			if i > 0 {
 				strings.write_string(b, ",")
 			}
-			fmt.sbprintf(b, `"%s"`, n)
+			num_str := format_ddb_number(num)
+			fmt.sbprintf(b, `"%s"`, num_str)
 		}
 		strings.write_string(b, "]}")
 
@@ -404,7 +439,7 @@ parse_table_name :: proc(request_body: []byte) -> (string, bool) {
 		return "", false
 	}
 
-	return string(table_name_str), true
+	return strings.clone(string(table_name_str)), true
 }
 
 // Parse Item field from request body
@@ -494,45 +529,49 @@ parse_limit :: proc(request_body: []byte) -> int {
 // Returns nil (not an error) when the field is absent.
 // ============================================================================
 
+// Returns (key, ok, body_parse_err).
+//   ok=true,  body_parse_err=false → key present and valid, or key absent (no pagination)
+//   ok=false, body_parse_err=true  → request body is not valid JSON or not an object
+//   ok=false, body_parse_err=false → ExclusiveStartKey present but malformed/invalid
 parse_exclusive_start_key :: proc(
 	request_body: []byte,
 	table_name: string,
 	key_schema: []Key_Schema_Element,
-) -> (result: Maybe([]byte), ok: bool) {
+) -> (result: Maybe([]byte), ok: bool, body_err: bool) {
 	data, parse_err := json.parse(request_body, allocator = context.temp_allocator)
 	if parse_err != nil {
-		return nil, true // no ESK is fine
+		return nil, false, true // body is not valid JSON — real error
 	}
 	defer json.destroy_value(data)
 
 	root, root_ok := data.(json.Object)
 	if !root_ok {
-		return nil, true
+		return nil, false, true // root must be an object — real error
 	}
 
 	esk_val, found := root["ExclusiveStartKey"]
 	if !found {
-		return nil, true // absent → no pagination, that's ok
+		return nil, true, false // absent → no pagination, that's ok
 	}
 
 	// Parse ExclusiveStartKey as a DynamoDB Item
 	key_item, item_ok := parse_item_from_value(esk_val)
 	if !item_ok {
-		return nil, false // present but malformed → real error
+		return nil, false, false // present but malformed → validation error
 	}
 	defer item_destroy(&key_item)
 
 	// Validate and extract key struct using schema
 	key_struct, key_ok := key_from_item(key_item, key_schema)
 	if !key_ok {
-		return nil, false // missing required key attributes
+		return nil, false, false // missing required key attributes
 	}
 	defer key_destroy(&key_struct)
 
 	// Get raw byte values
 	key_values, kv_ok := key_get_values(&key_struct)
 	if !kv_ok {
-		return nil, false
+		return nil, false, false
 	}
 
 	// Build binary storage key
@@ -542,6 +581,53 @@ parse_exclusive_start_key :: proc(
 	return
 }
 
+// parse_exclusive_start_key_gsi ... Just a helper for GSI keys
+// Returns (key, ok, body_parse_err) — same contract as parse_exclusive_start_key.
+parse_exclusive_start_key_gsi :: proc(
+	request_body: []byte,
+	table_name: string,
+	metadata: ^Table_Metadata,
+	gsi: ^Global_Secondary_Index,
+) -> (Maybe([]byte), bool, bool) {
+	root, parse_err := json.parse(request_body)
+	if parse_err != nil do return nil, false, true // body not valid JSON
+	defer json.destroy_value(root)
+
+	obj, obj_ok := root.(json.Object)
+	if !obj_ok do return nil, false, true // root must be an object
+
+	esk_val, has := obj["ExclusiveStartKey"]
+	if !has do return nil, true, false // absent → no pagination
+
+	key_item, key_ok := parse_item_from_value(esk_val)
+	if !key_ok do return nil, false, false
+	defer item_destroy(&key_item)
+
+	idx_key, idx_ok := key_from_item(key_item, gsi.key_schema)
+	if !idx_ok do return nil, false, false
+	defer key_destroy(&idx_key)
+
+	idx_vals, idx_vals_ok := key_get_values(&idx_key)
+	if !idx_vals_ok do return nil, false, false
+
+	base_key, base_ok := key_from_item(key_item, metadata.key_schema)
+	if !base_ok do return nil, false, false
+	defer key_destroy(&base_key)
+
+	base_vals, base_vals_ok := key_get_values(&base_key)
+	if !base_vals_ok do return nil, false, false
+
+	k := build_gsi_key(
+		table_name,
+		gsi.index_name,
+		idx_vals.pk,
+		idx_vals.sk,
+		base_vals.pk,
+		base_vals.sk,
+	)
+	return k, true, false
+}
+
 // ============================================================================
 // LastEvaluatedKey Generation (Pagination Output)
 //
@@ -613,3 +699,122 @@ serialize_last_evaluated_key :: proc(
 
 	return serialize_item(item), true
 }
+
+Decoded_GSI_Key_Full :: struct {
+	gsi_pk:  []byte,
+	gsi_sk:  Maybe([]byte),
+	base_pk: []byte,
+	base_sk: Maybe([]byte),
+}
+
+// Decode binary GSI key:
+//
+//   [gsi][table_name][index_name][gsi_pk][gsi_sk?][base_pk][base_sk?]
+//
+// Presence of gsi_sk/base_sk depends on whether the index/table has a RANGE key.
+decode_gsi_key_full_borrowed :: proc(
+	binary_key: []byte,
+	gsi_has_sort_key: bool,
+	table_has_sort_key: bool,
+) -> (result: Decoded_GSI_Key_Full, ok: bool) {
+	decoder := Key_Decoder{data = binary_key, pos = 0}
+
+	et := decoder_read_entity_type(&decoder) or_return
+	if et != .GSI {
+		return {}, false
+	}
+
+	// Skip table name + index name
+	_ = decoder_read_segment_borrowed(&decoder) or_return
+	_ = decoder_read_segment_borrowed(&decoder) or_return
+
+	// Read GSI PK
+	result.gsi_pk = decoder_read_segment_borrowed(&decoder) or_return
+
+	// Read GSI SK if index has one
+	if gsi_has_sort_key {
+		sk := decoder_read_segment_borrowed(&decoder) or_return
+		result.gsi_sk = sk
+	}
+
+	// Read base PK
+	result.base_pk = decoder_read_segment_borrowed(&decoder) or_return
+
+	// Read base SK if table has one
+	if table_has_sort_key {
+		sk := decoder_read_segment_borrowed(&decoder) or_return
+		result.base_sk = sk
+	}
+
+	return result, true
+}
+
+
+// Serialize a binary *GSI* key into a DynamoDB LastEvaluatedKey JSON object.
+// The output must include the *index* key attrs + the *base table* primary key attrs,
+// so boto can round-trip ExclusiveStartKey correctly.
+serialize_last_evaluated_key_gsi :: proc(
+	binary_key: []byte,
+	metadata: ^Table_Metadata,
+	gsi: ^Global_Secondary_Index,
+) -> (result: string, ok: bool) {
+
+	// Determine whether index/table have range keys
+	_, gsi_has_sk := gsi_get_sort_key_name(gsi).?
+	_, tbl_has_sk := table_metadata_get_sort_key_name(metadata).?
+
+	decoded, dec_ok := decode_gsi_key_full_borrowed(binary_key, gsi_has_sk, tbl_has_sk)
+	if !dec_ok {
+		return "", false
+	}
+
+	// Resolve key attribute names + types
+	idx_pk_name := gsi_get_partition_key_name(gsi).? or_return
+	idx_pk_type := table_metadata_get_attribute_type(metadata, idx_pk_name).? or_return
+
+	idx_sk_name: Maybe(string) = gsi_get_sort_key_name(gsi)
+	idx_sk_type: Maybe(Scalar_Attribute_Type) = nil
+	if n, has := idx_sk_name.?; has {
+		idx_sk_type = table_metadata_get_attribute_type(metadata, n)
+	}
+
+	base_pk_name := table_metadata_get_partition_key_name(metadata).? or_return
+	base_pk_type := table_metadata_get_attribute_type(metadata, base_pk_name).? or_return
+
+	base_sk_name: Maybe(string) = table_metadata_get_sort_key_name(metadata)
+	base_sk_type: Maybe(Scalar_Attribute_Type) = nil
+	if n, has := base_sk_name.?; has {
+		base_sk_type = table_metadata_get_attribute_type(metadata, n)
+	}
+
+	// Build LEK item
+	lek := make(Item)
+	defer item_destroy(&lek)
+
+	add_attr_once :: proc(item: ^Item, name: string, raw: []byte, t: Scalar_Attribute_Type) {
+		if _, exists := item^[name]; exists {
+			return
+		}
+		item^[strings.clone(name)] = build_attribute_value_with_type(raw, t)
+	}
+
+	// Index keys
+	add_attr_once(&lek, idx_pk_name, decoded.gsi_pk, idx_pk_type)
+
+	if sk_raw, has := decoded.gsi_sk.?; has {
+		skn := idx_sk_name.? or_return
+		skt := idx_sk_type.? or_return
+		add_attr_once(&lek, skn, sk_raw, skt)
+	}
+
+	// Base table keys
+	add_attr_once(&lek, base_pk_name, decoded.base_pk, base_pk_type)
+
+	if sk_raw, has := decoded.base_sk.?; has {
+		skn := base_sk_name.? or_return
+		skt := base_sk_type.? or_return
+		add_attr_once(&lek, skn, sk_raw, skt)
+	}
+
+	return serialize_item(lek), true
+}

dynamodb/key_codec.odin

@@ -130,32 +130,43 @@ build_partition_prefix :: proc(table_name: string, pk_value: []byte) -> []byte {
 	return bytes.buffer_to_bytes(&buf)
 }
 
-// Build GSI key: [gsi][table_name][index_name][gsi_pk][gsi_sk?]
-build_gsi_key :: proc(table_name: string, index_name: string, gsi_pk: []byte, gsi_sk: Maybe([]byte)) -> []byte {
+// Build GSI key: [gsi][table_name][index_name][gsi_pk][gsi_sk?][base_pk][base_sk?]
+build_gsi_key :: proc(
+	table_name: string,
+	index_name: string,
+	gsi_pk: []byte,
+	gsi_sk: Maybe([]byte),
+	base_pk: []byte,
+	base_sk: Maybe([]byte),
+) -> []byte {
 	buf: bytes.Buffer
 	bytes.buffer_init_allocator(&buf, 0, 512, context.allocator)
 
-	// Write entity type
 	bytes.buffer_write_byte(&buf, u8(Entity_Type.GSI))
 
-	// Write table name
 	encode_varint(&buf, len(table_name))
 	bytes.buffer_write_string(&buf, table_name)
 
-	// Write index name
 	encode_varint(&buf, len(index_name))
 	bytes.buffer_write_string(&buf, index_name)
 
-	// Write GSI partition key
 	encode_varint(&buf, len(gsi_pk))
 	bytes.buffer_write(&buf, gsi_pk)
 
-	// Write GSI sort key if present
 	if sk, ok := gsi_sk.?; ok {
 		encode_varint(&buf, len(sk))
 		bytes.buffer_write(&buf, sk)
 	}
 
+	// tie-breaker: base table primary key
+	encode_varint(&buf, len(base_pk))
+	bytes.buffer_write(&buf, base_pk)
+
+	if sk, ok := base_sk.?; ok {
+		encode_varint(&buf, len(sk))
+		bytes.buffer_write(&buf, sk)
+	}
+
 	return bytes.buffer_to_bytes(&buf)
 }
 

dynamodb/number.odin

@@ -0,0 +1,796 @@
+package dynamodb
+
+import "core:fmt"
+import "core:strconv"
+import "core:strings"
+import "core:bytes"
+
+// ============================================================================
+// DynamoDB Number Type
+//
+// DynamoDB numbers are arbitrary-precision decimals with up to 38 digits of
+// precision. They can be positive, negative, or zero.
+//
+// We store numbers internally as:
+// - sign: bool (true = positive/zero, false = negative)
+// - integer_part: string (digits only, no sign)
+// - fractional_part: string (digits only, if any)
+// - exponent: i32 (for scientific notation, if needed)
+//
+// This preserves the original precision and allows proper ordering.
+// ============================================================================
+
+DDB_Number :: struct {
+	sign:            bool,   // true = positive/zero, false = negative
+	integer_part:    string, // digits only (e.g., "123")
+	fractional_part: string, // digits only (e.g., "456" for .456)
+	exponent:        i32,    // scientific notation exponent (usually 0)
+}
+
+// Parse a number string into DDB_Number
+// Supports formats: "123", "-123", "123.456", "1.23e10", "-1.23e-5"
+parse_ddb_number :: proc(s: string) -> (DDB_Number, bool) {
+	if len(s) == 0 {
+		return {}, false
+	}
+
+	num: DDB_Number
+	str := s
+
+	// Parse sign
+	if str[0] == '-' {
+		num.sign = false
+		str = str[1:]
+	} else if str[0] == '+' {
+		num.sign = true
+		str = str[1:]
+	} else {
+		num.sign = true
+	}
+
+	if len(str) == 0 {
+		return {}, false
+	}
+
+	// Find exponent if present (e or E)
+	exp_pos := -1
+	for i in 0..<len(str) {
+		if str[i] == 'e' || str[i] == 'E' {
+			exp_pos = i
+			break
+		}
+	}
+
+	// Parse mantissa
+	mantissa := str
+	if exp_pos >= 0 {
+		mantissa = str[:exp_pos]
+		exp_str := str[exp_pos+1:]
+		exp_val, exp_ok := strconv.parse_i64(exp_str)
+		if !exp_ok {
+			return {}, false
+		}
+		num.exponent = i32(exp_val)
+	}
+
+	// Find decimal point
+	dot_pos := -1
+	for i in 0..<len(mantissa) {
+		if mantissa[i] == '.' {
+			dot_pos = i
+			break
+		}
+	}
+
+	// Parse integer and fractional parts
+	if dot_pos >= 0 {
+		num.integer_part = mantissa[:dot_pos]
+		num.fractional_part = mantissa[dot_pos+1:]
+
+		// Validate fractional part
+		for c in num.fractional_part {
+			if c < '0' || c > '9' {
+				return {}, false
+			}
+		}
+	} else {
+		num.integer_part = mantissa
+	}
+
+	// Validate integer part (at least one digit, all digits)
+	if len(num.integer_part) == 0 {
+		num.integer_part = "0"
+	}
+	for c in num.integer_part {
+		if c < '0' || c > '9' {
+			return {}, false
+		}
+	}
+
+	// Normalize: remove leading zeros from integer part (except if it's just "0")
+	num = normalize_ddb_number(num)
+
+	// Check precision (DynamoDB supports up to 38 digits)
+	total_digits := len(num.integer_part) + len(num.fractional_part)
+	if total_digits > 38 {
+		return {}, false
+	}
+
+	// Special case: if the number is zero
+	if is_ddb_number_zero(num) {
+		num.sign = true
+		num.exponent = 0
+	}
+
+	return num, true
+}
+
+// Normalize a DDB_Number (remove leading zeros, trailing fractional zeros)
+normalize_ddb_number :: proc(num: DDB_Number) -> DDB_Number {
+	result := num
+
+	// Remove leading zeros from integer part
+	int_part := num.integer_part
+	for len(int_part) > 1 && int_part[0] == '0' {
+		int_part = int_part[1:]
+	}
+	result.integer_part = int_part
+
+	// Remove trailing zeros from fractional part
+	frac_part := num.fractional_part
+	for len(frac_part) > 0 && frac_part[len(frac_part)-1] == '0' {
+		frac_part = frac_part[:len(frac_part)-1]
+	}
+	result.fractional_part = frac_part
+
+	return result
+}
+
+// Check if a DDB_Number represents zero
+is_ddb_number_zero :: proc(num: DDB_Number) -> bool {
+	// Check if integer part is all zeros
+	for c in num.integer_part {
+		if c != '0' {
+			return false
+		}
+	}
+	// Check if fractional part is all zeros
+	for c in num.fractional_part {
+		if c != '0' {
+			return false
+		}
+	}
+	return true
+}
+
+// Convert DDB_Number to string representation
+ddb_number_to_string :: proc(num: DDB_Number) -> string {
+	builder := strings.builder_make()
+
+	if !num.sign {
+		strings.write_string(&builder, "-")
+	}
+
+	strings.write_string(&builder, num.integer_part)
+
+	if len(num.fractional_part) > 0 {
+		strings.write_string(&builder, ".")
+		strings.write_string(&builder, num.fractional_part)
+	}
+
+	if num.exponent != 0 {
+		fmt.sbprintf(&builder, "e%d", num.exponent)
+	}
+
+	return strings.to_string(builder)
+}
+
+// Compare two DDB_Numbers
+// Returns: -1 if a < b, 0 if a == b, 1 if a > b
+compare_ddb_numbers :: proc(a: DDB_Number, b: DDB_Number) -> int {
+	// Handle zero cases
+	a_zero := is_ddb_number_zero(a)
+	b_zero := is_ddb_number_zero(b)
+
+	if a_zero && b_zero {
+		return 0
+	}
+	if a_zero {
+		return b.sign ? -1 : 1  // 0 < positive, 0 > negative
+	}
+	if b_zero {
+		return a.sign ? 1 : -1  // positive > 0, negative < 0
+	}
+
+	// Different signs
+	if a.sign != b.sign {
+		return a.sign ? 1 : -1  // positive > negative
+	}
+
+	// Same sign - compare magnitudes
+	mag_cmp := compare_ddb_number_magnitudes(a, b)
+
+	// If negative, reverse the comparison
+	if !a.sign {
+		return -mag_cmp
+	}
+	return mag_cmp
+}
+
+// Compare magnitudes (absolute values) of two DDB_Numbers
+compare_ddb_number_magnitudes :: proc(a: DDB_Number, b: DDB_Number) -> int {
+	// Adjust for exponents first
+	a_adj := adjust_for_exponent(a)
+	b_adj := adjust_for_exponent(b)
+
+	// Compare integer parts length
+	if len(a_adj.integer_part) != len(b_adj.integer_part) {
+		return len(a_adj.integer_part) > len(b_adj.integer_part) ? 1 : -1
+	}
+
+	// Compare integer parts digit by digit
+	for i in 0..<len(a_adj.integer_part) {
+		if a_adj.integer_part[i] != b_adj.integer_part[i] {
+			return a_adj.integer_part[i] > b_adj.integer_part[i] ? 1 : -1
+		}
+	}
+
+	// Integer parts equal, compare fractional parts
+	max_frac_len := max(len(a_adj.fractional_part), len(b_adj.fractional_part))
+	for i in 0..<max_frac_len {
+		a_digit := i < len(a_adj.fractional_part) ? a_adj.fractional_part[i] : '0'
+		b_digit := i < len(b_adj.fractional_part) ? b_adj.fractional_part[i] : '0'
+
+		if a_digit != b_digit {
+			return a_digit > b_digit ? 1 : -1
+		}
+	}
+
+	return 0
+}
+
+// Adjust a number for its exponent (conceptually multiply by 10^exponent)
+adjust_for_exponent :: proc(num: DDB_Number) -> DDB_Number {
+	if num.exponent == 0 {
+		return num
+	}
+
+	result := num
+	result.exponent = 0
+
+	if num.exponent > 0 {
+		// Shift decimal point right
+		exp := int(num.exponent)
+		frac := num.fractional_part
+
+		// Move fractional digits to integer part
+		shift := min(exp, len(frac))
+		result.integer_part = strings.concatenate({num.integer_part, frac[:shift]})
+		result.fractional_part = frac[shift:]
+
+		// Add zeros if needed
+		if exp > len(frac) {
+			zeros := strings.repeat("0", exp - len(frac))
+			result.integer_part = strings.concatenate({result.integer_part, zeros})
+		}
+	} else {
+		// Shift decimal point left
+		exp := -int(num.exponent)
+		int_part := num.integer_part
+
+		// Move integer digits to fractional part
+		shift := min(exp, len(int_part))
+		result.integer_part = int_part[:len(int_part)-shift]
+		if len(result.integer_part) == 0 {
+			result.integer_part = "0"
+		}
+		result.fractional_part = strings.concatenate({
+			int_part[len(int_part)-shift:],
+			num.fractional_part,
+		})
+
+		// Add leading zeros if needed
+		if exp > len(int_part) {
+			zeros := strings.repeat("0", exp - len(int_part))
+			result.fractional_part = strings.concatenate({zeros, result.fractional_part})
+		}
+	}
+
+	return normalize_ddb_number(result)
+}
+
+// ============================================================================
+// Canonical Encoding for Sort Keys
+//
+// For numbers to sort correctly in byte-wise comparisons, we need a
+// canonical encoding that preserves numeric ordering.
+//
+// Encoding format:
+// - 1 byte: sign/magnitude marker
+//   - 0x00: negative infinity (reserved)
+//   - 0x01-0x7F: negative numbers (inverted magnitude)
+//   - 0x80: zero
+//   - 0x81-0xFE: positive numbers (magnitude)
+//   - 0xFF: positive infinity (reserved)
+// - N bytes: encoded magnitude (variable length)
+//
+// For positive numbers: we encode the magnitude directly with leading byte
+// indicating number of integer digits.
+//
+// For negative numbers: we encode the magnitude inverted (bitwise NOT) so
+// that larger negative numbers sort before smaller ones.
+// ============================================================================
+
+// Encode a DDB_Number into canonical byte form for sort keys
+encode_ddb_number_for_sort :: proc(num: DDB_Number) -> []byte {
+	buf: bytes.Buffer
+	bytes.buffer_init_allocator(&buf, 0, 64, context.allocator)
+
+	if is_ddb_number_zero(num) {
+		bytes.buffer_write_byte(&buf, 0x80)
+		return bytes.buffer_to_bytes(&buf)
+	}
+
+	// Get normalized magnitude
+	norm := normalize_ddb_number(num)
+	adj := adjust_for_exponent(norm)
+
+	// Encode magnitude bytes
+	mag_bytes := encode_magnitude(adj)
+
+	if num.sign {
+		// Positive number: 0x81 + magnitude
+		bytes.buffer_write_byte(&buf, 0x81)
+		bytes.buffer_write(&buf, mag_bytes)
+	} else {
+		// Negative number: 0x7F - inverted magnitude
+		bytes.buffer_write_byte(&buf, 0x7F)
+		// Invert all magnitude bytes
+		for b in mag_bytes {
+			bytes.buffer_write_byte(&buf, ~b)
+		}
+	}
+
+	return bytes.buffer_to_bytes(&buf)
+}
+
+// Encode the magnitude of a number (integer + fractional parts)
+encode_magnitude :: proc(num: DDB_Number) -> []byte {
+	buf: bytes.Buffer
+	bytes.buffer_init_allocator(&buf, 0, 32, context.allocator)
+
+	// Write length of integer part as varint
+	int_len := u64(len(num.integer_part))
+	encode_varint(&buf, int_len)
+
+	// Write integer digits
+	bytes.buffer_write_string(&buf, num.integer_part)
+
+	// Write fractional digits if any
+	if len(num.fractional_part) > 0 {
+		bytes.buffer_write_string(&buf, num.fractional_part)
+	}
+
+	return bytes.buffer_to_bytes(&buf)
+}
+
+// Decode a canonically encoded number back to DDB_Number
+decode_ddb_number_from_sort :: proc(data: []byte) -> (DDB_Number, bool) {
+	if len(data) == 0 {
+		return {}, false
+	}
+
+	marker := data[0]
+
+	// Zero
+	if marker == 0x80 {
+		return DDB_Number{
+			sign = true,
+			integer_part = "0",
+			fractional_part = "",
+			exponent = 0,
+		}, true
+	}
+
+	// Positive number
+	if marker == 0x81 {
+		return decode_magnitude(data[1:], true)
+	}
+
+	// Negative number (inverted bytes)
+	if marker == 0x7F {
+		// Un-invert the bytes
+		inverted := make([]byte, len(data)-1)
+		defer delete(inverted)
+		for i in 0..<len(inverted) {
+			inverted[i] = ~data[i+1]
+		}
+		return decode_magnitude(inverted, false)
+	}
+
+	return {}, false
+}
+
+// Decode magnitude bytes back to a DDB_Number
+decode_magnitude :: proc(data: []byte, positive: bool) -> (DDB_Number, bool) {
+	if len(data) == 0 {
+		return {}, false
+	}
+
+	// Read integer length
+	int_len, bytes_read := decode_varint(data)
+	if bytes_read == 0 || int_len == 0 {
+		return {}, false
+	}
+
+	offset := bytes_read
+
+	// Read integer part
+	if offset + int(int_len) > len(data) {
+		return {}, false
+	}
+	int_part := string(data[offset:offset + int(int_len)])
+	offset += int(int_len)
+
+	// Read fractional part if any
+	frac_part := ""
+	if offset < len(data) {
+		frac_part = string(data[offset:])
+	}
+
+	return DDB_Number{
+		sign = positive,
+		integer_part = int_part,
+		fractional_part = frac_part,
+		exponent = 0,
+	}, true
+}
+
+// ============================================================================
+// Decimal Arithmetic (38-digit precision, no float conversion)
+// ============================================================================
+
+MAX_DDB_PRECISION :: 38
+
+// Add two DDB_Numbers with full decimal precision.
+// Returns an owned DDB_Number.
+add_ddb_numbers :: proc(a: DDB_Number, b: DDB_Number) -> (DDB_Number, bool) {
+	if is_ddb_number_zero(a) { return clone_ddb_number(b), true }
+	if is_ddb_number_zero(b) { return clone_ddb_number(a), true }
+
+	if a.sign == b.sign {
+		// Same sign: add magnitudes, keep sign
+		result, ok := add_magnitudes(a, b)
+		if !ok { return {}, false }
+		result.sign = a.sign
+		return result, true
+	}
+
+	// Different signs: subtract smaller magnitude from larger
+	cmp := compare_ddb_number_magnitudes(a, b)
+	if cmp == 0 {
+		return DDB_Number{
+			sign            = true,
+			integer_part    = strings.clone("0"),
+			fractional_part = strings.clone(""),
+			exponent        = 0,
+		}, true
+	}
+
+	if cmp > 0 {
+		result, ok := subtract_magnitudes(a, b)
+		if !ok { return {}, false }
+		result.sign = a.sign
+		return result, true
+	} else {
+		result, ok := subtract_magnitudes(b, a)
+		if !ok { return {}, false }
+		result.sign = b.sign
+		return result, true
+	}
+}
+
+// Subtract two DDB_Numbers: a - b
+subtract_ddb_numbers :: proc(a: DDB_Number, b: DDB_Number) -> (DDB_Number, bool) {
+	neg_b := b
+	neg_b.sign = !b.sign
+	return add_ddb_numbers(a, neg_b)
+}
+
+// ============================================================================
+// Internal arithmetic helpers
+// ============================================================================
+
+// Expand a DDB_Number to effective integer and fractional digit bytes
+// with the exponent fully applied. Returns heap-allocated slices (caller frees).
+@(private="file")
+expand_digits :: proc(num: DDB_Number) -> (int_digits: []u8, frac_digits: []u8) {
+	dp := len(num.integer_part) + int(num.exponent)
+	all_len := len(num.integer_part) + len(num.fractional_part)
+
+	if dp <= 0 {
+		// Everything is fractional, need leading zeros
+		frac := make([]u8, -dp + all_len)
+		for i in 0..<(-dp) {
+			frac[i] = '0'
+		}
+		for i in 0..<len(num.integer_part) {
+			frac[-dp + i] = num.integer_part[i]
+		}
+		for i in 0..<len(num.fractional_part) {
+			frac[-dp + len(num.integer_part) + i] = num.fractional_part[i]
+		}
+
+		int_d := make([]u8, 1)
+		int_d[0] = '0'
+		return int_d, frac
+	}
+
+	if dp >= all_len {
+		// Everything is integer, may need trailing zeros
+		int_d := make([]u8, dp)
+		for i in 0..<len(num.integer_part) {
+			int_d[i] = num.integer_part[i]
+		}
+		for i in 0..<len(num.fractional_part) {
+			int_d[len(num.integer_part) + i] = num.fractional_part[i]
+		}
+		for i in all_len..<dp {
+			int_d[i] = '0'
+		}
+		return int_d, nil
+	}
+
+	// Decimal point falls within the original integer_part
+	if dp <= len(num.integer_part) {
+		int_d := make([]u8, dp)
+		for i in 0..<dp {
+			int_d[i] = num.integer_part[i]
+		}
+
+		frac_len := (len(num.integer_part) - dp) + len(num.fractional_part)
+		frac := make([]u8, frac_len)
+		for i in dp..<len(num.integer_part) {
+			frac[i - dp] = num.integer_part[i]
+		}
+		offset := len(num.integer_part) - dp
+		for i in 0..<len(num.fractional_part) {
+			frac[offset + i] = num.fractional_part[i]
+		}
+		return int_d, frac
+	}
+
+	// Decimal point falls within the original fractional_part
+	frac_split := dp - len(num.integer_part)
+
+	int_d := make([]u8, dp)
+	for i in 0..<len(num.integer_part) {
+		int_d[i] = num.integer_part[i]
+	}
+	for i in 0..<frac_split {
+		int_d[len(num.integer_part) + i] = num.fractional_part[i]
+	}
+
+	remaining := len(num.fractional_part) - frac_split
+	frac: []u8 = nil
+	if remaining > 0 {
+		frac = make([]u8, remaining)
+		for i in frac_split..<len(num.fractional_part) {
+			frac[i - frac_split] = num.fractional_part[i]
+		}
+	}
+	return int_d, frac
+}
+
+// Normalize a DDB_Number that owns its strings.
+// Clones the trimmed result, frees the originals.
+@(private="file")
+normalize_owned :: proc(num: DDB_Number) -> DDB_Number {
+	norm := normalize_ddb_number(num)
+
+	// Clone the normalized subslices BEFORE freeing originals
+	new_int := strings.clone(norm.integer_part)
+	new_frac := strings.clone(norm.fractional_part)
+
+	// Free the originals
+	delete(num.integer_part)
+	delete(num.fractional_part)
+
+	return DDB_Number{
+		sign            = norm.sign,
+		integer_part    = new_int,
+		fractional_part = new_frac,
+		exponent        = norm.exponent,
+	}
+}
+
+// Add absolute values. Returns owned DDB_Number (sign=true).
+@(private="file")
+add_magnitudes :: proc(a: DDB_Number, b: DDB_Number) -> (DDB_Number, bool) {
+	a_int, a_frac := expand_digits(a)
+	b_int, b_frac := expand_digits(b)
+	defer { delete(a_int); delete(a_frac); delete(b_int); delete(b_frac) }
+
+	max_int  := max(len(a_int), len(b_int))
+	max_frac := max(len(a_frac), len(b_frac))
+	total    := max_int + max_frac
+
+	// Build zero-padded aligned arrays
+	a_aligned := make([]u8, total)
+	b_aligned := make([]u8, total)
+	defer { delete(a_aligned); delete(b_aligned) }
+
+	for i in 0..<total { a_aligned[i] = '0'; b_aligned[i] = '0' }
+
+	// Integer digits: right-aligned in [0..max_int)
+	a_off := max_int - len(a_int)
+	b_off := max_int - len(b_int)
+	for i in 0..<len(a_int) { a_aligned[a_off + i] = a_int[i] }
+	for i in 0..<len(b_int) { b_aligned[b_off + i] = b_int[i] }
+
+	// Fractional digits: left-aligned in [max_int..total)
+	for i in 0..<len(a_frac) { a_aligned[max_int + i] = a_frac[i] }
+	for i in 0..<len(b_frac) { b_aligned[max_int + i] = b_frac[i] }
+
+	// Add right-to-left
+	result := make([]u8, total + 1) // +1 for carry
+	carry: u8 = 0
+	for i := total - 1; i >= 0; i -= 1 {
+		sum := (a_aligned[i] - '0') + (b_aligned[i] - '0') + carry
+		result[i + 1] = (sum % 10) + '0'
+		carry = sum / 10
+	}
+	result[0] = carry + '0'
+
+	// Split: decimal point is at max_int + 1 (carry slot shifts everything)
+	int_end := max_int + 1
+	int_str  := strings.clone(string(result[:int_end]))
+	frac_str := strings.clone(string(result[int_end:]))
+	delete(result)
+
+	num := normalize_owned(DDB_Number{
+		sign            = true,
+		integer_part    = int_str,
+		fractional_part = frac_str,
+		exponent        = 0,
+	})
+
+	if len(num.integer_part) + len(num.fractional_part) > MAX_DDB_PRECISION {
+		delete(num.integer_part)
+		delete(num.fractional_part)
+		return {}, false
+	}
+
+	return num, true
+}
+
+// Subtract absolute values: |a| - |b|, where |a| >= |b|.
+// Returns owned DDB_Number (sign=true).
+@(private="file")
+subtract_magnitudes :: proc(a: DDB_Number, b: DDB_Number) -> (DDB_Number, bool) {
+	a_int, a_frac := expand_digits(a)
+	b_int, b_frac := expand_digits(b)
+	defer { delete(a_int); delete(a_frac); delete(b_int); delete(b_frac) }
+
+	max_int  := max(len(a_int), len(b_int))
+	max_frac := max(len(a_frac), len(b_frac))
+	total    := max_int + max_frac
+
+	a_aligned := make([]u8, total)
+	b_aligned := make([]u8, total)
+	defer { delete(a_aligned); delete(b_aligned) }
+
+	for i in 0..<total { a_aligned[i] = '0'; b_aligned[i] = '0' }
+
+	a_off := max_int - len(a_int)
+	b_off := max_int - len(b_int)
+	for i in 0..<len(a_int) { a_aligned[a_off + i] = a_int[i] }
+	for i in 0..<len(b_int) { b_aligned[b_off + i] = b_int[i] }
+	for i in 0..<len(a_frac) { a_aligned[max_int + i] = a_frac[i] }
+	for i in 0..<len(b_frac) { b_aligned[max_int + i] = b_frac[i] }
+
+	// Subtract right-to-left
+	result := make([]u8, total)
+	borrow: u8 = 0
+	for i := total - 1; i >= 0; i -= 1 {
+		ad := a_aligned[i] - '0'
+		bd := (b_aligned[i] - '0') + borrow
+		if ad < bd {
+			ad += 10
+			borrow = 1
+		} else {
+			borrow = 0
+		}
+		result[i] = (ad - bd) + '0'
+	}
+
+	int_str  := strings.clone(string(result[:max_int]))
+	frac_str := strings.clone(string(result[max_int:]))
+	delete(result)
+
+	if len(int_str) == 0 {
+		delete(int_str)
+		int_str = strings.clone("0")
+	}
+
+	num := normalize_owned(DDB_Number{
+		sign            = true,
+		integer_part    = int_str,
+		fractional_part = frac_str,
+		exponent        = 0,
+	})
+
+	if len(num.integer_part) + len(num.fractional_part) > MAX_DDB_PRECISION {
+		delete(num.integer_part)
+		delete(num.fractional_part)
+		return {}, false
+	}
+
+	return num, true
+}
+
+// Format a DDB_Number for display
+format_ddb_number :: proc(num: DDB_Number) -> string {
+	// Normalize first
+	norm := normalize_ddb_number(num)
+
+	// Check if it's effectively an integer
+	if len(norm.fractional_part) == 0 && norm.exponent >= 0 {
+		builder := strings.builder_make()
+		if !norm.sign {
+			strings.write_string(&builder, "-")
+		}
+		strings.write_string(&builder, norm.integer_part)
+		// Add trailing zeros for positive exponent
+		for _ in 0..<norm.exponent {
+			strings.write_string(&builder, "0")
+		}
+		return strings.to_string(builder)
+	}
+
+	// Otherwise use full representation
+	return ddb_number_to_string(norm)
+}
+
+// Clones a ddb number type
+clone_ddb_number :: proc(num: DDB_Number) -> DDB_Number {
+	return DDB_Number{
+		sign = num.sign,
+		integer_part = strings.clone(num.integer_part),
+		fractional_part = strings.clone(num.fractional_part),
+		exponent = num.exponent,
+	}
+}
+
+// Helper: encode_varint (you already have this in your codebase)
+@(private="file")
+encode_varint :: proc(buf: ^bytes.Buffer, value: u64) {
+	v := value
+	for {
+		byte_val := u8(v & 0x7F)
+		v >>= 7
+		if v != 0 {
+			byte_val |= 0x80
+		}
+		bytes.buffer_write_byte(buf, byte_val)
+		if v == 0 {
+			break
+		}
+	}
+}
+
+// Helper: decode_varint
+@(private="file")
+decode_varint :: proc(data: []byte) -> (value: u64, bytes_read: int) {
+	shift: u64 = 0
+	for i in 0..<len(data) {
+		byte_val := data[i]
+		value |= u64(byte_val & 0x7F) << shift
+		bytes_read = i + 1
+		if (byte_val & 0x80) == 0 {
+			return
+		}
+		shift += 7
+	}
+	return 0, 0
+}

dynamodb/storage.odin

@@ -22,6 +22,9 @@ Storage_Error :: enum {
 	Serialization_Error,
 	RocksDB_Error,
 	Out_Of_Memory,
+	Validation_Error,
+	Request_Too_Large,
+	Internal_Error,
 }
 
 // Result type for Scan operations with pagination
@@ -190,10 +193,14 @@ remove_table_lock :: proc(engine: ^Storage_Engine, table_name: string) {
 	sync.mutex_lock(&engine.table_locks_mutex)
 	defer sync.mutex_unlock(&engine.table_locks_mutex)
 
-	if lock, found := engine.table_locks[table_name]; found {
-		delete(table_name, engine.allocator)
-		free(lock, engine.allocator)
-		delete_key(&engine.table_locks, table_name)
+	// Find the actual heap-allocated key string from the map
+	for key, lock in engine.table_locks {
+		if key == table_name {
+			delete_key(&engine.table_locks, key)
+			delete(key, engine.allocator) // free the map's owned key!
+			free(lock, engine.allocator)
+			break
+		}
 	}
 }
 
@@ -240,7 +247,13 @@ serialize_table_metadata :: proc(metadata: ^Table_Metadata) -> ([]byte, bool) {
 
 	// Add other metadata
 	meta_item["TableStatus"] = String(strings.clone(table_status_to_string(metadata.table_status)))
-	meta_item["CreationDateTime"] = Number(fmt.aprint(metadata.creation_date_time))
+	ts_str := fmt.aprint(metadata.creation_date_time)
+	ts_num, ts_ok := parse_ddb_number(ts_str)
+	if ts_ok {
+		meta_item["CreationDateTime"] = ts_num
+	} else {
+		meta_item["CreationDateTime"] = String(strings.clone(ts_str))
+	}
 
 	// Encode GSI definitions as JSON string
 	if gsis, has_gsis := metadata.global_secondary_indexes.?; has_gsis && len(gsis) > 0 {
@@ -260,7 +273,7 @@ serialize_table_metadata :: proc(metadata: ^Table_Metadata) -> ([]byte, bool) {
 				fmt.sbprintf(&gsi_builder, `{{"AttributeName":"%s","KeyType":"%s"}}`,
 					ks.attribute_name, key_type_to_string(ks.key_type))
 			}
-			strings.write_string(&gsi_builder, `],"Projection":{{"ProjectionType":"`)
+			strings.write_string(&gsi_builder, `],"Projection":{"ProjectionType":"`)
 			switch gsi.projection.projection_type {
 			case .ALL:       strings.write_string(&gsi_builder, "ALL")
 			case .KEYS_ONLY: strings.write_string(&gsi_builder, "KEYS_ONLY")
@@ -311,8 +324,9 @@ deserialize_table_metadata :: proc(data: []byte, allocator: mem.Allocator) -> (T
 	// Parse creation date time
 	if time_val, found := meta_item["CreationDateTime"]; found {
 		#partial switch v in time_val {
-		case Number:
-			val, parse_ok := strconv.parse_i64(string(v))
+		case DDB_Number:
+			num_str := format_ddb_number(v)
+			val, parse_ok := strconv.parse_i64(num_str)
 			metadata.creation_date_time = val if parse_ok else 0
 		}
 	}
@@ -518,6 +532,10 @@ get_table_metadata :: proc(engine: ^Storage_Engine, table_name: string) -> (Tabl
 		return {}, .Serialization_Error
 	}
 
+	// table_name is not stored in the serialized blob (it IS the RocksDB key),
+	// so we populate it here from the argument we already have.
+	metadata.table_name = strings.clone(table_name, engine.allocator)
+
 	return metadata, .None
 }
 
@@ -729,6 +747,7 @@ delete_table :: proc(engine: ^Storage_Engine, table_name: string) -> Storage_Err
 // ============================================================================
 
 // Put item — uses EXCLUSIVE lock (write operation)
+// ATOMICITY: Uses WriteBatch to ensure base item + all GSI updates are atomic
 put_item :: proc(engine: ^Storage_Engine, table_name: string, item: Item) -> Storage_Error {
 	table_lock := get_or_create_table_lock(engine, table_name)
 	sync.rw_mutex_lock(table_lock)
@@ -771,34 +790,67 @@ put_item :: proc(engine: ^Storage_Engine, table_name: string, item: Item) -> Sto
 	storage_key := build_data_key(table_name, key_values.pk, key_values.sk)
 	defer delete(storage_key)
 
-	// --- GSI cleanup: delete OLD GSI entries if item already exists ---
+	// --- Check if item already exists (need old item for GSI cleanup) ---
+	old_item: Maybe(Item) = nil
 	existing_value, existing_err := rocksdb.db_get(&engine.db, storage_key)
-	if existing_err == .None && existing_value != nil {
+	if existing_err == .NotFound {
+		// Item does not exist — nothing to clean up, proceed normally.
+	} else if existing_err != .None {
+		// Unexpected RocksDB I/O error — fail closed to avoid orphaned GSI entries.
+		return .RocksDB_Error
+	} else if existing_value != nil {
 		defer delete(existing_value)
-		old_item, decode_ok := decode(existing_value)
-		if decode_ok {
-			defer item_destroy(&old_item)
-			gsi_delete_entries(engine, table_name, old_item, &metadata)
+		decoded_old, decode_ok := decode(existing_value)
+		if !decode_ok {
+			// Value exists but is unreadable — fail closed rather than leaving
+			// stale GSI entries behind after the overwrite.
+			return .Serialization_Error
+		}
+		old_item = decoded_old
+	}
+	// Cleanup old_item at the end
+	defer {
+		if old, has_old := old_item.?; has_old {
+			old_copy := old
+			item_destroy(&old_copy)
 		}
 	}
 
-	// Encode item
+	// Encode new item
 	encoded_item, encode_ok := encode(item)
 	if !encode_ok {
 		return .Serialization_Error
 	}
 	defer delete(encoded_item)
 
-	// Store in RocksDB
-	put_err := rocksdb.db_put(&engine.db, storage_key, encoded_item)
-	if put_err != .None {
+	// --- ATOMIC WRITE BATCH: base item + all GSI updates ---
+	batch, batch_err := rocksdb.batch_create()
+	if batch_err != .None {
 		return .RocksDB_Error
 	}
+	defer rocksdb.batch_destroy(&batch)
 
-	// --- GSI maintenance: write NEW GSI entries ---
-	gsi_err := gsi_write_entries(engine, table_name, item, &metadata)
-	if gsi_err != .None {
-		return gsi_err
+	// Add base item write to batch
+	rocksdb.batch_put(&batch, storage_key, encoded_item)
+
+	// Add old GSI entry deletions to batch (if item existed)
+	if old, has_old := old_item.?; has_old {
+		gsi_del_err := gsi_batch_delete_entries(&batch, table_name, old, &metadata)
+		if gsi_del_err != .None {
+			return gsi_del_err
+		}
+	}
+
+	// Add new GSI entry writes to batch
+	gsi_write_err := gsi_batch_write_entries(&batch, table_name, item, &metadata)
+	if gsi_write_err != .None {
+		return gsi_write_err
+	}
+
+	// Write batch atomically - ALL or NOTHING
+	write_err := rocksdb.batch_write(&engine.db, &batch)
+	if write_err != .None {
+		return .RocksDB_Error
 	}
 
 	return .None
@@ -861,6 +913,7 @@ get_item :: proc(engine: ^Storage_Engine, table_name: string, key: Item) -> (May
 }
 
 // Delete item — uses EXCLUSIVE lock (write operation)
+// ATOMICITY: Uses WriteBatch to ensure base item + all GSI deletions are atomic
 delete_item :: proc(engine: ^Storage_Engine, table_name: string, key: Item) -> Storage_Error {
 	table_lock := get_or_create_table_lock(engine, table_name)
 	sync.rw_mutex_lock(table_lock)
@@ -897,20 +950,59 @@ delete_item :: proc(engine: ^Storage_Engine, table_name: string, key: Item) -> S
 	storage_key := build_data_key(table_name, key_values.pk, key_values.sk)
 	defer delete(storage_key)
 
-	// --- GSI cleanup: read existing item to know which GSI entries to remove ---
+	// --- Read existing item to know which GSI entries to remove ---
+	old_item: Maybe(Item) = nil
 	existing_value, existing_err := rocksdb.db_get(&engine.db, storage_key)
-	if existing_err == .None && existing_value != nil {
+	if existing_err == .NotFound {
+		// Item does not exist — nothing to delete (DynamoDB idempotent delete).
+		return .None
+	} else if existing_err != .None {
+		// Unexpected RocksDB I/O error — fail closed.
+		return .RocksDB_Error
+	} else if existing_value != nil {
 		defer delete(existing_value)
-		old_item, decode_ok := decode(existing_value)
-		if decode_ok {
-			defer item_destroy(&old_item)
-			gsi_delete_entries(engine, table_name, old_item, &metadata)
+		decoded_old, decode_ok := decode(existing_value)
+		if !decode_ok {
+			// Value exists but is corrupt — fail closed rather than deleting the
+			// base item while leaving its GSI entries dangling.
+			return .Serialization_Error
+		}
+		old_item = decoded_old
+	}
+	// Cleanup old_item at the end
+	defer {
+		if old, has_old := old_item.?; has_old {
+			old_copy := old
+			item_destroy(&old_copy)
 		}
 	}
 
-	// Delete from RocksDB
-	del_err := rocksdb.db_delete(&engine.db, storage_key)
-	if del_err != .None {
+	// If item doesn't exist (existing_value was nil with no error), nothing to delete.
+	if _, has_old := old_item.?; !has_old {
+		return .None
+	}
+
+	// --- ATOMIC WRITE BATCH: base item deletion + all GSI deletions ---
+	batch, batch_err := rocksdb.batch_create()
+	if batch_err != .None {
+		return .RocksDB_Error
+	}
+	defer rocksdb.batch_destroy(&batch)
+
+	// Add base item delete to batch
+	rocksdb.batch_delete(&batch, storage_key)
+
+	// Add GSI entry deletions to batch
+	if old, has_old := old_item.?; has_old {
+		gsi_del_err := gsi_batch_delete_entries(&batch, table_name, old, &metadata)
+		if gsi_del_err != .None {
+			return gsi_del_err
+		}
+	}
+
+	// Write batch atomically - ALL or NOTHING
+	write_err := rocksdb.batch_write(&engine.db, &batch)
+	if write_err != .None {
 		return .RocksDB_Error
 	}
 
@@ -1166,6 +1258,43 @@ evaluate_sort_key_condition :: proc(item: Item, skc: ^Sort_Key_Condition) -> boo
 		return false
 	}
 
+	// Use numeric comparison if both sides are DDB_Number
+	item_num, item_is_num := attr.(DDB_Number)
+	cond_num, cond_is_num := skc.value.(DDB_Number)
+
+	if item_is_num && cond_is_num {
+		cmp := compare_ddb_numbers(item_num, cond_num)
+
+		switch skc.operator {
+		case .EQ:
+			return cmp == 0
+		case .LT:
+			return cmp < 0
+		case .LE:
+			return cmp <= 0
+		case .GT:
+			return cmp > 0
+		case .GE:
+			return cmp >= 0
+		case .BETWEEN:
+			if v2, has_v2 := skc.value2.?; has_v2 {
+				upper_num, upper_ok := v2.(DDB_Number)
+				if !upper_ok {
+					return false
+				}
+				cmp2 := compare_ddb_numbers(item_num, upper_num)
+				return cmp >= 0 && cmp2 <= 0
+			}
+			return false
+		case .BEGINS_WITH:
+			// begins_with is not a valid operator for Number sort keys.
+			// DynamoDB rejects this at validation time. Return false.
+			return false
+		}
+		return false
+	}
+
+	// Fallback: string comparison for S/B types
 	item_sk_str, ok1 := attr_value_to_string_for_compare(attr)
 	if !ok1 {
 		return false
@@ -1212,8 +1341,10 @@ attr_value_to_string_for_compare :: proc(attr: Attribute_Value) -> (string, bool
 	#partial switch v in attr {
 	case String:
 		return string(v), true
-	case Number:
-		return string(v), true
+	case DDB_Number:
+		// Return formatted string for fallback string comparison
+		// (actual numeric comparison is handled in compare_attribute_values)
+		return format_ddb_number(v), true
 	case Binary:
 		return string(v), true
 	}
@@ -1258,7 +1389,7 @@ validate_item_key_types :: proc(
 		#partial switch _ in attr {
 		case String:
 			match = (et == .S)
-		case Number:
+		case DDB_Number:
 			match = (et == .N)
 		case Binary:
 			match = (et == .B)

dynamodb/transact.odin

@@ -54,6 +54,10 @@ Cancellation_Reason :: struct {
 }
 
 transact_write_action_destroy :: proc(action: ^Transact_Write_Action) {
+	delete(action.table_name)
+	if ce, has := action.condition_expr.?; has {
+		delete(ce)
+	}
 	if item, has := action.item.?; has {
 		item_copy := item
 		item_destroy(&item_copy)
@@ -124,13 +128,11 @@ transact_write_items :: proc(
 		table_set[action.table_name] = true
 	}
 
-	// Acquire exclusive locks on all tables in deterministic order
-	// to prevent deadlocks
 	table_names := make([dynamic]string, allocator = context.temp_allocator)
 	for name in table_set {
 		append(&table_names, name)
 	}
-	// Simple sort for deterministic lock ordering
+	// Sort for deterministic lock ordering
 	for i := 0; i < len(table_names); i += 1 {
 		for j := i + 1; j < len(table_names); j += 1 {
 			if table_names[j] < table_names[i] {
@@ -146,17 +148,15 @@ transact_write_items :: proc(
 		append(&locks, lock)
 	}
 	defer {
-		// Release all locks in reverse order
 		for i := len(locks) - 1; i >= 0; i -= 1 {
 			sync.rw_mutex_unlock(locks[i])
 		}
 	}
 
-	// ---- Step 2: Pre-flight — fetch metadata and existing items, evaluate conditions ----
+	// ---- Step 2: Fetch metadata and evaluate conditions ----
 	reasons := make([]Cancellation_Reason, len(actions))
 	any_failed := false
 
-	// Cache table metadata to avoid redundant lookups
 	metadata_cache := make(map[string]Table_Metadata, allocator = context.temp_allocator)
 	defer {
 		for _, meta in metadata_cache {
@@ -166,7 +166,6 @@ transact_write_items :: proc(
 	}
 
 	for action, idx in actions {
-		// Get table metadata (cached)
 		metadata: ^Table_Metadata
 		if cached, found := &metadata_cache[action.table_name]; found {
 			metadata = cached
@@ -184,12 +183,11 @@ transact_write_items :: proc(
 			metadata = &metadata_cache[action.table_name]
 		}
 
-		// Determine the key item for this action
 		key_item: Item
 		switch action.type {
 		case .Put:
 			if item, has := action.item.?; has {
-				key_item = item // For Put, key is extracted from the item
+				key_item = item
 			} else {
 				reasons[idx] = Cancellation_Reason{
 					code    = "ValidationError",
@@ -211,9 +209,8 @@ transact_write_items :: proc(
 			}
 		}
 
-		// Evaluate ConditionExpression if present
+		// Evaluate ConditionExpression
 		if cond_str, has_cond := action.condition_expr.?; has_cond {
-			// Fetch existing item
 			existing_item, get_err := get_item_internal(engine, action.table_name, key_item, metadata)
 			if get_err != .None && get_err != .Item_Not_Found {
 				reasons[idx] = Cancellation_Reason{
@@ -230,7 +227,6 @@ transact_write_items :: proc(
 				}
 			}
 
-			// Parse and evaluate condition
 			filter_node, parse_ok := parse_filter_expression(
 				cond_str, action.expr_attr_names, action.expr_attr_values,
 			)
@@ -263,13 +259,12 @@ transact_write_items :: proc(
 			}
 		}
 
-		// ConditionCheck actions only validate — they don't mutate
 		if action.type == .Condition_Check {
 			reasons[idx] = Cancellation_Reason{code = "None"}
 			continue
 		}
 
-		// Validate key/item against schema
+		// Validate key/item
 		switch action.type {
 		case .Put:
 			if item, has := action.item.?; has {
@@ -286,58 +281,136 @@ transact_write_items :: proc(
 				}
 			}
 		case .Delete, .Update:
-			// Key validation happens during execution
+			// Key validation happens during batch building
 		case .Condition_Check:
-			// Already handled above
+			// Already handled
 		}
 
 		reasons[idx] = Cancellation_Reason{code = "None"}
 	}
 
-	// ---- Step 3: If any condition failed, return cancellation ----
 	if any_failed {
 		result.cancellation_reasons = reasons
 		return result, .Cancelled
 	}
 
-	// ---- Step 4: Apply all mutations ----
-	for &action, idx in actions {
+	// ---- Step 3: Build atomic WriteBatch with all operations ----
+	batch, batch_err := rocksdb.batch_create()
+	if batch_err != .None {
+		result.cancellation_reasons = reasons
+		return result, .Internal_Error
+	}
+	defer rocksdb.batch_destroy(&batch)
+
+	// Read old items for GSI cleanup (must happen before batch write)
+	old_items := make([]Maybe(Item), len(actions), allocator = context.temp_allocator)
+	defer {
+		for old_item in old_items {
+			if old, has := old_item.?; has {
+				old_copy := old
+				item_destroy(&old_copy)
+			}
+		}
+	}
+
+	for action, idx in actions {
+		if action.type == .Condition_Check {
+			continue
+		}
+
 		metadata := &metadata_cache[action.table_name]
 
-		apply_err := transact_apply_action(engine, &action, metadata)
+		// Read old item if needed for GSI cleanup
+		key_item: Item
+		#partial switch action.type {
+		case .Put:
+			if item, has := action.item.?; has {
+				key_item = item
+			}
+		case .Delete, .Update:
+			if key, has := action.key.?; has {
+				key_item = key
+			}
+		}
+
+		existing, read_err := get_item_internal(engine, action.table_name, key_item, metadata)
+		#partial switch read_err {
+			case .None:
+				// Item found or not found — both fine.
+			case .RocksDB_Error, .Serialization_Error, .Internal_Error:
+				// Cannot safely determine old index keys — cancel the entire transaction.
+				reasons[idx] = Cancellation_Reason{
+					code    = "InternalError",
+					message = "Failed to read existing item for index maintenance",
+				}
+				result.cancellation_reasons = reasons
+				return result, .Internal_Error
+			case .Missing_Key_Attribute, .Invalid_Key:
+				// The key we built from the action's own item/key should always be valid
+				// by this point (validated earlier), but treat defensively.
+				reasons[idx] = Cancellation_Reason{
+					code    = "ValidationError",
+					message = "Invalid key when reading existing item",
+				}
+				result.cancellation_reasons = reasons
+				return result, .Internal_Error
+			case .Table_Not_Found, .Item_Not_Found, .Validation_Error:
+				// These should not be returned by get_item_internal, but handle
+				// defensively — treat as "item does not exist" and continue.
+		}
+		old_items[idx] = existing
+	}
+
+	// Add all operations to batch
+	for &action, idx in actions {
+		if action.type == .Condition_Check {
+			continue
+		}
+
+		metadata := &metadata_cache[action.table_name]
+		old_item := old_items[idx]
+
+		apply_err := transact_apply_action_batch(&batch, engine, &action, metadata, old_item)
 		if apply_err != .None {
-			// This shouldn't happen after pre-validation, but handle gracefully
 			reasons[idx] = Cancellation_Reason{
 				code    = "InternalError",
-				message = "Failed to apply mutation",
+				message = "Failed to build mutation",
 			}
-			// In a real impl we'd need to rollback. For now, report the failure.
 			result.cancellation_reasons = reasons
 			return result, .Internal_Error
 		}
 	}
 
+	// ---- Step 4: Write batch atomically (ALL or NOTHING) ----
+	write_err := rocksdb.batch_write(&engine.db, &batch)
+	if write_err != .None {
+		result.cancellation_reasons = reasons
+		return result, .Internal_Error
+	}
+
 	delete(reasons)
 	return result, .None
 }
 
 // Apply a single transact write action (called after all conditions have passed)
 @(private = "file")
-transact_apply_action :: proc(
+transact_apply_action_batch :: proc(
+	batch: ^rocksdb.WriteBatch,
 	engine: ^Storage_Engine,
 	action: ^Transact_Write_Action,
 	metadata: ^Table_Metadata,
+	old_item: Maybe(Item),
 ) -> Storage_Error {
 	switch action.type {
 	case .Put:
 		if item, has := action.item.?; has {
-			return put_item_internal(engine, action.table_name, item, metadata)
+			return put_item_batch(batch, engine, action.table_name, item, metadata, old_item)
 		}
 		return .Invalid_Key
 
 	case .Delete:
 		if key, has := action.key.?; has {
-			return delete_item_internal(engine, action.table_name, key, metadata)
+			return delete_item_batch(batch, engine, action.table_name, key, metadata, old_item)
 		}
 		return .Invalid_Key
 
@@ -345,19 +418,177 @@ transact_apply_action :: proc(
 		if key, has := action.key.?; has {
 			if plan, has_plan := action.update_plan.?; has_plan {
 				plan_copy := plan
-				_, _, err := update_item_internal(engine, action.table_name, key, &plan_copy, metadata)
-				return err
+				return update_item_batch(batch, engine, action.table_name, key, &plan_copy, metadata, old_item)
 			}
 			return .Invalid_Key
 		}
 		return .Invalid_Key
 
 	case .Condition_Check:
-		return .None // No mutation
+		return .None
 	}
 	return .None
 }
 
+@(private = "file")
+put_item_batch :: proc(
+	batch: ^rocksdb.WriteBatch,
+	engine: ^Storage_Engine,
+	table_name: string,
+	item: Item,
+	metadata: ^Table_Metadata,
+	old_item: Maybe(Item),
+) -> Storage_Error {
+	key_struct, key_ok := key_from_item(item, metadata.key_schema)
+	if !key_ok {
+		return .Missing_Key_Attribute
+	}
+	defer key_destroy(&key_struct)
+
+	key_values, kv_ok := key_get_values(&key_struct)
+	if !kv_ok {
+		return .Invalid_Key
+	}
+
+	storage_key := build_data_key(table_name, key_values.pk, key_values.sk)
+	defer delete(storage_key)
+
+	encoded_item, encode_ok := encode(item)
+	if !encode_ok {
+		return .Serialization_Error
+	}
+	defer delete(encoded_item)
+
+	// Add base item to batch
+	rocksdb.batch_put(batch, storage_key, encoded_item)
+
+	// Add old GSI deletions to batch
+	if old, has_old := old_item.?; has_old {
+		gsi_del_err := gsi_batch_delete_entries(batch, table_name, old, metadata)
+		if gsi_del_err != .None {
+			return gsi_del_err
+		}
+	}
+
+	// Add new GSI writes to batch
+	gsi_write_err := gsi_batch_write_entries(batch, table_name, item, metadata)
+	if gsi_write_err != .None {
+		return gsi_write_err
+	}
+
+	return .None
+}
+
+// Add delete operation to batch (with GSI cleanup)
+@(private = "file")
+delete_item_batch :: proc(
+	batch: ^rocksdb.WriteBatch,
+	engine: ^Storage_Engine,
+	table_name: string,
+	key: Item,
+	metadata: ^Table_Metadata,
+	old_item: Maybe(Item),
+) -> Storage_Error {
+	key_struct, key_ok := key_from_item(key, metadata.key_schema)
+	if !key_ok {
+		return .Missing_Key_Attribute
+	}
+	defer key_destroy(&key_struct)
+
+	key_values, kv_ok := key_get_values(&key_struct)
+	if !kv_ok {
+		return .Invalid_Key
+	}
+
+	storage_key := build_data_key(table_name, key_values.pk, key_values.sk)
+	defer delete(storage_key)
+
+	// Add base item delete to batch
+	rocksdb.batch_delete(batch, storage_key)
+
+	// Add GSI deletions to batch
+	if old, has_old := old_item.?; has_old {
+		gsi_del_err := gsi_batch_delete_entries(batch, table_name, old, metadata)
+		if gsi_del_err != .None {
+			return gsi_del_err
+		}
+	}
+
+	return .None
+}
+
+// Add update operation to batch (with GSI maintenance)
+@(private = "file")
+update_item_batch :: proc(
+	batch: ^rocksdb.WriteBatch,
+	engine: ^Storage_Engine,
+	table_name: string,
+	key_item: Item,
+	plan: ^Update_Plan,
+	metadata: ^Table_Metadata,
+	old_item_pre: Maybe(Item),
+) -> Storage_Error {
+	key_struct, key_ok := key_from_item(key_item, metadata.key_schema)
+	if !key_ok {
+		return .Missing_Key_Attribute
+	}
+	defer key_destroy(&key_struct)
+
+	key_values, kv_ok := key_get_values(&key_struct)
+	if !kv_ok {
+		return .Invalid_Key
+	}
+
+	storage_key := build_data_key(table_name, key_values.pk, key_values.sk)
+	defer delete(storage_key)
+
+	// Start with existing item or create new
+	existing_item: Item
+	if old, has_old := old_item_pre.?; has_old {
+		existing_item = item_deep_copy(old)
+	} else {
+		existing_item = make(Item)
+		for ks in metadata.key_schema {
+			if val, found := key_item[ks.attribute_name]; found {
+				existing_item[strings.clone(ks.attribute_name)] = attr_value_deep_copy(val)
+			}
+		}
+	}
+	defer item_destroy(&existing_item)
+
+	// Apply update plan.
+	if exec_err := execute_update_plan(&existing_item, plan); exec_err != .None {
+		return .Validation_Error
+	}
+
+	// Encode updated item
+	encoded_item, encode_ok := encode(existing_item)
+	if !encode_ok {
+		return .Serialization_Error
+	}
+	defer delete(encoded_item)
+
+	// Add base item to batch
+	rocksdb.batch_put(batch, storage_key, encoded_item)
+
+	// Add old GSI deletions to batch
+	if old, has_old := old_item_pre.?; has_old {
+		gsi_del_err := gsi_batch_delete_entries(batch, table_name, old, metadata)
+		if gsi_del_err != .None {
+			return gsi_del_err
+		}
+	}
+
+	// Add new GSI writes to batch
+	gsi_write_err := gsi_batch_write_entries(batch, table_name, existing_item, metadata)
+	if gsi_write_err != .None {
+		return gsi_write_err
+	}
+
+	return .None
+}
+
+
 // ============================================================================
 // Internal storage operations that skip lock acquisition
 // (Used by transact_write_items which manages its own locking)
@@ -400,146 +631,6 @@ get_item_internal :: proc(
 	return item, .None
 }
 
-put_item_internal :: proc(
-	engine: ^Storage_Engine,
-	table_name: string,
-	item: Item,
-	metadata: ^Table_Metadata,
-) -> Storage_Error {
-	key_struct, key_ok := key_from_item(item, metadata.key_schema)
-	if !key_ok {
-		return .Missing_Key_Attribute
-	}
-	defer key_destroy(&key_struct)
-
-	key_values, kv_ok := key_get_values(&key_struct)
-	if !kv_ok {
-		return .Invalid_Key
-	}
-
-	storage_key := build_data_key(table_name, key_values.pk, key_values.sk)
-	defer delete(storage_key)
-
-	encoded_item, encode_ok := encode(item)
-	if !encode_ok {
-		return .Serialization_Error
-	}
-	defer delete(encoded_item)
-
-	put_err := rocksdb.db_put(&engine.db, storage_key, encoded_item)
-	if put_err != .None {
-		return .RocksDB_Error
-	}
-
-	return .None
-}
-
-delete_item_internal :: proc(
-	engine: ^Storage_Engine,
-	table_name: string,
-	key: Item,
-	metadata: ^Table_Metadata,
-) -> Storage_Error {
-	key_struct, key_ok := key_from_item(key, metadata.key_schema)
-	if !key_ok {
-		return .Missing_Key_Attribute
-	}
-	defer key_destroy(&key_struct)
-
-	key_values, kv_ok := key_get_values(&key_struct)
-	if !kv_ok {
-		return .Invalid_Key
-	}
-
-	storage_key := build_data_key(table_name, key_values.pk, key_values.sk)
-	defer delete(storage_key)
-
-	del_err := rocksdb.db_delete(&engine.db, storage_key)
-	if del_err != .None {
-		return .RocksDB_Error
-	}
-
-	return .None
-}
-
-update_item_internal :: proc(
-	engine: ^Storage_Engine,
-	table_name: string,
-	key_item: Item,
-	plan: ^Update_Plan,
-	metadata: ^Table_Metadata,
-) -> (old_item: Maybe(Item), new_item: Maybe(Item), err: Storage_Error) {
-	key_struct, key_ok := key_from_item(key_item, metadata.key_schema)
-	if !key_ok {
-		return nil, nil, .Missing_Key_Attribute
-	}
-	defer key_destroy(&key_struct)
-
-	key_values, kv_ok := key_get_values(&key_struct)
-	if !kv_ok {
-		return nil, nil, .Invalid_Key
-	}
-
-	storage_key := build_data_key(table_name, key_values.pk, key_values.sk)
-	defer delete(storage_key)
-
-	// Fetch existing item
-	existing_encoded, get_err := rocksdb.db_get(&engine.db, storage_key)
-	existing_item: Item
-
-	if get_err == .None && existing_encoded != nil {
-		defer delete(existing_encoded)
-		decoded, decode_ok := decode(existing_encoded)
-		if !decode_ok {
-			return nil, nil, .Serialization_Error
-		}
-		existing_item = decoded
-		old_item = item_deep_copy(existing_item)
-	} else if get_err == .NotFound || existing_encoded == nil {
-		existing_item = make(Item)
-		for ks in metadata.key_schema {
-			if val, found := key_item[ks.attribute_name]; found {
-				existing_item[strings.clone(ks.attribute_name)] = attr_value_deep_copy(val)
-			}
-		}
-	} else {
-		return nil, nil, .RocksDB_Error
-	}
-
-	if !execute_update_plan(&existing_item, plan) {
-		item_destroy(&existing_item)
-		if old, has := old_item.?; has {
-			old_copy := old
-			item_destroy(&old_copy)
-		}
-		return nil, nil, .Invalid_Key
-	}
-
-	encoded_item, encode_ok := encode(existing_item)
-	if !encode_ok {
-		item_destroy(&existing_item)
-		if old, has := old_item.?; has {
-			old_copy := old
-			item_destroy(&old_copy)
-		}
-		return nil, nil, .Serialization_Error
-	}
-	defer delete(encoded_item)
-
-	put_err := rocksdb.db_put(&engine.db, storage_key, encoded_item)
-	if put_err != .None {
-		item_destroy(&existing_item)
-		if old, has := old_item.?; has {
-			old_copy := old
-			item_destroy(&old_copy)
-		}
-		return nil, nil, .RocksDB_Error
-	}
-
-	new_item = existing_item
-	return old_item, new_item, .None
-}
-
 // ============================================================================
 // TransactGetItems Types
 // ============================================================================
@@ -555,8 +646,12 @@ Transact_Get_Result :: struct {
 }
 
 transact_get_action_destroy :: proc(action: ^Transact_Get_Action) {
+	delete(action.table_name)
 	item_destroy(&action.key)
 	if proj, has := action.projection.?; has {
+		for path in proj {
+			delete(path)
+		}
 		delete(proj)
 	}
 }

dynamodb/types.odin

@@ -5,26 +5,25 @@ import "core:strings"
 
 // DynamoDB AttributeValue - the core data type
 Attribute_Value :: union {
-	String,        // S
-	Number,        // N (stored as string)
-	Binary,        // B (base64)
-	Bool,          // BOOL
-	Null,          // NULL
-	String_Set,    // SS
-	Number_Set,    // NS
-	Binary_Set,    // BS
-	List,          // L
-	Map,           // M
+	String,         // S
+	DDB_Number,     // N — decimal-preserving numeric type
+	Binary,         // B (base64)
+	Bool,           // BOOL
+	Null,           // NULL
+	String_Set,     // SS
+	DDB_Number_Set, // NS
+	Binary_Set,     // BS
+	List,           // L
+	Map,            // M
 }
 
 String :: distinct string
-Number :: distinct string
 Binary :: distinct string
 Bool :: distinct bool
 Null :: distinct bool
 
 String_Set :: distinct []string
-Number_Set :: distinct []string
+DDB_Number_Set :: distinct []DDB_Number
 Binary_Set :: distinct []string
 List :: distinct []Attribute_Value
 Map :: distinct map[string]Attribute_Value
@@ -60,7 +59,7 @@ key_from_item :: proc(item: Item, key_schema: []Key_Schema_Element) -> (Key, boo
 
 		// Validate that key is a scalar type (S, N, or B)
 		#partial switch _ in attr {
-		case String, Number, Binary:
+		case String, DDB_Number, Binary:
 			// Valid key type
 		case:
 			return {}, false
@@ -116,12 +115,11 @@ key_get_values :: proc(key: ^Key) -> (Key_Values, bool) {
 	#partial switch v in key.pk {
 	case String:
 		pk_bytes = transmute([]byte)string(v)
-	case Number:
-		pk_bytes = transmute([]byte)string(v)
+	case DDB_Number:
+		pk_bytes = encode_ddb_number_for_sort(v)
 	case Binary:
 		pk_bytes = transmute([]byte)string(v)
 	case:
-		// Keys should only be scalar types (S, N, or B)
 		return {}, false
 	}
 
@@ -130,12 +128,11 @@ key_get_values :: proc(key: ^Key) -> (Key_Values, bool) {
 		#partial switch v in sk {
 		case String:
 			sk_bytes = transmute([]byte)string(v)
-		case Number:
-			sk_bytes = transmute([]byte)string(v)
+		case DDB_Number:
+			sk_bytes = encode_ddb_number_for_sort(v)
 		case Binary:
 			sk_bytes = transmute([]byte)string(v)
 		case:
-			// Keys should only be scalar types
 			return {}, false
 		}
 	}
@@ -366,13 +363,27 @@ error_to_response :: proc(err_type: DynamoDB_Error_Type, message: string) -> str
 
 // Build an Attribute_Value with the correct scalar type from raw bytes
 build_attribute_value_with_type :: proc(raw_bytes: []byte, attr_type: Scalar_Attribute_Type) -> Attribute_Value {
-	owned := strings.clone(string(raw_bytes))
 	switch attr_type {
-	case .S: return String(owned)
-	case .N: return Number(owned)
-	case .B: return Binary(owned)
+	case .S:
+		return String(strings.clone(string(raw_bytes)))
+	case .N:
+		// Key bytes are canonical-encoded via encode_ddb_number_for_sort.
+		// Decode them back to a DDB_Number.
+		ddb_num, ok := decode_ddb_number_from_sort(raw_bytes)
+		if ok {
+			return clone_ddb_number(ddb_num)
+		}
+		// Fallback: try interpreting as a plain numeric string
+		fallback_num, fb_ok := parse_ddb_number(string(raw_bytes))
+		if fb_ok {
+			return fallback_num
+		}
+		// Last resort — return as string (shouldn't happen)
+		return String(strings.clone(string(raw_bytes)))
+	case .B:
+		return Binary(strings.clone(string(raw_bytes)))
 	}
-	return String(owned)
+	return String(strings.clone(string(raw_bytes)))
 }
 
 // Deep copy an attribute value
@@ -380,8 +391,8 @@ attr_value_deep_copy :: proc(attr: Attribute_Value) -> Attribute_Value {
 	switch v in attr {
 	case String:
 		return String(strings.clone(string(v)))
-	case Number:
-		return Number(strings.clone(string(v)))
+	case DDB_Number:
+		return clone_ddb_number(v)
 	case Binary:
 		return Binary(strings.clone(string(v)))
 	case Bool:
@@ -394,12 +405,12 @@ attr_value_deep_copy :: proc(attr: Attribute_Value) -> Attribute_Value {
 			ss[i] = strings.clone(s)
 		}
 		return String_Set(ss)
-	case Number_Set:
-		ns := make([]string, len(v))
-		for n, i in v {
-			ns[i] = strings.clone(n)
+	case DDB_Number_Set:
+		ddb_ns := make([]DDB_Number, len(v))
+		for num, i in v {
+			ddb_ns[i] = clone_ddb_number(num)
 		}
-		return Number_Set(ns)
+		return DDB_Number_Set(ddb_ns)
 	case Binary_Set:
 		bs := make([]string, len(v))
 		for b, i in v {
@@ -427,8 +438,9 @@ attr_value_destroy :: proc(attr: ^Attribute_Value) {
 	switch v in attr {
 	case String:
 		delete(string(v))
-	case Number:
-		delete(string(v))
+	case DDB_Number:
+		delete(v.integer_part)
+		delete(v.fractional_part)
 	case Binary:
 		delete(string(v))
 	case String_Set:
@@ -437,12 +449,12 @@ attr_value_destroy :: proc(attr: ^Attribute_Value) {
 		}
 		slice := v
 		delete(slice)
-	case Number_Set:
-		for n in v {
-			delete(n)
+	case DDB_Number_Set:
+		for num in v {
+			delete(num.integer_part)
+			delete(num.fractional_part)
 		}
-		slice := v
-		delete(slice)
+		delete(v)
 	case Binary_Set:
 		for b in v {
 			delete(b)

dynamodb/update.odin

@@ -13,8 +13,6 @@
 package dynamodb
 
 import "core:encoding/json"
-import "core:fmt"
-import "core:strconv"
 import "core:strings"
 
 // ============================================================================
@@ -596,7 +594,23 @@ is_clause_keyword :: proc(tok: string) -> bool {
 // Execute Update Plan — apply mutations to an Item (in-place)
 // ============================================================================
 
-execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
+// Reasons an update plan can fail at execution time.
+// All of these map to ValidationException at the HTTP layer.
+Update_Exec_Error :: enum {
+	None,
+	// SET x = source +/- val: source attribute does not exist in the item
+	Operand_Not_Found,
+	// SET x = source +/- val: source or value attribute is not a Number
+	Operand_Not_Number,
+	// SET x = list_append(source, val): source attribute is not a List
+	Operand_Not_List,
+	// ADD path val: existing attribute is not a Number, String_Set, or Number_Set
+	Add_Type_Mismatch,
+	// ADD path val: value type does not match the existing set type
+	Add_Value_Type_Mismatch,
+}
+
+execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> Update_Exec_Error {
 	// Execute SET actions
 	for &action in plan.sets {
 		switch action.value_kind {
@@ -615,11 +629,11 @@ execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
 			if src, found := item[action.source]; found {
 				existing = src
 			} else {
-				return false // source attribute not found
+				return .Operand_Not_Found
 			}
 			result, add_ok := numeric_add(existing, action.value)
 			if !add_ok {
-				return false
+				return .Operand_Not_Number
 			}
 			if old, found := item[action.path]; found {
 				old_copy := old
@@ -634,11 +648,11 @@ execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
 			if src, found := item[action.source]; found {
 				existing = src
 			} else {
-				return false
+				return .Operand_Not_Found
 			}
 			result, sub_ok := numeric_subtract(existing, action.value)
 			if !sub_ok {
-				return false
+				return .Operand_Not_Number
 			}
 			if old, found := item[action.path]; found {
 				old_copy := old
@@ -666,7 +680,7 @@ execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
 				if l, is_list := src.(List); is_list {
 					existing_list = ([]Attribute_Value)(l)
 				} else {
-					return false
+					return .Operand_Not_List
 				}
 			} else {
 				existing_list = {}
@@ -676,7 +690,7 @@ execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
 			if l, is_list := action.value.(List); is_list {
 				append_list = ([]Attribute_Value)(l)
 			} else {
-				return false
+				return .Operand_Not_List
 			}
 
 			new_list := make([]Attribute_Value, len(existing_list) + len(append_list))
@@ -710,10 +724,10 @@ execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
 		if existing, found := item[action.path]; found {
 			// If existing is a number, add numerically
 			#partial switch v in existing {
-			case Number:
+			case DDB_Number:
 				result, add_ok := numeric_add(existing, action.value)
 				if !add_ok {
-					return false
+					return .Operand_Not_Number
 				}
 				old_copy := existing
 				attr_value_destroy(&old_copy)
@@ -729,22 +743,22 @@ execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
 					delete_key(item, action.path)
 					item[strings.clone(action.path)] = String_Set(merged)
 				} else {
-					return false
+					return .Add_Value_Type_Mismatch
 				}
 
-			case Number_Set:
-				if new_ns, is_ns := action.value.(Number_Set); is_ns {
-					merged := set_union_strings(([]string)(v), ([]string)(new_ns))
+			case DDB_Number_Set:
+				if new_ns, is_ns := action.value.(DDB_Number_Set); is_ns {
+					merged := set_union_ddb_numbers(([]DDB_Number)(v), ([]DDB_Number)(new_ns))
 					old_copy := existing
 					attr_value_destroy(&old_copy)
 					delete_key(item, action.path)
-					item[strings.clone(action.path)] = Number_Set(merged)
+					item[strings.clone(action.path)] = DDB_Number_Set(merged)
 				} else {
-					return false
+					return .Add_Value_Type_Mismatch
 				}
 
 			case:
-				return false
+				return .Add_Type_Mismatch
 			}
 		} else {
 			// Attribute doesn't exist — create it
@@ -769,14 +783,14 @@ execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
 					}
 				}
 
-			case Number_Set:
-				if del_ns, is_ns := action.value.(Number_Set); is_ns {
-					result := set_difference_strings(([]string)(v), ([]string)(del_ns))
+			case DDB_Number_Set:
+				if del_ns, is_ns := action.value.(DDB_Number_Set); is_ns {
+					result := set_difference_ddb_numbers(([]DDB_Number)(v), ([]DDB_Number)(del_ns))
 					old_copy := existing
 					attr_value_destroy(&old_copy)
 					delete_key(item, action.path)
 					if len(result) > 0 {
-						item[strings.clone(action.path)] = Number_Set(result)
+						item[strings.clone(action.path)] = DDB_Number_Set(result)
 					} else {
 						delete(result)
 					}
@@ -788,7 +802,7 @@ execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
 		}
 	}
 
-	return true
+	return .None
 }
 
 // ============================================================================
@@ -796,48 +810,31 @@ execute_update_plan :: proc(item: ^Item, plan: ^Update_Plan) -> bool {
 // ============================================================================
 
 numeric_add :: proc(a: Attribute_Value, b: Attribute_Value) -> (Attribute_Value, bool) {
-	a_num, a_ok := a.(Number)
-	b_num, b_ok := b.(Number)
+	a_num, a_ok := a.(DDB_Number)
+	b_num, b_ok := b.(DDB_Number)
 	if !a_ok || !b_ok {
 		return nil, false
 	}
 
-	a_val, a_parse := strconv.parse_f64(string(a_num))
-	b_val, b_parse := strconv.parse_f64(string(b_num))
-	if !a_parse || !b_parse {
+	result, result_ok := add_ddb_numbers(a_num, b_num)
+	if !result_ok {
 		return nil, false
 	}
-
-	result := a_val + b_val
-	result_str := format_number(result)
-	return Number(result_str), true
+	return result, true
 }
 
 numeric_subtract :: proc(a: Attribute_Value, b: Attribute_Value) -> (Attribute_Value, bool) {
-	a_num, a_ok := a.(Number)
-	b_num, b_ok := b.(Number)
+	a_num, a_ok := a.(DDB_Number)
+	b_num, b_ok := b.(DDB_Number)
 	if !a_ok || !b_ok {
 		return nil, false
 	}
 
-	a_val, a_parse := strconv.parse_f64(string(a_num))
-	b_val, b_parse := strconv.parse_f64(string(b_num))
-	if !a_parse || !b_parse {
+	result, result_ok := subtract_ddb_numbers(a_num, b_num)
+	if !result_ok {
 		return nil, false
 	}
-
-	result := a_val - b_val
-	result_str := format_number(result)
-	return Number(result_str), true
-}
-
-format_number :: proc(val: f64) -> string {
-	// If it's an integer, format without decimal point
-	int_val := i64(val)
-	if f64(int_val) == val {
-		return fmt.aprintf("%d", int_val)
-	}
-	return fmt.aprintf("%g", val)
+	return result, true
 }
 
 // ============================================================================
@@ -877,6 +874,52 @@ set_difference_strings :: proc(a: []string, b: []string) -> []string {
 	return result[:]
 }
 
+// Union of two DDB_Number slices (dedup by numeric equality)
+set_union_ddb_numbers :: proc(a: []DDB_Number, b: []DDB_Number) -> []DDB_Number {
+	result := make([dynamic]DDB_Number)
+
+	// Add all from a
+	for num in a {
+		append(&result, clone_ddb_number(num))
+	}
+
+	// Add from b if not already present
+	for num in b {
+		found := false
+		for existing in result {
+			if compare_ddb_numbers(existing, num) == 0 {
+				found = true
+				break
+			}
+		}
+		if !found {
+			append(&result, clone_ddb_number(num))
+		}
+	}
+
+	return result[:]
+}
+
+// Difference: elements in a that are NOT in b
+set_difference_ddb_numbers :: proc(a: []DDB_Number, b: []DDB_Number) -> []DDB_Number {
+	result := make([dynamic]DDB_Number)
+
+	for num in a {
+		in_b := false
+		for del in b {
+			if compare_ddb_numbers(num, del) == 0 {
+				in_b = true
+				break
+			}
+		}
+		if !in_b {
+			append(&result, clone_ddb_number(num))
+		}
+	}
+
+	return result[:]
+}
+
 // ============================================================================
 // Request Parsing Helper
 // ============================================================================
@@ -903,7 +946,7 @@ parse_update_expression_string :: proc(request_body: []byte) -> (expr: string, o
 		return
 	}
 
-	expr = string(ue_str)
+	expr = strings.clone(string(ue_str))
 	ok = true
 	return
 }
@@ -912,24 +955,24 @@ parse_update_expression_string :: proc(request_body: []byte) -> (expr: string, o
 parse_return_values :: proc(request_body: []byte) -> string {
 	data, parse_err := json.parse(request_body, allocator = context.temp_allocator)
 	if parse_err != nil {
-		return "NONE"
+		return strings.clone("NONE")
 	}
 	defer json.destroy_value(data)
 
 	root, root_ok := data.(json.Object)
 	if !root_ok {
-		return "NONE"
+		return strings.clone("NONE")
 	}
 
 	rv_val, found := root["ReturnValues"]
 	if !found {
-		return "NONE"
+		return strings.clone("NONE")
 	}
 
 	rv_str, str_ok := rv_val.(json.String)
 	if !str_ok {
-		return "NONE"
+		return strings.clone("NONE")
 	}
 
-	return string(rv_str)
+	return strings.clone(string(rv_str))
 }

dynamodb/update_item.odin

@@ -1,5 +1,3 @@
-// update_item.odin — Storage layer UpdateItem operation
-// This file lives in the dynamodb/ package alongside storage.odin
 package dynamodb
 
 import "core:strings"
@@ -8,6 +6,7 @@ import "../rocksdb"
 
 // UpdateItem — fetch existing item, apply update plan, write back
 // Uses EXCLUSIVE lock (write operation)
+// ATOMICITY: Uses WriteBatch to ensure base item + all GSI updates are atomic
 //
 // Returns:
 //   - old_item:  the item BEFORE mutations (if it existed), for ReturnValues
@@ -59,7 +58,7 @@ update_item :: proc(
 			return nil, nil, .Serialization_Error
 		}
 		existing_item = decoded
-		// Save old item for ReturnValues
+		// Save old item for ReturnValues (and for GSI cleanup)
 		old_item = item_deep_copy(existing_item)
 	} else if get_err == .NotFound || existing_encoded == nil {
 		// Item doesn't exist yet — start with just the key attributes
@@ -74,14 +73,14 @@ update_item :: proc(
 		return nil, nil, .RocksDB_Error
 	}
 
-	// Apply update plan
-	if !execute_update_plan(&existing_item, plan) {
+	// Apply update plan.
+	if exec_err := execute_update_plan(&existing_item, plan); exec_err != .None {
 		item_destroy(&existing_item)
 		if old, has := old_item.?; has {
 			old_copy := old
 			item_destroy(&old_copy)
 		}
-		return nil, nil, .Invalid_Key
+		return nil, nil, .Validation_Error
 	}
 
 	// Validate key attributes are still present and correct type
@@ -109,9 +108,46 @@ update_item :: proc(
 	}
 	defer delete(encoded_item)
 
-	// Write back to RocksDB
-	put_err := rocksdb.db_put(&engine.db, storage_key, encoded_item)
-	if put_err != .None {
+	// --- ATOMIC WRITE BATCH: base item + all GSI updates ---
+	batch, batch_err := rocksdb.batch_create()
+	if batch_err != .None {
+		item_destroy(&existing_item)
+		if old, has := old_item.?; has {
+			old_copy := old
+			item_destroy(&old_copy)
+		}
+		return nil, nil, .RocksDB_Error
+	}
+	defer rocksdb.batch_destroy(&batch)
+
+	// Add base item write to batch
+	rocksdb.batch_put(&batch, storage_key, encoded_item)
+
+	// Add old GSI entry deletions to batch (if item existed before)
+	if old, has := old_item.?; has {
+		gsi_del_err := gsi_batch_delete_entries(&batch, table_name, old, &metadata)
+		if gsi_del_err != .None {
+			item_destroy(&existing_item)
+			old_copy := old
+			item_destroy(&old_copy)
+			return nil, nil, gsi_del_err
+		}
+	}
+
+	// Add new GSI entry writes to batch
+	gsi_write_err := gsi_batch_write_entries(&batch, table_name, existing_item, &metadata)
+	if gsi_write_err != .None {
+		item_destroy(&existing_item)
+		if old, has := old_item.?; has {
+			old_copy := old
+			item_destroy(&old_copy)
+		}
+		return nil, nil, gsi_write_err
+	}
+
+	// Write batch atomically - ALL or NOTHING
+	write_err := rocksdb.batch_write(&engine.db, &batch)
+	if write_err != .None {
 		item_destroy(&existing_item)
 		if old, has := old_item.?; has {
 			old_copy := old
@@ -120,12 +156,6 @@ update_item :: proc(
 		return nil, nil, .RocksDB_Error
 	}
 
-	// --- GSI maintenance: delete old entries, write new entries ---
-	if old, has := old_item.?; has {
-		gsi_delete_entries(engine, table_name, old, &metadata)
-	}
-	gsi_write_entries(engine, table_name, existing_item, &metadata)
-
 	new_item = existing_item
 	return old_item, new_item, .None
 }

gsi_handlers.odin

@@ -259,7 +259,7 @@ parse_index_name :: proc(request_body: []byte) -> Maybe(string) {
 		return nil
 	}
 
-	return string(idx_str)
+	return strings.clone(string(idx_str))
 }
 
 // ============================================================================

http.odin

@@ -6,6 +6,7 @@ import vmem "core:mem/virtual"
 import "core:net"
 import "core:strings"
 import "core:strconv"
+import "core:thread"
 
 // HTTP Method enumeration
 HTTP_Method :: enum {
@@ -100,9 +101,16 @@ response_set_body :: proc(resp: ^HTTP_Response, data: []byte) {
 }
 
 // Request handler function type
-// Takes context pointer, request, and request-scoped allocator
 Request_Handler :: #type proc(ctx: rawptr, request: ^HTTP_Request, request_alloc: mem.Allocator) -> HTTP_Response
 
+// Parse error enum
+Parse_Error :: enum {
+	None,
+	Connection_Closed,
+	Invalid_Request,
+	Body_Too_Large,
+}
+
 // Server configuration
 Server_Config :: struct {
 	max_body_size:              int,  // default 100MB
@@ -122,6 +130,13 @@ default_server_config :: proc() -> Server_Config {
 	}
 }
 
+// Connection task data - passed to worker threads
+Connection_Task_Data :: struct {
+	server: ^Server,
+	conn:   net.TCP_Socket,
+	source: net.Endpoint,
+}
+
 // Server
 Server :: struct {
 	allocator:   mem.Allocator,
@@ -168,9 +183,12 @@ server_start :: proc(server: ^Server) -> bool {
 	server.socket = socket
 	server.running = true
 
-	fmt.printfln("HTTP server listening on %v", server.endpoint)
+	fmt.printfln("HTTP server listening on %v (thread-per-connection)", server.endpoint)
+	fmt.printfln("  Max body size: %d MB", server.config.max_body_size / (1024 * 1024))
+	fmt.printfln("  Max headers: %d", server.config.max_headers)
+	fmt.printfln("  Keep-alive: %v", server.config.enable_keep_alive)
 
-	// Accept loop
+	// Accept loop - spawn a thread for each connection
 	for server.running {
 		conn, source, accept_err := net.accept_tcp(socket)
 		if accept_err != nil {
@@ -180,9 +198,23 @@ server_start :: proc(server: ^Server) -> bool {
 			continue
 		}
 
-		// Handle connection in separate goroutine would go here
-		// For now, handle synchronously (should spawn thread)
-		handle_connection(server, conn, source)
+		// Allocate connection data
+		conn_data := new(Connection_Task_Data, server.allocator)
+		conn_data.server = server
+		conn_data.conn = conn
+		conn_data.source = source
+
+		// Spawn a new thread for this connection
+		t := thread.create(connection_worker_thread)
+		if t != nil {
+			t.init_context = context
+			t.data = conn_data
+			thread.start(t)
+		} else {
+			// Failed to create thread, close connection
+			net.close(conn)
+			free(conn_data, server.allocator)
+		}
 	}
 
 	return true
@@ -190,12 +222,33 @@ server_start :: proc(server: ^Server) -> bool {
 
 server_stop :: proc(server: ^Server) {
 	server.running = false
+
+	// Close listening socket
 	if sock, ok := server.socket.?; ok {
 		net.close(sock)
 		server.socket = nil
 	}
 }
 
+// Worker thread procedure
+connection_worker_thread :: proc(t: ^thread.Thread) {
+	defer thread.destroy(t)
+
+	conn_data := cast(^Connection_Task_Data)t.data
+	defer free(conn_data, conn_data.server.allocator)
+
+	handle_connection(conn_data.server, conn_data.conn, conn_data.source)
+}
+
+// Create error response
+make_error_response_simple :: proc(allocator: mem.Allocator, status: HTTP_Status, message: string) -> HTTP_Response {
+	response := response_init(allocator)
+	response_set_status(&response, status)
+	response_add_header(&response, "Content-Type", "text/plain")
+	response_set_body(&response, transmute([]byte)message)
+	return response
+}
+
 // Handle a single connection
 handle_connection :: proc(server: ^Server, conn: net.TCP_Socket, source: net.Endpoint) {
 	defer net.close(conn)
@@ -214,13 +267,26 @@ handle_connection :: proc(server: ^Server, conn: net.TCP_Socket, source: net.End
 
 		request_alloc := vmem.arena_allocator(&arena)
 
-		// TODO: Double check if we want *all* downstream allocations to use the request arena?
+		// Set request arena as context allocator for downstream allocations
 		old := context.allocator
 		context.allocator = request_alloc
 		defer context.allocator = old
 
-		request, parse_ok := parse_request(conn, request_alloc, server.config)
-		if !parse_ok {
+		request, parse_err := parse_request(conn, request_alloc, server.config)
+
+		// Handle parse errors
+		if parse_err != .None {
+			#partial switch parse_err {
+			case .Body_Too_Large:
+				// Send 413 Payload Too Large
+				response := make_error_response_simple(request_alloc, .Payload_Too_Large,
+					fmt.tprintf("Request body exceeds maximum size of %d bytes", server.config.max_body_size))
+				send_response(conn, &response, request_alloc)
+			case .Invalid_Request:
+				// Send 400 Bad Request
+				response := make_error_response_simple(request_alloc, .Bad_Request, "Invalid HTTP request")
+				send_response(conn, &response, request_alloc)
+			}
 			break
 		}
 
@@ -250,13 +316,13 @@ parse_request :: proc(
 	conn: net.TCP_Socket,
 	allocator: mem.Allocator,
 	config: Server_Config,
-) -> (HTTP_Request, bool) {
+) -> (HTTP_Request, Parse_Error) {
 	// Read request line and headers
 	buffer := make([]byte, config.read_buffer_size, allocator)
 
 	bytes_read, read_err := net.recv_tcp(conn, buffer)
 	if read_err != nil || bytes_read == 0 {
-		return {}, false
+		return {}, .Connection_Closed
 	}
 
 	request_data := buffer[:bytes_read]
@@ -264,7 +330,7 @@ parse_request :: proc(
 	// Find end of headers (\r\n\r\n)
 	header_end_idx := strings.index(string(request_data), "\r\n\r\n")
 	if header_end_idx < 0 {
-		return {}, false
+		return {}, .Invalid_Request
 	}
 
 	header_section := string(request_data[:header_end_idx])
@@ -273,13 +339,13 @@ parse_request :: proc(
 	// Parse request line
 	lines := strings.split_lines(header_section, allocator)
 	if len(lines) == 0 {
-		return {}, false
+		return {}, .Invalid_Request
 	}
 
 	request_line := lines[0]
 	parts := strings.split(request_line, " ", allocator)
 	if len(parts) < 3 {
-		return {}, false
+		return {}, .Invalid_Request
 	}
 
 	method := method_from_string(parts[0])
@@ -305,6 +371,11 @@ parse_request :: proc(
 			name  = strings.clone(name, allocator),
 			value = strings.clone(value, allocator),
 		})
+
+		// Check max headers limit
+		if len(headers) > config.max_headers {
+			return {}, .Invalid_Request
+		}
 	}
 
 	// Read body if Content-Length present
@@ -314,7 +385,12 @@ parse_request :: proc(
 	if cl, ok := content_length_header.?; ok {
 		content_length := strconv.parse_int(cl) or_else 0
 
-		if content_length > 0 && content_length <= config.max_body_size {
+		// Check if body size exceeds limit
+		if content_length > config.max_body_size {
+			return {}, .Body_Too_Large
+		}
+
+		if content_length > 0 {
 			// Check if we already have the body in buffer
 			existing_body := request_data[body_start:]
 
@@ -336,7 +412,7 @@ parse_request :: proc(
 
 					n, err := net.recv_tcp(conn, chunk)
 					if err != nil || n == 0 {
-						return {}, false
+						return {}, .Connection_Closed
 					}
 
 					copy(body[body_written:], chunk[:n])
@@ -352,7 +428,7 @@ parse_request :: proc(
 		path    = path,
 		headers = headers[:],
 		body    = body,
-	}, true
+	}, .None
 }
 
 // Helper to get header from slice

main.odin

@@ -13,6 +13,13 @@ Config :: struct {
 	port:     int,
 	data_dir: string,
 	verbose:  bool,
+
+	// HTTP server config
+	max_body_size:              int,
+	max_headers:                int,
+	read_buffer_size:           int,
+	enable_keep_alive:          bool,
+	max_requests_per_connection: int,
 }
 
 main :: proc() {
@@ -36,8 +43,14 @@ main :: proc() {
 	fmt.printfln("Storage engine initialized at %s", config.data_dir)
 	fmt.printfln("Starting DynamoDB-compatible server on %s:%d", config.host, config.port)
 
-	// Create HTTP server
-	server_config := default_server_config()
+	// Create HTTP server with config values
+	server_config := Server_Config{
+		max_body_size              = config.max_body_size,
+		max_headers                = config.max_headers,
+		read_buffer_size           = config.read_buffer_size,
+		enable_keep_alive          = config.enable_keep_alive,
+		max_requests_per_connection = config.max_requests_per_connection,
+	}
 
 	server, server_ok := server_init(
 		context.allocator,
@@ -190,6 +203,15 @@ handle_create_table :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Req
 		}
 	}
 
+	if gsi_val, found2 := root["GlobalSecondaryIndexes"]; found2 {
+		if gsi_arr, ok2 := gsi_val.(json.Array); ok2 && len(gsi_arr) > 0 {
+			if _, has := gsis.?; !has {
+				make_error_response(response, .ValidationException, "Invalid GlobalSecondaryIndexes definition")
+				return
+			}
+		}
+	}
+
 	// Create the table
 	desc, create_err := dynamodb.create_table(engine, string(table_name), key_schema, attr_defs, gsis)
 	if create_err != .None {
@@ -219,6 +241,7 @@ handle_delete_table :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Req
 		make_error_response(response, .ValidationException, "Invalid request or missing TableName")
 		return
 	}
+	defer delete(table_name)
 
 	err := dynamodb.delete_table(engine, table_name)
 	if err != .None {
@@ -241,6 +264,7 @@ handle_describe_table :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_R
 		make_error_response(response, .ValidationException, "Invalid request or missing TableName")
 		return
 	}
+	defer delete(table_name)
 
 	metadata, err := dynamodb.get_table_metadata(engine, table_name)
 	if err != .None {
@@ -266,16 +290,22 @@ handle_describe_table :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_R
 
 	for ks, i in metadata.key_schema {
 		if i > 0 do strings.write_string(&builder, ",")
-		fmt.sbprintf(&builder, `{"AttributeName":"%s","KeyType":"%s"}`,
-			ks.attribute_name, dynamodb.key_type_to_string(ks.key_type))
+		strings.write_string(&builder, `{"AttributeName":"`)
+		strings.write_string(&builder, ks.attribute_name)
+		strings.write_string(&builder, `","KeyType":"`)
+		strings.write_string(&builder, dynamodb.key_type_to_string(ks.key_type))
+		strings.write_string(&builder, `"}`)
 	}
 
 	strings.write_string(&builder, `],"AttributeDefinitions":[`)
 
 	for ad, i in metadata.attribute_definitions {
 		if i > 0 do strings.write_string(&builder, ",")
-		fmt.sbprintf(&builder, `{"AttributeName":"%s","AttributeType":"%s"}`,
-			ad.attribute_name, dynamodb.scalar_type_to_string(ad.attribute_type))
+		strings.write_string(&builder, `{"AttributeName":"`)
+		strings.write_string(&builder, ad.attribute_name)
+		strings.write_string(&builder, `","AttributeType":"`)
+		strings.write_string(&builder, dynamodb.scalar_type_to_string(ad.attribute_type))
+		strings.write_string(&builder, `"}`)
 	}
 
 	strings.write_string(&builder, `]`)
@@ -290,8 +320,11 @@ handle_describe_table :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_R
 			strings.write_string(&builder, `","KeySchema":[`)
 			for ks, ki in gsi.key_schema {
 				if ki > 0 do strings.write_string(&builder, ",")
-				fmt.sbprintf(&builder, `{"AttributeName":"%s","KeyType":"%s"}`,
-					ks.attribute_name, dynamodb.key_type_to_string(ks.key_type))
+				strings.write_string(&builder, `{"AttributeName":"`)
+				strings.write_string(&builder, ks.attribute_name)
+				strings.write_string(&builder, `","KeyType":"`)
+				strings.write_string(&builder, dynamodb.key_type_to_string(ks.key_type))
+				strings.write_string(&builder, `"}`)
 			}
 			strings.write_string(&builder, `],"Projection":{"ProjectionType":"`)
 			strings.write_string(&builder, projection_type_to_string(gsi.projection.projection_type))
@@ -340,6 +373,7 @@ handle_put_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request
 		make_error_response(response, .ValidationException, "Invalid request or missing TableName")
 		return
 	}
+	defer delete(table_name)
 
 	item, item_ok := dynamodb.parse_item_from_request(request.body)
 	if !item_ok {
@@ -349,8 +383,9 @@ handle_put_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request
 	defer dynamodb.item_destroy(&item)
 
 	// ---- ConditionExpression evaluation ----
-	_, has_condition := dynamodb.parse_condition_expression_string(request.body)
+	cond_str, has_condition := dynamodb.parse_condition_expression_string(request.body)
 	if has_condition {
+		defer delete(cond_str)
 		// Parse shared expression attributes
 		attr_names := dynamodb.parse_expression_attribute_names(request.body)
 		defer {
@@ -386,12 +421,21 @@ handle_put_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request
 			// If no explicit Key field, extract key from Item
 			// (PutItem doesn't have a Key field — the key is in the Item itself)
 			existing_maybe, get_err := dynamodb.get_item(engine, table_name, item)
-			if get_err != .None && get_err != .Table_Not_Found {
-				// Table not found is handled by put_item below
-				if get_err == .Missing_Key_Attribute || get_err == .Invalid_Key {
+			#partial switch get_err {
+				case .None:
+					// Item found or not found — both are fine, condition evaluates against
+					// whatever was returned (nil item = item doesn't exist).
+				case .Table_Not_Found:
+					// Table will be caught and reported properly by put_item below.
+				case .Missing_Key_Attribute, .Invalid_Key:
 					handle_storage_error(response, get_err)
 					return
-				}
+				case .RocksDB_Error, .Serialization_Error, .Internal_Error:
+					make_error_response(response, .InternalServerError, "Failed to fetch existing item")
+					return
+				case .Validation_Error, .Item_Not_Found:
+					// Item_Not_Found shouldn't reach here (get_item returns nil, .None),
+					// but treat defensively.
 			}
 			existing_item = existing_maybe
 		} else {
@@ -452,6 +496,7 @@ handle_get_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request
 		make_error_response(response, .ValidationException, "Invalid request or missing TableName")
 		return
 	}
+	defer delete(table_name)
 
 	key, key_ok := dynamodb.parse_key_from_request(request.body)
 	if !key_ok {
@@ -468,9 +513,17 @@ handle_get_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request
 
 	if item_val, has_item := item.?; has_item {
 		defer dynamodb.item_destroy(&item_val)
-		item_json := dynamodb.serialize_item(item_val)
-		resp := fmt.aprintf(`{"Item":%s}`, item_json)
-		response_set_body(response, transmute([]byte)resp)
+
+		// Build response directly to avoid intermediate string allocations
+		builder := strings.builder_make(context.allocator)
+		defer strings.builder_destroy(&builder)
+
+		strings.write_string(&builder, `{"Item":`)
+		dynamodb.serialize_item_to_builder(&builder, item_val)
+		strings.write_string(&builder, `}`)
+
+		resp_body := strings.clone(strings.to_string(builder))
+		response_set_body(response, transmute([]byte)resp_body)
 	} else {
 		response_set_body(response, transmute([]byte)string("{}"))
 	}
@@ -482,6 +535,7 @@ handle_delete_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Requ
 		make_error_response(response, .ValidationException, "Invalid request or missing TableName")
 		return
 	}
+	defer delete(table_name)
 
 	key, key_ok := dynamodb.parse_key_from_request(request.body)
 	if !key_ok {
@@ -521,11 +575,19 @@ handle_delete_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Requ
 
 		// Fetch existing item
 		existing_item, get_err := dynamodb.get_item(engine, table_name, key)
-		if get_err != .None && get_err != .Table_Not_Found {
-			if get_err == .Missing_Key_Attribute || get_err == .Invalid_Key {
+		#partial switch get_err {
+			case .None:
+				// Item found or not found — condition evaluates against whatever was returned.
+			case .Table_Not_Found:
+				// Table will be caught and reported properly by delete_item below.
+			case .Missing_Key_Attribute, .Invalid_Key:
 				handle_storage_error(response, get_err)
 				return
-			}
+			case .RocksDB_Error, .Serialization_Error, .Internal_Error:
+				make_error_response(response, .InternalServerError, "Failed to fetch existing item")
+				return
+			case .Validation_Error, .Item_Not_Found:
+				// Defensive — shouldn't reach here normally.
 		}
 		defer {
 			if ex, has_ex := existing_item.?; has_ex {
@@ -571,6 +633,7 @@ handle_update_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Requ
 		make_error_response(response, .ValidationException, "Invalid request or missing TableName")
 		return
 	}
+	defer delete(table_name)
 
 	// Parse Key
 	key_item, key_ok := dynamodb.parse_key_from_request(request.body)
@@ -586,6 +649,7 @@ handle_update_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Requ
 		make_error_response(response, .ValidationException, "Missing or invalid UpdateExpression")
 		return
 	}
+	defer delete(update_expr)
 
 	// Parse ExpressionAttributeNames and ExpressionAttributeValues
 	attr_names := dynamodb.parse_expression_attribute_names(request.body)
@@ -661,6 +725,7 @@ handle_update_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Requ
 
 	// Parse ReturnValues
 	return_values := dynamodb.parse_return_values(request.body)
+	defer delete(return_values)
 
 	// Execute update
 	old_item, new_item, err := dynamodb.update_item(engine, table_name, key_item, &plan)
@@ -680,51 +745,59 @@ handle_update_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Requ
 	}
 
 	// Build response based on ReturnValues
+	builder := strings.builder_make(context.allocator)
+	defer strings.builder_destroy(&builder)
+
 	switch return_values {
 	case "ALL_NEW":
 		if new_val, has := new_item.?; has {
-			item_json := dynamodb.serialize_item(new_val)
-			resp := fmt.aprintf(`{"Attributes":%s}`, item_json)
-			response_set_body(response, transmute([]byte)resp)
+			strings.write_string(&builder, `{"Attributes":`)
+			dynamodb.serialize_item_to_builder(&builder, new_val)
+			strings.write_string(&builder, `}`)
 		} else {
-			response_set_body(response, transmute([]byte)string("{}"))
+			strings.write_string(&builder, `{}`)
 		}
 
 	case "ALL_OLD":
 		if old, has := old_item.?; has {
-			item_json := dynamodb.serialize_item(old)
-			resp := fmt.aprintf(`{"Attributes":%s}`, item_json)
-			response_set_body(response, transmute([]byte)resp)
+			strings.write_string(&builder, `{"Attributes":`)
+			dynamodb.serialize_item_to_builder(&builder, old)
+			strings.write_string(&builder, `}`)
 		} else {
-			response_set_body(response, transmute([]byte)string("{}"))
+			strings.write_string(&builder, `{}`)
 		}
 
 	case "UPDATED_NEW":
 		if new_val, has := new_item.?; has {
 			filtered := filter_updated_attributes(new_val, &plan)
 			defer dynamodb.item_destroy(&filtered)
-			item_json := dynamodb.serialize_item(filtered)
-			resp := fmt.aprintf(`{"Attributes":%s}`, item_json)
-			response_set_body(response, transmute([]byte)resp)
+
+			strings.write_string(&builder, `{"Attributes":`)
+			dynamodb.serialize_item_to_builder(&builder, filtered)
+			strings.write_string(&builder, `}`)
 		} else {
-			response_set_body(response, transmute([]byte)string("{}"))
+			strings.write_string(&builder, `{}`)
 		}
 
 	case "UPDATED_OLD":
 		if old, has := old_item.?; has {
 			filtered := filter_updated_attributes(old, &plan)
 			defer dynamodb.item_destroy(&filtered)
-			item_json := dynamodb.serialize_item(filtered)
-			resp := fmt.aprintf(`{"Attributes":%s}`, item_json)
-			response_set_body(response, transmute([]byte)resp)
+
+			strings.write_string(&builder, `{"Attributes":`)
+			dynamodb.serialize_item_to_builder(&builder, filtered)
+			strings.write_string(&builder, `}`)
 		} else {
-			response_set_body(response, transmute([]byte)string("{}"))
+			strings.write_string(&builder, `{}`)
 		}
 
 	case:
 		// "NONE" or default
-		response_set_body(response, transmute([]byte)string("{}"))
+		strings.write_string(&builder, `{}`)
 	}
+
+	resp_body := strings.clone(strings.to_string(builder))
+	response_set_body(response, transmute([]byte)resp_body)
 }
 
 handle_batch_write_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, response: ^HTTP_Response) {
@@ -872,7 +945,7 @@ handle_batch_write_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP
 		}
 
 		append(&table_requests, dynamodb.Batch_Write_Table_Request{
-			table_name = string(table_name),
+			table_name = strings.clone(string(table_name)),
 			requests   = requests[:],
 		})
 	}
@@ -917,9 +990,13 @@ handle_batch_write_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP
 			item_json := dynamodb.serialize_item(req.item)
 			switch req.type {
 			case .Put:
-				fmt.sbprintf(&builder, `{"PutRequest":{"Item":%s}}`, item_json)
+				strings.write_string(&builder, `{"PutRequest":{"Item":`)
+				strings.write_string(&builder, item_json)
+				strings.write_string(&builder, "}}")
 			case .Delete:
-				fmt.sbprintf(&builder, `{"DeleteRequest":{"Key":%s}}`, item_json)
+				strings.write_string(&builder, `{"DeleteRequest":{"Key":`)
+				strings.write_string(&builder, item_json)
+				strings.write_string(&builder, "}}")
 			}
 		}
 
@@ -1010,7 +1087,7 @@ handle_batch_get_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_R
 		}
 
 		append(&table_requests, dynamodb.Batch_Get_Table_Request{
-			table_name = string(table_name),
+			table_name = strings.clone(string(table_name)),
 			keys       = keys[:],
 		})
 	}
@@ -1037,7 +1114,9 @@ handle_batch_get_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_R
 	defer dynamodb.batch_get_result_destroy(&result)
 
 	// Build response
-	builder := strings.builder_make()
+	builder := strings.builder_make(context.allocator)
+	defer strings.builder_destroy(&builder)
+
 	strings.write_string(&builder, `{"Responses":{`)
 
 	for table_result, ti in result.responses {
@@ -1050,8 +1129,7 @@ handle_batch_get_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_R
 			if ii > 0 {
 				strings.write_string(&builder, ",")
 			}
-			item_json := dynamodb.serialize_item(item)
-			strings.write_string(&builder, item_json)
+			dynamodb.serialize_item_to_builder(&builder, item)
 		}
 
 		strings.write_string(&builder, "]")
@@ -1063,14 +1141,15 @@ handle_batch_get_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_R
 		if ti > 0 {
 			strings.write_string(&builder, ",")
 		}
-		fmt.sbprintf(&builder, `"%s":{"Keys":[`, table_req.table_name)
+		strings.write_string(&builder, `"`)
+		strings.write_string(&builder, table_req.table_name)
+		strings.write_string(&builder, `":{"Keys":["`)
 
 		for key, ki in table_req.keys {
 			if ki > 0 {
 				strings.write_string(&builder, ",")
 			}
-			key_json := dynamodb.serialize_item(key)
-			strings.write_string(&builder, key_json)
+			dynamodb.serialize_item_to_builder(&builder, key)
 		}
 
 		strings.write_string(&builder, "]}")
@@ -1078,7 +1157,8 @@ handle_batch_get_item :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_R
 
 	strings.write_string(&builder, "}}")
 
-	resp_body := strings.to_string(builder)
+	// clone the god damn string
+	resp_body := strings.clone(strings.to_string(builder))
 	response_set_body(response, transmute([]byte)resp_body)
 }
 
@@ -1093,9 +1173,15 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 		make_error_response(response, .ValidationException, "Invalid request or missing TableName")
 		return
 	}
+	defer delete(table_name)
 
 	// Grab index name from request body
 	index_name := parse_index_name(request.body)
+	defer {
+		if idx, has := index_name.?; has {
+			delete(idx)
+		}
+	}
 
 	// Fetch table metadata early for ExclusiveStartKey parsing
 	metadata, meta_err := dynamodb.get_table_metadata(engine, table_name)
@@ -1133,11 +1219,15 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 	}
 
 	// Parse ExclusiveStartKey
-	exclusive_start_key, esk_ok := dynamodb.parse_exclusive_start_key(
+	exclusive_start_key, esk_ok, esk_body_err := dynamodb.parse_exclusive_start_key(
 		request.body, table_name, metadata.key_schema,
 	)
 	if !esk_ok {
-		make_error_response(response, .ValidationException, "Invalid ExclusiveStartKey")
+		if esk_body_err {
+			make_error_response(response, .SerializationException, "Request body is not valid JSON")
+		} else {
+			make_error_response(response, .ValidationException, "Invalid ExclusiveStartKey")
+		}
 		return
 	}
 	defer {
@@ -1165,7 +1255,11 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 		}
 	}
 
-	attr_values, _ := dynamodb.parse_expression_attribute_values(request.body)
+	attr_values, vals_ok := dynamodb.parse_expression_attribute_values(request.body)
+	if !vals_ok {
+		make_error_response(response, .ValidationException, "Invalid ExpressionAttributeValues")
+		return
+	}
 	defer {
 		for k, v in attr_values {
 			delete(k)
@@ -1177,15 +1271,30 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 
 	// ---- GSI query path ----
 	if idx_name, has_idx := index_name.?; has_idx {
-		_, gsi_found := dynamodb.find_gsi(&metadata, idx_name)
+		gsi, gsi_found := dynamodb.find_gsi(&metadata, idx_name)
 		if !gsi_found {
 			make_error_response(response, .ValidationException,
 				fmt.tprintf("The table does not have the specified index: %s", idx_name))
 			return
 		}
 
+		esk_gsi, esk_gsi_ok, esk_gsi_body_err := dynamodb.parse_exclusive_start_key_gsi(
+			request.body, table_name, &metadata, gsi,
+		)
+		if !esk_gsi_ok {
+			if esk_gsi_body_err {
+				make_error_response(response, .SerializationException, "Request body is not valid JSON")
+			} else {
+				make_error_response(response, .ValidationException, "Invalid ExclusiveStartKey")
+			}
+			return
+		}
+		defer {
+			if k, ok_gsi := esk_gsi.?; ok_gsi { delete(k) }
+		}
+
 		result, err := dynamodb.gsi_query(engine, table_name, idx_name,
-			pk_owned, exclusive_start_key, limit, sk_condition)
+			pk_owned, esk_gsi, limit, sk_condition)
 		if err != .None {
 			handle_storage_error(response, err)
 			return
@@ -1193,7 +1302,11 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 		defer dynamodb.query_result_destroy(&result)
 
 		// Apply FilterExpression
-		filtered_items := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
+		filtered_items, filter_ok := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
+		if !filter_ok {
+			make_error_response(response, .ValidationException, "Invalid FilterExpression")
+			return
+		}
 		scanned_count := len(result.items)
 
 		// Apply ProjectionExpression
@@ -1220,7 +1333,7 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 		}
 
 		write_items_response_with_pagination_ex(
-			response, final_items, result.last_evaluated_key, &metadata, scanned_count,
+			response, final_items, result.last_evaluated_key, &metadata, scanned_count, gsi,
 		)
 
 		if has_proj && len(projection) > 0 {
@@ -1241,7 +1354,11 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 	defer dynamodb.query_result_destroy(&result)
 
 	// ---- Apply FilterExpression (post-query filter) ----
-	filtered_items := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
+	filtered_items, filter_ok := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
+	if !filter_ok {
+		make_error_response(response, .ValidationException, "Invalid FilterExpression")
+		return
+	}
 	scanned_count := len(result.items)
 
 	// ---- Apply ProjectionExpression ----
@@ -1288,9 +1405,15 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 		make_error_response(response, .ValidationException, "Invalid request or missing TableName")
 		return
 	}
+	defer delete(table_name)
 
 	// Grab index name from request body
 	index_name := parse_index_name(request.body)
+	defer {
+		if idx, has := index_name.?; has {
+			delete(idx)
+		}
+	}
 
 	metadata, meta_err := dynamodb.get_table_metadata(engine, table_name)
 	if meta_err != .None {
@@ -1304,11 +1427,15 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 		limit = 100
 	}
 
-	exclusive_start_key, esk_ok := dynamodb.parse_exclusive_start_key(
+	exclusive_start_key, esk_ok, esk_body_err := dynamodb.parse_exclusive_start_key(
 		request.body, table_name, metadata.key_schema,
 	)
 	if !esk_ok {
-		make_error_response(response, .ValidationException, "Invalid ExclusiveStartKey")
+		if esk_body_err {
+			make_error_response(response, .SerializationException, "Request body is not valid JSON")
+		} else {
+			make_error_response(response, .ValidationException, "Invalid ExclusiveStartKey")
+		}
 		return
 	}
 	defer {
@@ -1330,7 +1457,11 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 		}
 	}
 
-	attr_values, _ := dynamodb.parse_expression_attribute_values(request.body)
+	attr_values, vals_ok := dynamodb.parse_expression_attribute_values(request.body)
+	if !vals_ok {
+		make_error_response(response, .ValidationException, "Invalid ExpressionAttributeValues")
+		return
+	}
 	defer {
 		for k, v in attr_values {
 			delete(k)
@@ -1342,23 +1473,44 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 
 	// ---- GSI scan path ----
 	if idx_name, has_idx := index_name.?; has_idx {
-		_, gsi_found := dynamodb.find_gsi(&metadata, idx_name)
+		gsi, gsi_found := dynamodb.find_gsi(&metadata, idx_name)
 		if !gsi_found {
 			make_error_response(response, .ValidationException,
 				fmt.tprintf("The table does not have the specified index: %s", idx_name))
 			return
 		}
 
-		result, err := dynamodb.gsi_scan(engine, table_name, idx_name, exclusive_start_key, limit)
+		esk_gsi, esk_gsi_ok, esk_gsi_body_err := dynamodb.parse_exclusive_start_key_gsi(
+			request.body, table_name, &metadata, gsi,
+		)
+		if !esk_gsi_ok {
+			if esk_gsi_body_err {
+				make_error_response(response, .SerializationException, "Request body is not valid JSON")
+			} else {
+				make_error_response(response, .ValidationException, "Invalid ExclusiveStartKey")
+			}
+			return
+		}
+		defer {
+			if k, ok_gsi := esk_gsi.?; ok_gsi { delete(k) }
+		}
+
+		result, err := dynamodb.gsi_scan(engine, table_name, idx_name, esk_gsi, limit)
 		if err != .None {
 			handle_storage_error(response, err)
 			return
 		}
 		defer dynamodb.scan_result_destroy(&result)
 
-		filtered_items := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
+		// Apply FilterExpression
+		filtered_items, filter_ok := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
+		if !filter_ok {
+			make_error_response(response, .ValidationException, "Invalid FilterExpression")
+			return
+		}
 		scanned_count := len(result.items)
 
+		// Apply ProjectionExpression
 		projection, has_proj := dynamodb.parse_projection_expression(request.body, attr_names)
 		defer { // This block just frees the cloned string and projection slice
 			if has_proj && len(projection) > 0 {
@@ -1382,7 +1534,7 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 		}
 
 		write_items_response_with_pagination_ex(
-			response, final_items, result.last_evaluated_key, &metadata, scanned_count,
+			response, final_items, result.last_evaluated_key, &metadata, scanned_count, gsi,
 		)
 
 		if has_proj && len(projection) > 0 {
@@ -1402,8 +1554,12 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 	}
 	defer dynamodb.scan_result_destroy(&result)
 
-	// ---- Apply FilterExpression ----
-	filtered_items := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
+	// ---- Apply FilterExpression (post-scan filter) ----
+	filtered_items, filter_ok := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
+	if !filter_ok {
+		make_error_response(response, .ValidationException, "Invalid FilterExpression")
+		return
+	}
 	scanned_count := len(result.items)
 
 	// ---- Apply ProjectionExpression ----
@@ -1451,15 +1607,16 @@ apply_filter_to_items :: proc(
 	items: []dynamodb.Item,
 	attr_names: Maybe(map[string]string),
 	attr_values: map[string]dynamodb.Attribute_Value,
-) -> []dynamodb.Item {
+) -> (filtered_items: []dynamodb.Item, ok: bool) {
 	filter_expr, has_filter := dynamodb.parse_filter_expression_string(request_body)
 	if !has_filter {
-		return items // no filter, return as-is
+		return items, true
 	}
+	defer delete(filter_expr)
 
 	filter_node, filter_ok := dynamodb.parse_filter_expression(filter_expr, attr_names, attr_values)
 	if !filter_ok || filter_node == nil {
-		return items // failed to parse, return unfiltered
+		return nil, false
 	}
 	defer {
 		dynamodb.filter_node_destroy(filter_node)
@@ -1473,7 +1630,7 @@ apply_filter_to_items :: proc(
 		}
 	}
 
-	return filtered[:]
+	return filtered[:], true
 }
 
 // ============================================================================
@@ -1490,14 +1647,16 @@ write_items_response_with_pagination_ex :: proc(
 	last_evaluated_key_binary: Maybe([]byte),
 	metadata: ^dynamodb.Table_Metadata,
 	scanned_count: int,
+	gsi: ^dynamodb.Global_Secondary_Index = nil,  // ← NEW parameter
 ) {
-	builder := strings.builder_make()
+	builder := strings.builder_make(context.allocator)
+	defer strings.builder_destroy(&builder)
+
 	strings.write_string(&builder, `{"Items":[`)
 
 	for item, i in items {
 		if i > 0 do strings.write_string(&builder, ",")
-		item_json := dynamodb.serialize_item(item)
-		strings.write_string(&builder, item_json)
+		dynamodb.serialize_item_to_builder(&builder, item)
 	}
 
 	strings.write_string(&builder, `],"Count":`)
@@ -1506,7 +1665,16 @@ write_items_response_with_pagination_ex :: proc(
 	fmt.sbprintf(&builder, "%d", scanned_count)
 
 	if binary_key, has_last := last_evaluated_key_binary.?; has_last {
-		lek_json, lek_ok := dynamodb.serialize_last_evaluated_key(binary_key, metadata)
+		lek_json: string
+		lek_ok: bool
+
+		// Use GSI serializer if we have a GSI, otherwise use base table serializer
+		if gsi != nil {
+			lek_json, lek_ok = dynamodb.serialize_last_evaluated_key_gsi(binary_key, metadata, gsi)
+		} else {
+			lek_json, lek_ok = dynamodb.serialize_last_evaluated_key(binary_key, metadata)
+		}
+
 		if lek_ok {
 			strings.write_string(&builder, `,"LastEvaluatedKey":`)
 			strings.write_string(&builder, lek_json)
@@ -1515,7 +1683,7 @@ write_items_response_with_pagination_ex :: proc(
 
 	strings.write_string(&builder, "}")
 
-	resp_body := strings.to_string(builder)
+	resp_body := strings.clone(strings.to_string(builder))
 	response_set_body(response, transmute([]byte)resp_body)
 }
 
@@ -1535,13 +1703,15 @@ write_items_response_with_pagination :: proc(
 	last_evaluated_key_binary: Maybe([]byte),
 	metadata: ^dynamodb.Table_Metadata,
 ) {
-	builder := strings.builder_make()
+	builder := strings.builder_make(context.allocator)
+	defer strings.builder_destroy(&builder)
+
 	strings.write_string(&builder, `{"Items":[`)
 
+	// Use serialize_item_to_builder directly so we always get the correct response payload
 	for item, i in items {
 		if i > 0 do strings.write_string(&builder, ",")
-		item_json := dynamodb.serialize_item(item)
-		strings.write_string(&builder, item_json)
+		dynamodb.serialize_item_to_builder(&builder, item)
 	}
 
 	strings.write_string(&builder, `],"Count":`)
@@ -1549,20 +1719,18 @@ write_items_response_with_pagination :: proc(
 	strings.write_string(&builder, `,"ScannedCount":`)
 	fmt.sbprintf(&builder, "%d", len(items))
 
-	// Emit LastEvaluatedKey if the storage layer produced one
 	if binary_key, has_last := last_evaluated_key_binary.?; has_last {
 		lek_json, lek_ok := dynamodb.serialize_last_evaluated_key(binary_key, metadata)
 		if lek_ok {
 			strings.write_string(&builder, `,"LastEvaluatedKey":`)
 			strings.write_string(&builder, lek_json)
 		}
-		// If decoding fails we still return the items — just without a pagination token.
-		// The client will assume the scan/query is complete.
 	}
 
 	strings.write_string(&builder, "}")
 
-	resp_body := strings.to_string(builder)
+	// We have to Clone the string before passing to response_set_body
+	resp_body := strings.clone(strings.to_string(builder))
 	response_set_body(response, transmute([]byte)resp_body)
 }
 
@@ -1585,6 +1753,8 @@ handle_storage_error :: proc(response: ^HTTP_Response, err: dynamodb.Storage_Err
 		make_error_response(response, .ValidationException, "One or more required key attributes are missing")
 	case .Invalid_Key:
 		make_error_response(response, .ValidationException, "Invalid key: type mismatch or malformed key value")
+	case .Validation_Error:
+		make_error_response(response, .ValidationException, "Invalid request: type mismatch or incompatible operand")
 	case .Serialization_Error:
 		make_error_response(response, .InternalServerError, "Internal serialization error")
 	case .RocksDB_Error:
@@ -1891,14 +2061,20 @@ make_error_response :: proc(response: ^HTTP_Response, err_type: dynamodb.DynamoD
 
 parse_config :: proc() -> Config {
 	config := Config{
-		host = "0.0.0.0",
-		port = 8002,
-		data_dir = "./data",
-		verbose = false,
+		// Defaults
+		host                       = "0.0.0.0",
+		port                       = 8002,
+		data_dir                   = "./data",
+		verbose                    = false,
+		max_body_size              = 100 * 1024 * 1024, // 100 MB
+		max_headers                = 100,
+		read_buffer_size           = 8 * 1024,          // 8 KB
+		enable_keep_alive          = true,
+		max_requests_per_connection = 1000,
 	}
 
-	// Environment variables
-	if port_str, env_ok := os.lookup_env("JORMUN_PORT"); env_ok {
+	// Environment variables (lower priority)
+	if port_str, ok := os.lookup_env("JORMUN_PORT"); ok {
 		if port, parse_ok := strconv.parse_int(port_str); parse_ok {
 			config.port = port
 		}
@@ -1916,11 +2092,107 @@ parse_config :: proc() -> Config {
 		config.verbose = verbose == "1"
 	}
 
-	// TODO: Parse command line arguments
+	if max_body_str, ok := os.lookup_env("JORMUN_MAX_BODY_SIZE"); ok {
+		if max_body, parse_ok := strconv.parse_int(max_body_str); parse_ok {
+			config.max_body_size = max_body
+		}
+	}
+
+	// Command line arguments (highest priority)
+	args := os.args[1:] // Skip program name
+
+	for i := 0; i < len(args); i += 1 {
+		arg := args[i]
+
+		// Helper to get next arg value
+		get_value :: proc(args: []string, i: ^int) -> (string, bool) {
+			if i^ + 1 < len(args) {
+				i^ += 1
+				return args[i^], true
+			}
+			return "", false
+		}
+
+		switch arg {
+		case "--host", "-h":
+			if value, ok := get_value(args, &i); ok {
+				config.host = value
+			}
+		case "--port", "-p":
+			if value, ok := get_value(args, &i); ok {
+				if port, parse_ok := strconv.parse_int(value); parse_ok {
+					config.port = port
+				}
+			}
+		case "--data-dir", "-d":
+			if value, ok := get_value(args, &i); ok {
+				config.data_dir = value
+			}
+		case "--verbose", "-v":
+			config.verbose = true
+		case "--max-body-size":
+			if value, ok := get_value(args, &i); ok {
+				if size, parse_ok := strconv.parse_int(value); parse_ok {
+					config.max_body_size = size
+				}
+			}
+		case "--max-headers":
+			if value, ok := get_value(args, &i); ok {
+				if count, parse_ok := strconv.parse_int(value); parse_ok {
+					config.max_headers = count
+				}
+			}
+		case "--no-keep-alive":
+			config.enable_keep_alive = false
+		case "--help":
+			print_help()
+			os.exit(0)
+		}
+	}
 
 	return config
 }
 
+print_help :: proc() {
+	help_text := `
+JormunDB - DynamoDB-Compatible Database Server
+
+USAGE:
+    jormundb [OPTIONS]
+
+OPTIONS:
+    --host, -h <HOST>           Server bind address (default: 0.0.0.0)
+    --port, -p <PORT>           Server port (default: 8002)
+    --data-dir, -d <DIR>        Data directory path (default: ./data)
+    --verbose, -v               Enable verbose logging
+    --max-body-size <BYTES>     Maximum request body size in bytes (default: 104857600 = 100MB)
+    --max-headers <COUNT>       Maximum number of headers per request (default: 100)
+    --no-keep-alive             Disable HTTP keep-alive connections
+    --help                      Show this help message
+
+ENVIRONMENT VARIABLES:
+    JORMUN_HOST                 Same as --host
+    JORMUN_PORT                 Same as --port
+    JORMUN_DATA_DIR             Same as --data-dir
+    JORMUN_VERBOSE              Set to "1" to enable verbose mode
+    JORMUN_MAX_BODY_SIZE        Same as --max-body-size
+
+EXAMPLES:
+    # Start with default settings
+    jormundb
+
+    # Custom port and data directory
+    jormundb --port 9000 --data-dir /var/lib/jormundb
+
+    # Limit body size to 10MB
+    jormundb --max-body-size 10485760
+
+    # Use environment variables
+    JORMUN_PORT=9000 JORMUN_HOST=127.0.0.1 jormundb
+`
+	fmt.println(help_text)
+}
+
 print_banner :: proc(config: Config) {
 	banner := `
   ╔═══════════════════════════════════════════════╗

open_api_doc.yaml

@@ -0,0 +1,884 @@
+openapi: 3.0.3
+info:
+  title: JormunDB DynamoDB Wire API
+  version: 0.1.0
+  description: |
+    DynamoDB-compatible JSON-over-HTTP API implemented by JormunDB.
+    Requests are POSTed to a single endpoint (/) and routed by the required `X-Amz-Target` header.
+servers:
+  - url: http://localhost:8002
+
+paths:
+  /:
+    post:
+      summary: DynamoDB JSON API endpoint
+      description: |
+        Send DynamoDB JSON protocol requests to this endpoint and set `X-Amz-Target` to the operation name,
+        e.g. `DynamoDB_20120810.GetItem`. The request and response media type is typically
+        `application/x-amz-json-1.0`.
+      parameters:
+        - $ref: '#/components/parameters/XAmzTarget'
+        - $ref: '#/components/parameters/XAmzDate'
+        - $ref: '#/components/parameters/Authorization'
+        - $ref: '#/components/parameters/XAmzSecurityToken'
+        - $ref: '#/components/parameters/XAmzContentSha256'
+      requestBody:
+        required: true
+        content:
+          application/x-amz-json-1.0:
+            schema:
+              oneOf:
+                - $ref: '#/components/schemas/CreateTableRequest'
+                - $ref: '#/components/schemas/DeleteTableRequest'
+                - $ref: '#/components/schemas/DescribeTableRequest'
+                - $ref: '#/components/schemas/ListTablesRequest'
+                - $ref: '#/components/schemas/PutItemRequest'
+                - $ref: '#/components/schemas/GetItemRequest'
+                - $ref: '#/components/schemas/DeleteItemRequest'
+                - $ref: '#/components/schemas/UpdateItemRequest'
+                - $ref: '#/components/schemas/QueryRequest'
+                - $ref: '#/components/schemas/ScanRequest'
+                - $ref: '#/components/schemas/BatchWriteItemRequest'
+                - $ref: '#/components/schemas/BatchGetItemRequest'
+                - $ref: '#/components/schemas/TransactWriteItemsRequest'
+                - $ref: '#/components/schemas/TransactGetItemsRequest'
+            examples:
+              CreateTable:
+                summary: Create a table with a HASH key
+                value:
+                  TableName: ExampleTable
+                  KeySchema:
+                    - AttributeName: pk
+                      KeyType: HASH
+                  AttributeDefinitions:
+                    - AttributeName: pk
+                      AttributeType: S
+      responses:
+        '200':
+          description: Successful operation response
+          content:
+            application/x-amz-json-1.0:
+              schema:
+                oneOf:
+                  - $ref: '#/components/schemas/CreateTableResponse'
+                  - $ref: '#/components/schemas/DeleteTableResponse'
+                  - $ref: '#/components/schemas/DescribeTableResponse'
+                  - $ref: '#/components/schemas/ListTablesResponse'
+                  - $ref: '#/components/schemas/PutItemResponse'
+                  - $ref: '#/components/schemas/GetItemResponseUnion'
+                  - $ref: '#/components/schemas/DeleteItemResponse'
+                  - $ref: '#/components/schemas/UpdateItemResponseUnion'
+                  - $ref: '#/components/schemas/QueryResponse'
+                  - $ref: '#/components/schemas/ScanResponse'
+                  - $ref: '#/components/schemas/BatchWriteItemResponse'
+                  - $ref: '#/components/schemas/BatchGetItemResponse'
+                  - $ref: '#/components/schemas/TransactWriteItemsResponse'
+                  - $ref: '#/components/schemas/TransactGetItemsResponse'
+        '400':
+          description: Client error (ValidationException, SerializationException, etc.)
+          content:
+            application/x-amz-json-1.0:
+              schema:
+                oneOf:
+                  - $ref: '#/components/schemas/DynamoDbError'
+                  - $ref: '#/components/schemas/TransactionCanceledException'
+        '500':
+          description: Server error
+          content:
+            application/x-amz-json-1.0:
+              schema:
+                $ref: '#/components/schemas/DynamoDbError'
+
+components:
+  parameters:
+    XAmzTarget:
+      name: X-Amz-Target
+      in: header
+      required: true
+      description: |
+        DynamoDB JSON protocol operation selector.
+        JormunDB recognizes targets with the `DynamoDB_20120810.` prefix.
+        Note: `UpdateTable` may be recognized but not implemented.
+      schema:
+        type: string
+        enum:
+          - DynamoDB_20120810.CreateTable
+          - DynamoDB_20120810.DeleteTable
+          - DynamoDB_20120810.DescribeTable
+          - DynamoDB_20120810.ListTables
+          - DynamoDB_20120810.UpdateTable
+          - DynamoDB_20120810.PutItem
+          - DynamoDB_20120810.GetItem
+          - DynamoDB_20120810.DeleteItem
+          - DynamoDB_20120810.UpdateItem
+          - DynamoDB_20120810.Query
+          - DynamoDB_20120810.Scan
+          - DynamoDB_20120810.BatchGetItem
+          - DynamoDB_20120810.BatchWriteItem
+          - DynamoDB_20120810.TransactGetItems
+          - DynamoDB_20120810.TransactWriteItems
+      example: DynamoDB_20120810.GetItem
+
+    XAmzDate:
+      name: X-Amz-Date
+      in: header
+      required: false
+      schema:
+        type: string
+      description: Optional SigV4 timestamp header (kept for SDK compatibility).
+
+    Authorization:
+      name: Authorization
+      in: header
+      required: false
+      schema:
+        type: string
+      description: Optional SigV4 Authorization header (kept for SDK compatibility).
+
+    XAmzSecurityToken:
+      name: X-Amz-Security-Token
+      in: header
+      required: false
+      schema:
+        type: string
+      description: Optional SigV4 session token header (kept for SDK compatibility).
+
+    XAmzContentSha256:
+      name: X-Amz-Content-Sha256
+      in: header
+      required: false
+      schema:
+        type: string
+      description: Optional SigV4 payload hash header (kept for SDK compatibility).
+
+  schemas:
+    EmptyObject:
+      type: object
+      description: Empty JSON object.
+      additionalProperties: false
+
+    # -------------------------
+    # AttributeValue & helpers
+    # -------------------------
+    AttributeValue:
+      description: DynamoDB AttributeValue (JSON wire format).
+      type: object
+      minProperties: 1
+      maxProperties: 1
+      oneOf:
+        - $ref: '#/components/schemas/AttrS'
+        - $ref: '#/components/schemas/AttrN'
+        - $ref: '#/components/schemas/AttrB'
+        - $ref: '#/components/schemas/AttrBOOL'
+        - $ref: '#/components/schemas/AttrNULL'
+        - $ref: '#/components/schemas/AttrSS'
+        - $ref: '#/components/schemas/AttrNS'
+        - $ref: '#/components/schemas/AttrBS'
+        - $ref: '#/components/schemas/AttrL'
+        - $ref: '#/components/schemas/AttrM'
+
+    AttrS:
+      type: object
+      additionalProperties: false
+      required: [S]
+      properties:
+        S:
+          type: string
+          example: hello
+
+    AttrN:
+      type: object
+      additionalProperties: false
+      required: [N]
+      properties:
+        N:
+          type: string
+          description: Numeric values are encoded as strings in DynamoDB's JSON protocol.
+          example: "42"
+
+    AttrB:
+      type: object
+      additionalProperties: false
+      required: [B]
+      properties:
+        B:
+          type: string
+          description: Base64-encoded binary value.
+          example: AAECAwQ=
+
+    AttrBOOL:
+      type: object
+      additionalProperties: false
+      required: [BOOL]
+      properties:
+        BOOL:
+          type: boolean
+          example: true
+
+    AttrNULL:
+      type: object
+      additionalProperties: false
+      required: [NULL]
+      properties:
+        NULL:
+          type: boolean
+          enum: [true]
+          example: true
+
+    AttrSS:
+      type: object
+      additionalProperties: false
+      required: [SS]
+      properties:
+        SS:
+          type: array
+          items: { type: string }
+          example: [a, b]
+
+    AttrNS:
+      type: object
+      additionalProperties: false
+      required: [NS]
+      properties:
+        NS:
+          type: array
+          description: Numeric set values are encoded as strings.
+          items: { type: string }
+          example: ["1", "2"]
+
+    AttrBS:
+      type: object
+      additionalProperties: false
+      required: [BS]
+      properties:
+        BS:
+          type: array
+          description: Base64-encoded binary set values.
+          items: { type: string }
+          example: [AAE=, AgM=]
+
+    AttrL:
+      type: object
+      additionalProperties: false
+      required: [L]
+      properties:
+        L:
+          type: array
+          items:
+            $ref: '#/components/schemas/AttributeValue'
+
+    AttrM:
+      type: object
+      additionalProperties: false
+      required: [M]
+      properties:
+        M:
+          $ref: '#/components/schemas/AttributeMap'
+
+    AttributeMap:
+      type: object
+      additionalProperties:
+        $ref: '#/components/schemas/AttributeValue'
+      example:
+        pk: { S: "user#1" }
+        sk: { S: "meta" }
+        age: { N: "30" }
+
+    ExpressionAttributeNames:
+      type: object
+      additionalProperties: { type: string }
+      example:
+        "#pk": "pk"
+
+    ExpressionAttributeValues:
+      type: object
+      additionalProperties:
+        $ref: '#/components/schemas/AttributeValue'
+      example:
+        ":v": { S: "user#1" }
+
+    Key:
+      allOf:
+        - $ref: '#/components/schemas/AttributeMap'
+      description: Primary key map (HASH, optionally RANGE) encoded as an AttributeMap.
+
+    ReturnValues:
+      type: string
+      description: ReturnValues selector used by UpdateItem.
+      enum: [NONE, ALL_OLD, UPDATED_OLD, ALL_NEW, UPDATED_NEW]
+      example: ALL_NEW
+
+    # -------------------------
+    # Table shapes
+    # -------------------------
+    ScalarAttributeType:
+      type: string
+      enum: [S, N, B]
+      example: S
+
+    AttributeDefinition:
+      type: object
+      additionalProperties: false
+      required: [AttributeName, AttributeType]
+      properties:
+        AttributeName: { type: string }
+        AttributeType: { $ref: '#/components/schemas/ScalarAttributeType' }
+
+    KeyType:
+      type: string
+      enum: [HASH, RANGE]
+      example: HASH
+
+    KeySchemaElement:
+      type: object
+      additionalProperties: false
+      required: [AttributeName, KeyType]
+      properties:
+        AttributeName: { type: string }
+        KeyType: { $ref: '#/components/schemas/KeyType' }
+
+    ProjectionType:
+      type: string
+      enum: [KEYS_ONLY, INCLUDE, ALL]
+      example: ALL
+
+    Projection:
+      type: object
+      additionalProperties: false
+      required: [ProjectionType]
+      properties:
+        ProjectionType: { $ref: '#/components/schemas/ProjectionType' }
+        NonKeyAttributes:
+          type: array
+          items: { type: string }
+
+    GlobalSecondaryIndex:
+      type: object
+      additionalProperties: false
+      required: [IndexName, KeySchema, Projection]
+      properties:
+        IndexName: { type: string }
+        KeySchema:
+          type: array
+          items: { $ref: '#/components/schemas/KeySchemaElement' }
+          minItems: 1
+        Projection: { $ref: '#/components/schemas/Projection' }
+
+    TableStatus:
+      type: string
+      enum: [CREATING, UPDATING, DELETING, ACTIVE, ARCHIVING, ARCHIVED]
+      example: ACTIVE
+
+    TableDescription:
+      type: object
+      additionalProperties: false
+      required: [TableName, TableStatus]
+      properties:
+        TableName: { type: string }
+        TableStatus: { $ref: '#/components/schemas/TableStatus' }
+        CreationDateTime:
+          type: integer
+          format: int64
+          description: Unix epoch seconds.
+        KeySchema:
+          type: array
+          items: { $ref: '#/components/schemas/KeySchemaElement' }
+        AttributeDefinitions:
+          type: array
+          items: { $ref: '#/components/schemas/AttributeDefinition' }
+        GlobalSecondaryIndexes:
+          type: array
+          items:
+            allOf:
+              - $ref: '#/components/schemas/GlobalSecondaryIndex'
+              - type: object
+                properties:
+                  IndexStatus:
+                    type: string
+                    enum: [ACTIVE]
+
+    # -------------------------
+    # Error shapes
+    # -------------------------
+    DynamoDbError:
+      type: object
+      additionalProperties: false
+      required: [__type, message]
+      properties:
+        __type:
+          type: string
+          description: DynamoDB error type identifier.
+          example: com.amazonaws.dynamodb.v20120810#ValidationException
+        message:
+          type: string
+          example: Invalid request
+
+    TransactionCanceledException:
+      type: object
+      additionalProperties: false
+      required: [__type, message, CancellationReasons]
+      properties:
+        __type:
+          type: string
+          enum: [com.amazonaws.dynamodb.v20120810#TransactionCanceledException]
+        message:
+          type: string
+        CancellationReasons:
+          type: array
+          items:
+            type: object
+            additionalProperties: false
+            required: [Code, Message]
+            properties:
+              Code: { type: string, example: ConditionalCheckFailed }
+              Message: { type: string, example: The conditional request failed }
+
+    # -------------------------
+    # API: CreateTable
+    # -------------------------
+    CreateTableRequest:
+      type: object
+      additionalProperties: true
+      required: [TableName, KeySchema, AttributeDefinitions]
+      properties:
+        TableName: { type: string }
+        KeySchema:
+          type: array
+          items: { $ref: '#/components/schemas/KeySchemaElement' }
+          minItems: 1
+        AttributeDefinitions:
+          type: array
+          items: { $ref: '#/components/schemas/AttributeDefinition' }
+          minItems: 1
+        GlobalSecondaryIndexes:
+          type: array
+          items: { $ref: '#/components/schemas/GlobalSecondaryIndex' }
+      description: |
+        CreateTable request. JormunDB focuses on TableName, KeySchema, AttributeDefinitions, and optional GSI definitions.
+
+    CreateTableResponse:
+      type: object
+      additionalProperties: false
+      required: [TableDescription]
+      properties:
+        TableDescription:
+          type: object
+          additionalProperties: false
+          required: [TableName, TableStatus, CreationDateTime]
+          properties:
+            TableName: { type: string }
+            TableStatus: { $ref: '#/components/schemas/TableStatus' }
+            CreationDateTime: { type: integer, format: int64 }
+
+    # -------------------------
+    # API: DeleteTable / DescribeTable / ListTables
+    # -------------------------
+    DeleteTableRequest:
+      type: object
+      additionalProperties: true
+      required: [TableName]
+      properties:
+        TableName: { type: string }
+
+    DeleteTableResponse:
+      type: object
+      additionalProperties: false
+      required: [TableDescription]
+      properties:
+        TableDescription:
+          type: object
+          additionalProperties: false
+          required: [TableName, TableStatus]
+          properties:
+            TableName: { type: string }
+            TableStatus:
+              type: string
+              enum: [DELETING]
+
+    DescribeTableRequest:
+      type: object
+      additionalProperties: true
+      required: [TableName]
+      properties:
+        TableName: { type: string }
+
+    DescribeTableResponse:
+      type: object
+      additionalProperties: false
+      required: [Table]
+      properties:
+        Table: { $ref: '#/components/schemas/TableDescription' }
+
+    ListTablesRequest:
+      type: object
+      additionalProperties: true
+      description: ListTables request. JormunDB ignores request fields for this operation.
+
+    ListTablesResponse:
+      type: object
+      additionalProperties: false
+      required: [TableNames]
+      properties:
+        TableNames:
+          type: array
+          items: { type: string }
+
+    # -------------------------
+    # API: PutItem / GetItem / DeleteItem
+    # -------------------------
+    PutItemRequest:
+      type: object
+      additionalProperties: true
+      required: [TableName, Item]
+      properties:
+        TableName: { type: string }
+        Item: { $ref: '#/components/schemas/AttributeMap' }
+        ConditionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+        ExpressionAttributeValues: { $ref: '#/components/schemas/ExpressionAttributeValues' }
+
+    PutItemResponse:
+      $ref: '#/components/schemas/EmptyObject'
+
+    GetItemRequest:
+      type: object
+      additionalProperties: true
+      required: [TableName, Key]
+      properties:
+        TableName: { type: string }
+        Key: { $ref: '#/components/schemas/Key' }
+        ProjectionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+
+    GetItemResponse:
+      type: object
+      additionalProperties: false
+      required: [Item]
+      properties:
+        Item: { $ref: '#/components/schemas/AttributeMap' }
+
+    GetItemResponseUnion:
+      oneOf:
+        - $ref: '#/components/schemas/EmptyObject'
+        - $ref: '#/components/schemas/GetItemResponse'
+
+    DeleteItemRequest:
+      type: object
+      additionalProperties: true
+      required: [TableName, Key]
+      properties:
+        TableName: { type: string }
+        Key: { $ref: '#/components/schemas/Key' }
+        ConditionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+        ExpressionAttributeValues: { $ref: '#/components/schemas/ExpressionAttributeValues' }
+
+    DeleteItemResponse:
+      $ref: '#/components/schemas/EmptyObject'
+
+    # -------------------------
+    # API: UpdateItem
+    # -------------------------
+    UpdateItemRequest:
+      type: object
+      additionalProperties: true
+      required: [TableName, Key, UpdateExpression]
+      properties:
+        TableName: { type: string }
+        Key: { $ref: '#/components/schemas/Key' }
+        UpdateExpression: { type: string }
+        ConditionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+        ExpressionAttributeValues: { $ref: '#/components/schemas/ExpressionAttributeValues' }
+        ReturnValues: { $ref: '#/components/schemas/ReturnValues' }
+
+    UpdateItemResponse:
+      type: object
+      additionalProperties: false
+      required: [Attributes]
+      properties:
+        Attributes: { $ref: '#/components/schemas/AttributeMap' }
+
+    UpdateItemResponseUnion:
+      oneOf:
+        - $ref: '#/components/schemas/EmptyObject'
+        - $ref: '#/components/schemas/UpdateItemResponse'
+
+    # -------------------------
+    # API: Query / Scan
+    # -------------------------
+    QueryRequest:
+      type: object
+      additionalProperties: true
+      required: [TableName, KeyConditionExpression]
+      properties:
+        TableName: { type: string }
+        IndexName: { type: string }
+        KeyConditionExpression: { type: string }
+        FilterExpression: { type: string }
+        ProjectionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+        ExpressionAttributeValues: { $ref: '#/components/schemas/ExpressionAttributeValues' }
+        Limit:
+          type: integer
+          format: int32
+          minimum: 1
+          description: Maximum items to return (default 100 if omitted/0 in JormunDB).
+        ExclusiveStartKey: { $ref: '#/components/schemas/Key' }
+        ScanIndexForward:
+          type: boolean
+          description: Sort order for RANGE key queries (if applicable).
+
+    ScanRequest:
+      type: object
+      additionalProperties: true
+      required: [TableName]
+      properties:
+        TableName: { type: string }
+        IndexName: { type: string }
+        FilterExpression: { type: string }
+        ProjectionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+        ExpressionAttributeValues: { $ref: '#/components/schemas/ExpressionAttributeValues' }
+        Limit:
+          type: integer
+          format: int32
+          minimum: 1
+          description: Maximum items to return (default 100 if omitted/0 in JormunDB).
+        ExclusiveStartKey: { $ref: '#/components/schemas/Key' }
+
+    ItemsPage:
+      type: object
+      additionalProperties: false
+      required: [Items, Count, ScannedCount]
+      properties:
+        Items:
+          type: array
+          items: { $ref: '#/components/schemas/AttributeMap' }
+        Count:
+          type: integer
+          format: int32
+        ScannedCount:
+          type: integer
+          format: int32
+        LastEvaluatedKey:
+          $ref: '#/components/schemas/Key'
+
+    QueryResponse:
+      allOf:
+        - $ref: '#/components/schemas/ItemsPage'
+
+    ScanResponse:
+      allOf:
+        - $ref: '#/components/schemas/ItemsPage'
+
+    # -------------------------
+    # API: BatchWriteItem
+    # -------------------------
+    WriteRequest:
+      type: object
+      additionalProperties: false
+      properties:
+        PutRequest:
+          type: object
+          additionalProperties: false
+          required: [Item]
+          properties:
+            Item: { $ref: '#/components/schemas/AttributeMap' }
+        DeleteRequest:
+          type: object
+          additionalProperties: false
+          required: [Key]
+          properties:
+            Key: { $ref: '#/components/schemas/Key' }
+      oneOf:
+        - required: [PutRequest]
+        - required: [DeleteRequest]
+
+    BatchWriteItemRequest:
+      type: object
+      additionalProperties: true
+      required: [RequestItems]
+      properties:
+        RequestItems:
+          type: object
+          description: Map of table name to write requests.
+          additionalProperties:
+            type: array
+            items: { $ref: '#/components/schemas/WriteRequest' }
+
+    BatchWriteItemResponse:
+      type: object
+      additionalProperties: false
+      required: [UnprocessedItems]
+      properties:
+        UnprocessedItems:
+          type: object
+          additionalProperties:
+            type: array
+            items: { $ref: '#/components/schemas/WriteRequest' }
+
+    # -------------------------
+    # API: BatchGetItem
+    # -------------------------
+    KeysAndAttributes:
+      type: object
+      additionalProperties: true
+      required: [Keys]
+      properties:
+        Keys:
+          type: array
+          items: { $ref: '#/components/schemas/Key' }
+        ProjectionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+
+    BatchGetItemRequest:
+      type: object
+      additionalProperties: true
+      required: [RequestItems]
+      properties:
+        RequestItems:
+          type: object
+          additionalProperties:
+            $ref: '#/components/schemas/KeysAndAttributes'
+
+    BatchGetItemResponse:
+      type: object
+      additionalProperties: false
+      required: [Responses, UnprocessedKeys]
+      properties:
+        Responses:
+          type: object
+          additionalProperties:
+            type: array
+            items: { $ref: '#/components/schemas/AttributeMap' }
+        UnprocessedKeys:
+          type: object
+          additionalProperties:
+            $ref: '#/components/schemas/KeysAndAttributes'
+
+    # -------------------------
+    # API: TransactWriteItems / TransactGetItems
+    # -------------------------
+    TransactWriteItemsRequest:
+      type: object
+      additionalProperties: true
+      required: [TransactItems]
+      properties:
+        TransactItems:
+          type: array
+          minItems: 1
+          maxItems: 100
+          items:
+            $ref: '#/components/schemas/TransactWriteItem'
+
+    TransactWriteItem:
+      type: object
+      additionalProperties: false
+      oneOf:
+        - required: [Put]
+        - required: [Delete]
+        - required: [Update]
+        - required: [ConditionCheck]
+      properties:
+        Put:
+          $ref: '#/components/schemas/TransactPut'
+        Delete:
+          $ref: '#/components/schemas/TransactDelete'
+        Update:
+          $ref: '#/components/schemas/TransactUpdate'
+        ConditionCheck:
+          $ref: '#/components/schemas/TransactConditionCheck'
+
+    TransactPut:
+      type: object
+      additionalProperties: true
+      required: [TableName, Item]
+      properties:
+        TableName: { type: string }
+        Item: { $ref: '#/components/schemas/AttributeMap' }
+        ConditionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+        ExpressionAttributeValues: { $ref: '#/components/schemas/ExpressionAttributeValues' }
+
+    TransactDelete:
+      type: object
+      additionalProperties: true
+      required: [TableName, Key]
+      properties:
+        TableName: { type: string }
+        Key: { $ref: '#/components/schemas/Key' }
+        ConditionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+        ExpressionAttributeValues: { $ref: '#/components/schemas/ExpressionAttributeValues' }
+
+    TransactUpdate:
+      type: object
+      additionalProperties: true
+      required: [TableName, Key, UpdateExpression]
+      properties:
+        TableName: { type: string }
+        Key: { $ref: '#/components/schemas/Key' }
+        UpdateExpression: { type: string }
+        ConditionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+        ExpressionAttributeValues: { $ref: '#/components/schemas/ExpressionAttributeValues' }
+
+    TransactConditionCheck:
+      type: object
+      additionalProperties: true
+      required: [TableName, Key, ConditionExpression]
+      properties:
+        TableName: { type: string }
+        Key: { $ref: '#/components/schemas/Key' }
+        ConditionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+        ExpressionAttributeValues: { $ref: '#/components/schemas/ExpressionAttributeValues' }
+
+    TransactWriteItemsResponse:
+      $ref: '#/components/schemas/EmptyObject'
+
+    TransactGetItemsRequest:
+      type: object
+      additionalProperties: true
+      required: [TransactItems]
+      properties:
+        TransactItems:
+          type: array
+          minItems: 1
+          maxItems: 100
+          items:
+            type: object
+            additionalProperties: false
+            required: [Get]
+            properties:
+              Get:
+                $ref: '#/components/schemas/TransactGet'
+
+    TransactGet:
+      type: object
+      additionalProperties: true
+      required: [TableName, Key]
+      properties:
+        TableName: { type: string }
+        Key: { $ref: '#/components/schemas/Key' }
+        ProjectionExpression: { type: string }
+        ExpressionAttributeNames: { $ref: '#/components/schemas/ExpressionAttributeNames' }
+
+    TransactGetItemResult:
+      oneOf:
+        - $ref: '#/components/schemas/EmptyObject'
+        - type: object
+          additionalProperties: false
+          required: [Item]
+          properties:
+            Item: { $ref: '#/components/schemas/AttributeMap' }
+
+    TransactGetItemsResponse:
+      type: object
+      additionalProperties: false
+      required: [Responses]
+      properties:
+        Responses:
+          type: array
+          items: { $ref: '#/components/schemas/TransactGetItemResult' }

transact_handlers.odin

@@ -267,7 +267,7 @@ parse_transact_put_action :: proc(
 	if !tn_ok {
 		return {}, false
 	}
-	action.table_name = string(tn_str)
+	action.table_name = strings.clone(string(tn_str))
 
 	// Item
 	item_val, item_found := obj["Item"]
@@ -301,7 +301,7 @@ parse_transact_key_action :: proc(
 	if !tn_ok {
 		return {}, false
 	}
-	action.table_name = string(tn_str)
+	action.table_name = strings.clone(string(tn_str))
 
 	// Key
 	key_val, key_found := obj["Key"]
@@ -335,7 +335,7 @@ parse_transact_update_action :: proc(
 	if !tn_ok {
 		return {}, false
 	}
-	action.table_name = string(tn_str)
+	action.table_name = strings.clone(string(tn_str))
 
 	// Key
 	key_val, key_found := obj["Key"]
@@ -483,7 +483,9 @@ handle_transact_get_items :: proc(
 	}
 
 	// Build response
-	builder := strings.builder_make()
+	builder := strings.builder_make(context.allocator)
+	defer strings.builder_destroy(&builder)
+
 	strings.write_string(&builder, `{"Responses":[`)
 
 	for maybe_item, i in result.items {
@@ -492,8 +494,9 @@ handle_transact_get_items :: proc(
 		}
 
 		if item, has_item := maybe_item.?; has_item {
-			item_json := dynamodb.serialize_item(item)
-			fmt.sbprintf(&builder, `{{"Item":%s}}`, item_json)
+			strings.write_string(&builder, `{"Item":`)
+			dynamodb.serialize_item_to_builder(&builder, item)
+			strings.write_string(&builder, `}`)
 		} else {
 			strings.write_string(&builder, "{}")
 		}
@@ -501,7 +504,8 @@ handle_transact_get_items :: proc(
 
 	strings.write_string(&builder, "]}")
 
-	resp_body := strings.to_string(builder)
+	// Clone the string or we gonna have issues again
+	resp_body := strings.clone(strings.to_string(builder))
 	response_set_body(response, transmute([]byte)resp_body)
 }
 
@@ -519,7 +523,7 @@ parse_transact_get_action :: proc(obj: json.Object) -> (dynamodb.Transact_Get_Ac
 	if !tn_ok {
 		return {}, false
 	}
-	action.table_name = string(tn_str)
+	action.table_name = strings.clone(string(tn_str))
 
 	// Key
 	key_val, key_found := obj["Key"]