global secondary indexes

README.md

@@ -16,7 +16,7 @@
 
 JormunDB is a Self-Hosted DynamoDB replacement that speaks the DynamoDB wire protocol. Point your AWS SDK or CLI at it and use it as a drop-in replacement.
 
-**Why Odin?** The original Zig implementation suffered from explicit allocator threading. Where every function ended up needing an `allocator` parameter and every allocation needed `errdefer` cleanup. Odin's implicit context allocator system eliminates this ceremony. Just one `context.allocator = arena_allocator` at the request handler entry and everything downstream just works.
+**Why Odin?** The original Zig implementation suffered from explicit allocator threading. Where every function ended up needing an `allocator` parameter and every allocation needed `errdefer` cleanup. Odin's implicit context allocator system eliminates this ceremony. Just one `context.allocator = arena_allocator` at the request handler entry and it feels more like working with ctx in Go instead of filling out tax forms.
 
 ## Features
 

dynamodb/gsi.odin

@@ -0,0 +1,481 @@
+// Global Secondary Index (GSI) support
+//
+// DynamoDB GSI semantics:
+//   - GSI entries are maintained automatically on every write (put/delete/update)
+//   - Each GSI has its own key schema (partition key + optional sort key)
+//   - GSI keys are built from item attributes; if an item doesn't have the GSI
+//     key attribute(s), NO GSI entry is written (sparse index)
+//   - Projection controls which non-key attributes are stored in the GSI entry:
+//       ALL       → entire item is copied
+//       KEYS_ONLY → only table PK/SK + GSI PK/SK
+//       INCLUDE   → table keys + GSI keys + specified non-key attributes
+//   - Query on a GSI uses IndexName to route to the correct key prefix
+//
+// Storage layout:
+//   GSI key:   [0x03][table_name][index_name][gsi_pk_value][gsi_sk_value?]
+//   GSI value: TLV-encoded projected item (same binary format as regular items)
+//
+// Write path:
+//   put_item  → for each GSI, extract GSI key attrs from the NEW item, write GSI entry
+//   delete    → for each GSI, extract GSI key attrs from the OLD item, delete GSI entry
+//   update    → delete OLD GSI entries, write NEW GSI entries
+//
+package dynamodb
+
+import "core:slice"
+import "core:strings"
+import "../rocksdb"
+
+// ============================================================================
+// GSI Key Extraction
+//
+// Extracts the GSI partition key (and optional sort key) raw bytes from an item.
+// Returns false if the item doesn't have the required GSI PK attribute (sparse).
+// ============================================================================
+
+GSI_Key_Values :: struct {
+	pk:  []byte,
+	sk:  Maybe([]byte),
+}
+
+// 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).
+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
+		}
+
+		raw, raw_ok := attr_value_to_bytes(attr)
+		if !raw_ok {
+			if ks.key_type == .HASH {
+				return {}, false
+			}
+			continue
+		}
+
+		switch ks.key_type {
+		case .HASH:
+			result.pk = raw
+		case .RANGE:
+			result.sk = raw
+		}
+	}
+
+	return result, true
+}
+
+// Convert a scalar attribute value to its raw byte representation (borrowed).
+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 Binary:
+		return transmute([]byte)string(v), true
+	}
+	return nil, false
+}
+
+// ============================================================================
+// GSI Projection
+//
+// Build a projected copy of an item for storage in a GSI entry.
+// ============================================================================
+
+// Build the projected item for a GSI entry.
+// The result is a new Item that the caller owns.
+gsi_project_item :: proc(
+	item: Item,
+	gsi: ^Global_Secondary_Index,
+	table_key_schema: []Key_Schema_Element,
+) -> Item {
+	switch gsi.projection.projection_type {
+	case .ALL:
+		return item_deep_copy(item)
+
+	case .KEYS_ONLY:
+		projected := make(Item)
+		// Include table key attributes
+		for ks in table_key_schema {
+			if val, found := item[ks.attribute_name]; found {
+				projected[strings.clone(ks.attribute_name)] = attr_value_deep_copy(val)
+			}
+		}
+		// Include GSI key attributes
+		for ks in gsi.key_schema {
+			if _, already := projected[ks.attribute_name]; already {
+				continue // Already included as table key
+			}
+			if val, found := item[ks.attribute_name]; found {
+				projected[strings.clone(ks.attribute_name)] = attr_value_deep_copy(val)
+			}
+		}
+		return projected
+
+	case .INCLUDE:
+		projected := make(Item)
+		// Include table key attributes
+		for ks in table_key_schema {
+			if val, found := item[ks.attribute_name]; found {
+				projected[strings.clone(ks.attribute_name)] = attr_value_deep_copy(val)
+			}
+		}
+		// Include GSI key attributes
+		for ks in gsi.key_schema {
+			if _, already := projected[ks.attribute_name]; already {
+				continue
+			}
+			if val, found := item[ks.attribute_name]; found {
+				projected[strings.clone(ks.attribute_name)] = attr_value_deep_copy(val)
+			}
+		}
+		// Include specified non-key attributes
+		if nka, has_nka := gsi.projection.non_key_attributes.?; has_nka {
+			for attr_name in nka {
+				if _, already := projected[attr_name]; already {
+					continue
+				}
+				if val, found := item[attr_name]; found {
+					projected[strings.clone(attr_name)] = attr_value_deep_copy(val)
+				}
+			}
+		}
+		return projected
+	}
+
+	// Fallback: all
+	return item_deep_copy(item)
+}
+
+// ============================================================================
+// GSI Write Maintenance
+//
+// Called after a successful data write to maintain GSI entries.
+// Uses WriteBatch for atomicity (all GSI entries for one item in one batch).
+// ============================================================================
+
+// 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,
+	table_name: string,
+	item: Item,
+	metadata: ^Table_Metadata,
+) -> Storage_Error {
+	gsis, has_gsis := metadata.global_secondary_indexes.?
+	if !has_gsis || len(gsis) == 0 {
+		return .None
+	}
+
+	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
+		}
+
+		// Build GSI storage key
+		gsi_storage_key := build_gsi_key(table_name, gsi.index_name, gsi_kv.pk, gsi_kv.sk)
+		defer delete(gsi_storage_key)
+
+		// Build projected item
+		projected := gsi_project_item(item, &gsi, metadata.key_schema)
+		defer item_destroy(&projected)
+
+		// Encode projected item
+		encoded, encode_ok := encode(projected)
+		if !encode_ok {
+			return .Serialization_Error
+		}
+		defer delete(encoded)
+
+		// Write to RocksDB
+		put_err := rocksdb.db_put(&engine.db, gsi_storage_key, encoded)
+		if put_err != .None {
+			return .RocksDB_Error
+		}
+	}
+
+	return .None
+}
+
+// Delete GSI entries for an item across all GSIs.
+// Should be called BEFORE or AFTER the main data key is deleted.
+// Needs the OLD item to know which GSI keys to remove.
+gsi_delete_entries :: proc(
+	engine: ^Storage_Engine,
+	table_name: string,
+	old_item: Item,
+	metadata: ^Table_Metadata,
+) -> Storage_Error {
+	gsis, has_gsis := metadata.global_secondary_indexes.?
+	if !has_gsis || len(gsis) == 0 {
+		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
+		}
+
+		gsi_storage_key := build_gsi_key(table_name, gsi.index_name, gsi_kv.pk, gsi_kv.sk)
+		defer delete(gsi_storage_key)
+
+		del_err := rocksdb.db_delete(&engine.db, gsi_storage_key)
+		if del_err != .None {
+			return .RocksDB_Error
+		}
+	}
+
+	return .None
+}
+
+// ============================================================================
+// GSI Query
+//
+// Queries a GSI by partition key with optional sort key condition.
+// Mirrors the main table query() but uses GSI key prefix.
+// ============================================================================
+
+gsi_query :: proc(
+	engine: ^Storage_Engine,
+	table_name: string,
+	index_name: string,
+	partition_key_value: []byte,
+	exclusive_start_key: Maybe([]byte),
+	limit: int,
+	sk_condition: Maybe(Sort_Key_Condition) = nil,
+) -> (Query_Result, Storage_Error) {
+	// Build GSI partition prefix
+	prefix := build_gsi_partition_prefix(table_name, index_name, partition_key_value)
+	defer delete(prefix)
+
+	iter, iter_err := rocksdb.iter_create(&engine.db)
+	if iter_err != .None {
+		return {}, .RocksDB_Error
+	}
+	defer rocksdb.iter_destroy(&iter)
+
+	max_items := limit if limit > 0 else 1_000_000
+
+	// Seek to start position
+	if start_key, has_start := exclusive_start_key.?; has_start {
+		if has_prefix(start_key, prefix) {
+			rocksdb.iter_seek(&iter, start_key)
+			if rocksdb.iter_valid(&iter) {
+				rocksdb.iter_next(&iter)
+			}
+		} else {
+			rocksdb.iter_seek(&iter, prefix)
+		}
+	} else {
+		rocksdb.iter_seek(&iter, prefix)
+	}
+
+	items := make([dynamic]Item)
+	count := 0
+	last_key: Maybe([]byte) = nil
+	has_more := false
+
+	for rocksdb.iter_valid(&iter) {
+		key := rocksdb.iter_key(&iter)
+		if key == nil || !has_prefix(key, prefix) {
+			break
+		}
+
+		if count >= max_items {
+			has_more = true
+			break
+		}
+
+		value := rocksdb.iter_value(&iter)
+		if value == nil {
+			rocksdb.iter_next(&iter)
+			continue
+		}
+
+		item, decode_ok := decode(value)
+		if !decode_ok {
+			rocksdb.iter_next(&iter)
+			continue
+		}
+
+		// Sort key condition filtering
+		if skc, has_skc := sk_condition.?; has_skc {
+			if !evaluate_sort_key_condition(item, &skc) {
+				item_copy := item
+				item_destroy(&item_copy)
+				rocksdb.iter_next(&iter)
+				continue
+			}
+		}
+
+		append(&items, item)
+		count += 1
+
+		// Track key of last returned item
+		if prev_key, had_prev := last_key.?; had_prev {
+			delete(prev_key)
+		}
+		last_key = slice.clone(key)
+
+		rocksdb.iter_next(&iter)
+	}
+
+	// Only emit LastEvaluatedKey if there are more items
+	if !has_more {
+		if lk, had_lk := last_key.?; had_lk {
+			delete(lk)
+		}
+		last_key = nil
+	}
+
+	result_items := make([]Item, len(items))
+	copy(result_items, items[:])
+
+	return Query_Result{
+		items              = result_items,
+		last_evaluated_key = last_key,
+	}, .None
+}
+
+// ============================================================================
+// GSI Scan
+//
+// Scans all entries in a GSI (all partition keys under that index).
+// ============================================================================
+
+gsi_scan :: proc(
+	engine: ^Storage_Engine,
+	table_name: string,
+	index_name: string,
+	exclusive_start_key: Maybe([]byte),
+	limit: int,
+) -> (Scan_Result, Storage_Error) {
+	prefix := build_gsi_prefix(table_name, index_name)
+	defer delete(prefix)
+
+	iter, iter_err := rocksdb.iter_create(&engine.db)
+	if iter_err != .None {
+		return {}, .RocksDB_Error
+	}
+	defer rocksdb.iter_destroy(&iter)
+
+	max_items := limit if limit > 0 else 1_000_000
+
+	if start_key, has_start := exclusive_start_key.?; has_start {
+		if has_prefix(start_key, prefix) {
+			rocksdb.iter_seek(&iter, start_key)
+			if rocksdb.iter_valid(&iter) {
+				rocksdb.iter_next(&iter)
+			}
+		} else {
+			rocksdb.iter_seek(&iter, prefix)
+		}
+	} else {
+		rocksdb.iter_seek(&iter, prefix)
+	}
+
+	items := make([dynamic]Item)
+	count := 0
+	last_key: Maybe([]byte) = nil
+	has_more := false
+
+	for rocksdb.iter_valid(&iter) {
+		key := rocksdb.iter_key(&iter)
+		if key == nil || !has_prefix(key, prefix) {
+			break
+		}
+
+		if count >= max_items {
+			has_more = true
+			break
+		}
+
+		value := rocksdb.iter_value(&iter)
+		if value == nil {
+			rocksdb.iter_next(&iter)
+			continue
+		}
+
+		item, decode_ok := decode(value)
+		if !decode_ok {
+			rocksdb.iter_next(&iter)
+			continue
+		}
+
+		append(&items, item)
+		count += 1
+
+		if prev_key, had_prev := last_key.?; had_prev {
+			delete(prev_key)
+		}
+		last_key = slice.clone(key)
+
+		rocksdb.iter_next(&iter)
+	}
+
+	if !has_more {
+		if lk, had_lk := last_key.?; had_lk {
+			delete(lk)
+		}
+		last_key = nil
+	}
+
+	result_items := make([]Item, len(items))
+	copy(result_items, items[:])
+
+	return Scan_Result{
+		items              = result_items,
+		last_evaluated_key = last_key,
+	}, .None
+}
+
+// ============================================================================
+// GSI Metadata Lookup Helpers
+// ============================================================================
+
+// Find a GSI definition by index name in the table metadata.
+find_gsi :: proc(metadata: ^Table_Metadata, index_name: string) -> (^Global_Secondary_Index, bool) {
+	gsis, has_gsis := metadata.global_secondary_indexes.?
+	if !has_gsis {
+		return nil, false
+	}
+
+	for &gsi in gsis {
+		if gsi.index_name == index_name {
+			return &gsi, true
+		}
+	}
+
+	return nil, false
+}
+
+// Get the GSI's sort key attribute name (if any).
+gsi_get_sort_key_name :: proc(gsi: ^Global_Secondary_Index) -> Maybe(string) {
+	for ks in gsi.key_schema {
+		if ks.key_type == .RANGE {
+			return ks.attribute_name
+		}
+	}
+	return nil
+}
+
+// Get the GSI's partition key attribute name.
+gsi_get_partition_key_name :: proc(gsi: ^Global_Secondary_Index) -> Maybe(string) {
+	for ks in gsi.key_schema {
+		if ks.key_type == .HASH {
+			return ks.attribute_name
+		}
+	}
+	return nil
+}

dynamodb/gsi_metadata.odin

@@ -0,0 +1,187 @@
+// gsi_metadata.odin — GSI metadata parsing for serialize/deserialize_table_metadata
+//
+// Parses GSI definitions from the embedded JSON string stored in table metadata.
+// This file lives in the dynamodb/ package.
+package dynamodb
+
+import "core:encoding/json"
+import "core:mem"
+import "core:strings"
+
+// Parse GlobalSecondaryIndexes from a JSON string like:
+// [{"IndexName":"email-index","KeySchema":[{"AttributeName":"email","KeyType":"HASH"}],
+//   "Projection":{"ProjectionType":"ALL"}}]
+//
+// Allocates all strings with the given allocator (engine.allocator for long-lived data).
+parse_gsis_json :: proc(json_str: string, allocator: mem.Allocator) -> ([]Global_Secondary_Index, bool) {
+	data, parse_err := json.parse(transmute([]byte)json_str, allocator = context.temp_allocator)
+	if parse_err != nil {
+		return nil, false
+	}
+	defer json.destroy_value(data)
+
+	arr, ok := data.(json.Array)
+	if !ok {
+		return nil, false
+	}
+
+	if len(arr) == 0 {
+		return nil, true // Empty is valid
+	}
+
+	result := make([]Global_Secondary_Index, len(arr), allocator)
+
+	for elem, i in arr {
+		obj, obj_ok := elem.(json.Object)
+		if !obj_ok {
+			cleanup_gsis(result[:i], allocator)
+			delete(result, allocator)
+			return nil, false
+		}
+
+		gsi, gsi_ok := parse_single_gsi_json(obj, allocator)
+		if !gsi_ok {
+			cleanup_gsis(result[:i], allocator)
+			delete(result, allocator)
+			return nil, false
+		}
+
+		result[i] = gsi
+	}
+
+	return result, true
+}
+
+// Parse a single GSI object from JSON
+@(private = "file")
+parse_single_gsi_json :: proc(obj: json.Object, allocator: mem.Allocator) -> (Global_Secondary_Index, bool) {
+	gsi: Global_Secondary_Index
+
+	// IndexName
+	idx_val, idx_found := obj["IndexName"]
+	if !idx_found {
+		return {}, false
+	}
+	idx_str, idx_ok := idx_val.(json.String)
+	if !idx_ok {
+		return {}, false
+	}
+	gsi.index_name = strings.clone(string(idx_str), allocator)
+
+	// KeySchema
+	ks_val, ks_found := obj["KeySchema"]
+	if !ks_found {
+		delete(gsi.index_name, allocator)
+		return {}, false
+	}
+	ks_arr, ks_ok := ks_val.(json.Array)
+	if !ks_ok || len(ks_arr) == 0 || len(ks_arr) > 2 {
+		delete(gsi.index_name, allocator)
+		return {}, false
+	}
+
+	key_schema := make([]Key_Schema_Element, len(ks_arr), allocator)
+	for ks_elem, j in ks_arr {
+		ks_obj, kobj_ok := ks_elem.(json.Object)
+		if !kobj_ok {
+			for k in 0..<j {
+				delete(key_schema[k].attribute_name, allocator)
+			}
+			delete(key_schema, allocator)
+			delete(gsi.index_name, allocator)
+			return {}, false
+		}
+
+		an_val, an_found := ks_obj["AttributeName"]
+		if !an_found {
+			for k in 0..<j { delete(key_schema[k].attribute_name, allocator) }
+			delete(key_schema, allocator)
+			delete(gsi.index_name, allocator)
+			return {}, false
+		}
+		an_str, an_ok := an_val.(json.String)
+		if !an_ok {
+			for k in 0..<j { delete(key_schema[k].attribute_name, allocator) }
+			delete(key_schema, allocator)
+			delete(gsi.index_name, allocator)
+			return {}, false
+		}
+
+		kt_val, kt_found := ks_obj["KeyType"]
+		if !kt_found {
+			for k in 0..<j { delete(key_schema[k].attribute_name, allocator) }
+			delete(key_schema, allocator)
+			delete(gsi.index_name, allocator)
+			return {}, false
+		}
+		kt_str, kt_ok := kt_val.(json.String)
+		if !kt_ok {
+			for k in 0..<j { delete(key_schema[k].attribute_name, allocator) }
+			delete(key_schema, allocator)
+			delete(gsi.index_name, allocator)
+			return {}, false
+		}
+
+		kt, kt_parse_ok := key_type_from_string(string(kt_str))
+		if !kt_parse_ok {
+			for k in 0..<j { delete(key_schema[k].attribute_name, allocator) }
+			delete(key_schema, allocator)
+			delete(gsi.index_name, allocator)
+			return {}, false
+		}
+
+		key_schema[j] = Key_Schema_Element{
+			attribute_name = strings.clone(string(an_str), allocator),
+			key_type = kt,
+		}
+	}
+	gsi.key_schema = key_schema
+
+	// Projection
+	gsi.projection.projection_type = .ALL // default
+	if proj_val, proj_found := obj["Projection"]; proj_found {
+		if proj_obj, proj_ok := proj_val.(json.Object); proj_ok {
+			if pt_val, pt_found := proj_obj["ProjectionType"]; pt_found {
+				if pt_str, pt_ok := pt_val.(json.String); pt_ok {
+					switch string(pt_str) {
+					case "ALL":       gsi.projection.projection_type = .ALL
+					case "KEYS_ONLY": gsi.projection.projection_type = .KEYS_ONLY
+					case "INCLUDE":   gsi.projection.projection_type = .INCLUDE
+					}
+				}
+			}
+
+			// NonKeyAttributes
+			if nka_val, nka_found := proj_obj["NonKeyAttributes"]; nka_found {
+				if nka_arr, nka_ok := nka_val.(json.Array); nka_ok && len(nka_arr) > 0 {
+					nka := make([]string, len(nka_arr), allocator)
+					for attr_val, k in nka_arr {
+						if attr_str, attr_ok := attr_val.(json.String); attr_ok {
+							nka[k] = strings.clone(string(attr_str), allocator)
+						}
+					}
+					gsi.projection.non_key_attributes = nka
+				}
+			}
+		}
+	}
+
+	return gsi, true
+}
+
+// Clean up partially-constructed GSI array
+cleanup_gsis :: proc(gsis: []Global_Secondary_Index, allocator: mem.Allocator) {
+	for gsi in gsis {
+		delete(gsi.index_name, allocator)
+		for ks in gsi.key_schema {
+			delete(ks.attribute_name, allocator)
+		}
+		delete(gsi.key_schema, allocator)
+		if nka, has_nka := gsi.projection.non_key_attributes.?; has_nka {
+			for attr in nka {
+				delete(attr, allocator)
+			}
+			delete(nka, allocator)
+		}
+	}
+}

dynamodb/key_codec_gsi.odin

@@ -0,0 +1,94 @@
+// key_codec_gsi.odin — Additional key codec functions for GSI support
+//
+// These procedures complement key_codec.odin with prefix builders needed
+// for GSI scanning and querying. They follow the same encoding conventions:
+//   [entity_type][varint_len][segment_bytes]...
+//
+// Add the contents of this file to key_codec.odin (or keep as a separate file
+// in the dynamodb/ package).
+package dynamodb
+
+import "core:bytes"
+
+// Build GSI index prefix for scanning all entries in a GSI:
+//   [gsi][table_name][index_name]
+build_gsi_prefix :: proc(table_name: string, index_name: string) -> []byte {
+	buf: bytes.Buffer
+	bytes.buffer_init_allocator(&buf, 0, 256, context.allocator)
+
+	bytes.buffer_write_byte(&buf, u8(Entity_Type.GSI))
+
+	encode_varint(&buf, len(table_name))
+	bytes.buffer_write_string(&buf, table_name)
+
+	encode_varint(&buf, len(index_name))
+	bytes.buffer_write_string(&buf, index_name)
+
+	return bytes.buffer_to_bytes(&buf)
+}
+
+// Build GSI partition prefix for querying within a single partition:
+//   [gsi][table_name][index_name][pk_value]
+build_gsi_partition_prefix :: proc(table_name: string, index_name: string, pk_value: []byte) -> []byte {
+	buf: bytes.Buffer
+	bytes.buffer_init_allocator(&buf, 0, 512, context.allocator)
+
+	bytes.buffer_write_byte(&buf, u8(Entity_Type.GSI))
+
+	encode_varint(&buf, len(table_name))
+	bytes.buffer_write_string(&buf, table_name)
+
+	encode_varint(&buf, len(index_name))
+	bytes.buffer_write_string(&buf, index_name)
+
+	encode_varint(&buf, len(pk_value))
+	bytes.buffer_write(&buf, pk_value)
+
+	return bytes.buffer_to_bytes(&buf)
+}
+
+// Decode a GSI key back into components
+Decoded_GSI_Key :: struct {
+	table_name: string,
+	index_name: string,
+	pk_value:   []byte,
+	sk_value:   Maybe([]byte),
+}
+
+decode_gsi_key :: proc(key: []byte) -> (result: Decoded_GSI_Key, ok: bool) {
+	decoder := Key_Decoder{data = key, pos = 0}
+
+	entity_type := decoder_read_entity_type(&decoder) or_return
+	if entity_type != .GSI {
+		return {}, false
+	}
+
+	table_name_bytes := decoder_read_segment(&decoder) or_return
+	result.table_name = string(table_name_bytes)
+
+	index_name_bytes := decoder_read_segment(&decoder) or_return
+	result.index_name = string(index_name_bytes)
+
+	result.pk_value = decoder_read_segment(&decoder) or_return
+
+	if decoder_has_more(&decoder) {
+		sk := decoder_read_segment(&decoder) or_return
+		result.sk_value = sk
+	}
+
+	return result, true
+}
+
+// Build GSI prefix for deleting all GSI entries for a table (used by delete_table)
+//   [gsi][table_name]
+build_gsi_table_prefix :: proc(table_name: string) -> []byte {
+	buf: bytes.Buffer
+	bytes.buffer_init_allocator(&buf, 0, 256, context.allocator)
+
+	bytes.buffer_write_byte(&buf, u8(Entity_Type.GSI))
+
+	encode_varint(&buf, len(table_name))
+	bytes.buffer_write_string(&buf, table_name)
+
+	return bytes.buffer_to_bytes(&buf)
+}

dynamodb/storage.odin

@@ -84,7 +84,23 @@ table_metadata_destroy :: proc(metadata: ^Table_Metadata, allocator: mem.Allocat
 	}
 	delete(metadata.attribute_definitions, allocator)
 
-	// TODO: Free GSI/LSI if we implement them
+	// Free GSI definitions
+	if gsis, has_gsis := metadata.global_secondary_indexes.?; has_gsis {
+		for gsi in gsis {
+			delete(gsi.index_name, allocator)
+			for ks in gsi.key_schema {
+				delete(ks.attribute_name, allocator)
+			}
+			delete(gsi.key_schema, allocator)
+			if nka, has_nka := gsi.projection.non_key_attributes.?; has_nka {
+				for attr in nka {
+					delete(attr, allocator)
+				}
+				delete(nka, allocator)
+			}
+		}
+		delete(gsis, allocator)
+	}
 }
 
 // Get the partition key attribute name
@@ -187,7 +203,6 @@ remove_table_lock :: proc(engine: ^Storage_Engine, table_name: string) {
 
 // Serialize table metadata to binary format
 serialize_table_metadata :: proc(metadata: ^Table_Metadata) -> ([]byte, bool) {
-	// Create a temporary item to hold metadata
 	meta_item := make(Item, context.temp_allocator)
 	defer delete(meta_item)
 
@@ -200,7 +215,7 @@ serialize_table_metadata :: proc(metadata: ^Table_Metadata) -> ([]byte, bool) {
 		if i > 0 {
 			strings.write_string(&ks_builder, ",")
 		}
-		fmt.sbprintf(&ks_builder, `{"AttributeName":"%s","KeyType":"%s"}`,
+		fmt.sbprintf(&ks_builder, `{{"AttributeName":"%s","KeyType":"%s"}}`,
 			ks.attribute_name, key_type_to_string(ks.key_type))
 	}
 	strings.write_string(&ks_builder, "]")
@@ -216,7 +231,7 @@ serialize_table_metadata :: proc(metadata: ^Table_Metadata) -> ([]byte, bool) {
 		if i > 0 {
 			strings.write_string(&ad_builder, ",")
 		}
-		fmt.sbprintf(&ad_builder, `{"AttributeName":"%s","AttributeType":"%s"}`,
+		fmt.sbprintf(&ad_builder, `{{"AttributeName":"%s","AttributeType":"%s"}}`,
 			ad.attribute_name, scalar_type_to_string(ad.attribute_type))
 	}
 	strings.write_string(&ad_builder, "]")
@@ -227,6 +242,48 @@ serialize_table_metadata :: proc(metadata: ^Table_Metadata) -> ([]byte, bool) {
 	meta_item["TableStatus"] = String(strings.clone(table_status_to_string(metadata.table_status)))
 	meta_item["CreationDateTime"] = Number(fmt.aprint(metadata.creation_date_time))
 
+	// Encode GSI definitions as JSON string
+	if gsis, has_gsis := metadata.global_secondary_indexes.?; has_gsis && len(gsis) > 0 {
+		gsi_builder := strings.builder_make(context.temp_allocator)
+		defer strings.builder_destroy(&gsi_builder)
+
+		strings.write_string(&gsi_builder, "[")
+		for gsi, i in gsis {
+			if i > 0 {
+				strings.write_string(&gsi_builder, ",")
+			}
+			fmt.sbprintf(&gsi_builder, `{{"IndexName":"%s","KeySchema":[`, gsi.index_name)
+			for ks, j in gsi.key_schema {
+				if j > 0 {
+					strings.write_string(&gsi_builder, ",")
+				}
+				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":"`)
+			switch gsi.projection.projection_type {
+			case .ALL:       strings.write_string(&gsi_builder, "ALL")
+			case .KEYS_ONLY: strings.write_string(&gsi_builder, "KEYS_ONLY")
+			case .INCLUDE:   strings.write_string(&gsi_builder, "INCLUDE")
+			}
+			strings.write_string(&gsi_builder, `"`)
+			if nka, has_nka := gsi.projection.non_key_attributes.?; has_nka && len(nka) > 0 {
+				strings.write_string(&gsi_builder, `,"NonKeyAttributes":[`)
+				for attr, k in nka {
+					if k > 0 {
+						strings.write_string(&gsi_builder, ",")
+					}
+					fmt.sbprintf(&gsi_builder, `"%s"`, attr)
+				}
+				strings.write_string(&gsi_builder, "]")
+			}
+			strings.write_string(&gsi_builder, "}}")
+		}
+		strings.write_string(&gsi_builder, "]")
+
+		meta_item["GlobalSecondaryIndexes"] = String(strings.clone(strings.to_string(gsi_builder)))
+	}
+
 	// Encode to binary
 	return encode(meta_item)
 }
@@ -282,6 +339,17 @@ deserialize_table_metadata :: proc(data: []byte, allocator: mem.Allocator) -> (T
 		}
 	}
 
+	// Parse GlobalSecondaryIndexes from embedded JSON string
+	if gsi_val, gsi_found := meta_item["GlobalSecondaryIndexes"]; gsi_found {
+		#partial switch v in gsi_val {
+		case String:
+			gsis, gsi_ok := parse_gsis_json(string(v), allocator)
+			if gsi_ok && len(gsis) > 0 {
+				metadata.global_secondary_indexes = gsis
+			}
+		}
+	}
+
 	return metadata, true
 }
 
@@ -463,6 +531,7 @@ create_table :: proc(
 	table_name: string,
 	key_schema: []Key_Schema_Element,
 	attribute_definitions: []Attribute_Definition,
+	gsis: Maybe([]Global_Secondary_Index) = nil,
 ) -> (Table_Description, Storage_Error) {
 	table_lock := get_or_create_table_lock(engine, table_name)
 	sync.rw_mutex_lock(table_lock)
@@ -500,6 +569,34 @@ create_table :: proc(
 		ad.attribute_name = strings.clone(ad.attribute_name, engine.allocator)
 	}
 
+	// Deep copy GSI definitions into engine allocator
+	if gsi_defs, has_gsis := gsis.?; has_gsis && len(gsi_defs) > 0 {
+		owned_gsis := make([]Global_Secondary_Index, len(gsi_defs), engine.allocator)
+		for gsi_def, i in gsi_defs {
+			owned_gsis[i] = Global_Secondary_Index{
+				index_name = strings.clone(gsi_def.index_name, engine.allocator),
+				key_schema = make([]Key_Schema_Element, len(gsi_def.key_schema), engine.allocator),
+				projection = Projection{
+					projection_type = gsi_def.projection.projection_type,
+				},
+			}
+			for ks, j in gsi_def.key_schema {
+				owned_gsis[i].key_schema[j] = Key_Schema_Element{
+					attribute_name = strings.clone(ks.attribute_name, engine.allocator),
+					key_type = ks.key_type,
+				}
+			}
+			if nka, has_nka := gsi_def.projection.non_key_attributes.?; has_nka {
+				owned_nka := make([]string, len(nka), engine.allocator)
+				for attr, k in nka {
+					owned_nka[k] = strings.clone(attr, engine.allocator)
+				}
+				owned_gsis[i].projection.non_key_attributes = owned_nka
+			}
+		}
+		metadata.global_secondary_indexes = owned_gsis
+	}
+
 	// Serialize and store
 	meta_value, serialize_ok := serialize_table_metadata(&metadata)
 	if !serialize_ok {
@@ -522,6 +619,7 @@ create_table :: proc(
 		creation_date_time = now,
 		item_count = 0,
 		table_size_bytes = 0,
+		global_secondary_indexes = gsis,
 	}
 
 	return desc, .None
@@ -565,7 +663,6 @@ delete_table :: proc(engine: ^Storage_Engine, table_name: string) -> Storage_Err
 				break
 			}
 
-			// Delete this item
 			err: cstring
 			rocksdb.rocksdb_delete(
 				engine.db.handle,
@@ -582,6 +679,41 @@ delete_table :: proc(engine: ^Storage_Engine, table_name: string) -> Storage_Err
 		}
 	}
 
+	// Delete all GSI entries for this table
+	gsi_table_prefix := build_gsi_table_prefix(table_name)
+	defer delete(gsi_table_prefix)
+
+	gsi_iter := rocksdb.rocksdb_create_iterator(engine.db.handle, engine.db.read_options)
+	if gsi_iter != nil {
+		defer rocksdb.rocksdb_iter_destroy(gsi_iter)
+
+		rocksdb.rocksdb_iter_seek(gsi_iter, raw_data(gsi_table_prefix), c.size_t(len(gsi_table_prefix)))
+
+		for rocksdb.rocksdb_iter_valid(gsi_iter) != 0 {
+			key_len: c.size_t
+			key_ptr := rocksdb.rocksdb_iter_key(gsi_iter, &key_len)
+			key_bytes := key_ptr[:key_len]
+
+			if !has_prefix(key_bytes, gsi_table_prefix) {
+				break
+			}
+
+			err: cstring
+			rocksdb.rocksdb_delete(
+				engine.db.handle,
+				engine.db.write_options,
+				raw_data(key_bytes),
+				c.size_t(len(key_bytes)),
+				&err,
+			)
+			if err != nil {
+				rocksdb.rocksdb_free(rawptr(err))
+			}
+
+			rocksdb.rocksdb_iter_next(gsi_iter)
+		}
+	}
+
 	// Delete metadata
 	del_err := rocksdb.db_delete(&engine.db, meta_key)
 	if del_err != .None {
@@ -639,6 +771,17 @@ 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 ---
+	existing_value, existing_err := rocksdb.db_get(&engine.db, storage_key)
+	if existing_err == .None && 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)
+		}
+	}
+
 	// Encode item
 	encoded_item, encode_ok := encode(item)
 	if !encode_ok {
@@ -652,6 +795,12 @@ put_item :: proc(engine: ^Storage_Engine, table_name: string, item: Item) -> Sto
 		return .RocksDB_Error
 	}
 
+	// --- GSI maintenance: write NEW GSI entries ---
+	gsi_err := gsi_write_entries(engine, table_name, item, &metadata)
+	if gsi_err != .None {
+		return gsi_err
+	}
+
 	return .None
 }
 
@@ -748,6 +897,17 @@ 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 ---
+	existing_value, existing_err := rocksdb.db_get(&engine.db, storage_key)
+	if existing_err == .None && 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)
+		}
+	}
+
 	// Delete from RocksDB
 	del_err := rocksdb.db_delete(&engine.db, storage_key)
 	if del_err != .None {

dynamodb/update_item.odin

@@ -120,6 +120,12 @@ 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

@@ -0,0 +1,276 @@
+// gsi_handlers.odin — GSI-related HTTP handler helpers
+//
+// This file lives in the main package alongside main.odin.
+// It provides:
+//   1. parse_global_secondary_indexes — parse GSI definitions from CreateTable request
+//   2. parse_index_name              — extract IndexName from Query/Scan requests
+//   3. Projection type helper for response building
+package main
+
+import "core:encoding/json"
+import "core:strings"
+import "dynamodb"
+
+// ============================================================================
+// Parse GlobalSecondaryIndexes from CreateTable request body
+//
+// DynamoDB CreateTable request format for GSIs:
+// {
+//   "GlobalSecondaryIndexes": [
+//     {
+//       "IndexName": "email-index",
+//       "KeySchema": [
+//         { "AttributeName": "email", "KeyType": "HASH" },
+//         { "AttributeName": "timestamp", "KeyType": "RANGE" }
+//       ],
+//       "Projection": {
+//         "ProjectionType": "ALL" | "KEYS_ONLY" | "INCLUDE",
+//         "NonKeyAttributes": ["attr1", "attr2"]  // only for INCLUDE
+//       }
+//     }
+//   ]
+// }
+//
+// Returns nil if no GSI definitions are present (valid — GSIs are optional).
+// ============================================================================
+
+parse_global_secondary_indexes :: proc(
+	root: json.Object,
+	attr_defs: []dynamodb.Attribute_Definition,
+) -> Maybe([]dynamodb.Global_Secondary_Index) {
+	gsi_val, found := root["GlobalSecondaryIndexes"]
+	if !found {
+		return nil
+	}
+
+	gsi_arr, ok := gsi_val.(json.Array)
+	if !ok || len(gsi_arr) == 0 {
+		return nil
+	}
+
+	gsis := make([]dynamodb.Global_Secondary_Index, len(gsi_arr))
+
+	for elem, i in gsi_arr {
+		elem_obj, elem_ok := elem.(json.Object)
+		if !elem_ok {
+			cleanup_parsed_gsis(gsis[:i])
+			delete(gsis)
+			return nil
+		}
+
+		gsi, gsi_ok := parse_single_gsi(elem_obj, attr_defs)
+		if !gsi_ok {
+			cleanup_parsed_gsis(gsis[:i])
+			delete(gsis)
+			return nil
+		}
+
+		gsis[i] = gsi
+	}
+
+	return gsis
+}
+
+@(private = "file")
+parse_single_gsi :: proc(
+	obj: json.Object,
+	attr_defs: []dynamodb.Attribute_Definition,
+) -> (dynamodb.Global_Secondary_Index, bool) {
+	gsi: dynamodb.Global_Secondary_Index
+
+	// IndexName (required)
+	idx_val, idx_found := obj["IndexName"]
+	if !idx_found {
+		return {}, false
+	}
+	idx_str, idx_ok := idx_val.(json.String)
+	if !idx_ok {
+		return {}, false
+	}
+	gsi.index_name = strings.clone(string(idx_str))
+
+	// KeySchema (required)
+	ks_val, ks_found := obj["KeySchema"]
+	if !ks_found {
+		delete(gsi.index_name)
+		return {}, false
+	}
+	ks_arr, ks_ok := ks_val.(json.Array)
+	if !ks_ok || len(ks_arr) == 0 || len(ks_arr) > 2 {
+		delete(gsi.index_name)
+		return {}, false
+	}
+
+	key_schema := make([]dynamodb.Key_Schema_Element, len(ks_arr))
+	hash_count := 0
+
+	for ks_elem, j in ks_arr {
+		ks_obj, kobj_ok := ks_elem.(json.Object)
+		if !kobj_ok {
+			for k in 0..<j { delete(key_schema[k].attribute_name) }
+			delete(key_schema)
+			delete(gsi.index_name)
+			return {}, false
+		}
+
+		an_val, an_found := ks_obj["AttributeName"]
+		if !an_found {
+			for k in 0..<j { delete(key_schema[k].attribute_name) }
+			delete(key_schema)
+			delete(gsi.index_name)
+			return {}, false
+		}
+		an_str, an_ok := an_val.(json.String)
+		if !an_ok {
+			for k in 0..<j { delete(key_schema[k].attribute_name) }
+			delete(key_schema)
+			delete(gsi.index_name)
+			return {}, false
+		}
+
+		kt_val, kt_found := ks_obj["KeyType"]
+		if !kt_found {
+			for k in 0..<j { delete(key_schema[k].attribute_name) }
+			delete(key_schema)
+			delete(gsi.index_name)
+			return {}, false
+		}
+		kt_str, kt_ok := kt_val.(json.String)
+		if !kt_ok {
+			for k in 0..<j { delete(key_schema[k].attribute_name) }
+			delete(key_schema)
+			delete(gsi.index_name)
+			return {}, false
+		}
+
+		kt, kt_parse_ok := dynamodb.key_type_from_string(string(kt_str))
+		if !kt_parse_ok {
+			for k in 0..<j { delete(key_schema[k].attribute_name) }
+			delete(key_schema)
+			delete(gsi.index_name)
+			return {}, false
+		}
+
+		if kt == .HASH {
+			hash_count += 1
+		}
+
+		// Validate that the GSI key attribute is in AttributeDefinitions
+		attr_defined := false
+		for ad in attr_defs {
+			if ad.attribute_name == string(an_str) {
+				attr_defined = true
+				break
+			}
+		}
+		if !attr_defined {
+			for k in 0..<j { delete(key_schema[k].attribute_name) }
+			delete(key_schema)
+			delete(gsi.index_name)
+			return {}, false
+		}
+
+		key_schema[j] = dynamodb.Key_Schema_Element{
+			attribute_name = strings.clone(string(an_str)),
+			key_type = kt,
+		}
+	}
+
+	// Must have exactly one HASH key
+	if hash_count != 1 {
+		for ks in key_schema { delete(ks.attribute_name) }
+		delete(key_schema)
+		delete(gsi.index_name)
+		return {}, false
+	}
+
+	gsi.key_schema = key_schema
+
+	// Projection (optional — defaults to ALL)
+	gsi.projection.projection_type = .ALL
+	if proj_val, proj_found := obj["Projection"]; proj_found {
+		if proj_obj, proj_ok := proj_val.(json.Object); proj_ok {
+			if pt_val, pt_found := proj_obj["ProjectionType"]; pt_found {
+				if pt_str, pt_ok := pt_val.(json.String); pt_ok {
+					switch string(pt_str) {
+					case "ALL":       gsi.projection.projection_type = .ALL
+					case "KEYS_ONLY": gsi.projection.projection_type = .KEYS_ONLY
+					case "INCLUDE":   gsi.projection.projection_type = .INCLUDE
+					}
+				}
+			}
+
+			// NonKeyAttributes (only valid for INCLUDE projection)
+			if nka_val, nka_found := proj_obj["NonKeyAttributes"]; nka_found {
+				if nka_arr, nka_ok := nka_val.(json.Array); nka_ok && len(nka_arr) > 0 {
+					nka := make([]string, len(nka_arr))
+					for attr_val, k in nka_arr {
+						if attr_str, attr_ok := attr_val.(json.String); attr_ok {
+							nka[k] = strings.clone(string(attr_str))
+						}
+					}
+					gsi.projection.non_key_attributes = nka
+				}
+			}
+		}
+	}
+
+	return gsi, true
+}
+
+@(private = "file")
+cleanup_parsed_gsis :: proc(gsis: []dynamodb.Global_Secondary_Index) {
+	for gsi in gsis {
+		delete(gsi.index_name)
+		for ks in gsi.key_schema {
+			delete(ks.attribute_name)
+		}
+		delete(gsi.key_schema)
+		if nka, has_nka := gsi.projection.non_key_attributes.?; has_nka {
+			for attr in nka { delete(attr) }
+			delete(nka)
+		}
+	}
+}
+
+// ============================================================================
+// Parse IndexName from Query/Scan request
+// ============================================================================
+
+parse_index_name :: proc(request_body: []byte) -> Maybe(string) {
+	data, parse_err := json.parse(request_body, allocator = context.temp_allocator)
+	if parse_err != nil {
+		return nil
+	}
+	defer json.destroy_value(data)
+
+	root, root_ok := data.(json.Object)
+	if !root_ok {
+		return nil
+	}
+
+	idx_val, found := root["IndexName"]
+	if !found {
+		return nil
+	}
+
+	idx_str, ok := idx_val.(json.String)
+	if !ok {
+		return nil
+	}
+
+	return string(idx_str)
+}
+
+// ============================================================================
+// Projection type to string for DescribeTable response
+// ============================================================================
+
+projection_type_to_string :: proc(pt: dynamodb.Projection_Type) -> string {
+	switch pt {
+	case .ALL:       return "ALL"
+	case .KEYS_ONLY: return "KEYS_ONLY"
+	case .INCLUDE:   return "INCLUDE"
+	}
+	return "ALL"
+}

main.odin

@@ -173,8 +173,25 @@ handle_create_table :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Req
 		return
 	}
 
+	// Parse GlobalSecondaryIndexes (optional)
+	gsis := parse_global_secondary_indexes(root, attr_defs)
+	defer {
+		if gsi_list, has := gsis.?; has {
+			for &g in gsi_list {
+				delete(g.index_name)
+				for &ks in g.key_schema { delete(ks.attribute_name) }
+				delete(g.key_schema)
+				if nka, has_nka := g.projection.non_key_attributes.?; has_nka {
+					for a in nka { delete(a) }
+					delete(nka)
+				}
+			}
+			delete(gsi_list)
+		}
+	}
+
 	// Create the table
-	desc, create_err := dynamodb.create_table(engine, string(table_name), key_schema, attr_defs)
+	desc, create_err := dynamodb.create_table(engine, string(table_name), key_schema, attr_defs, gsis)
 	if create_err != .None {
 		#partial switch create_err {
 		case .Table_Already_Exists:
@@ -261,7 +278,30 @@ handle_describe_table :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_R
 			ad.attribute_name, dynamodb.scalar_type_to_string(ad.attribute_type))
 	}
 
-	strings.write_string(&builder, `]}}`)
+	strings.write_string(&builder, `]`)
+
+	// Include GSI Info — INSIDE the Table object, before the closing braces
+	if gsis, has_gsis := metadata.global_secondary_indexes.?; has_gsis && len(gsis) > 0 {
+		strings.write_string(&builder, `,"GlobalSecondaryIndexes":[`)
+		for gsi, gi in gsis {
+			if gi > 0 do strings.write_string(&builder, ",")
+			strings.write_string(&builder, `{"IndexName":"`)
+			strings.write_string(&builder, gsi.index_name)
+			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, `],"Projection":{"ProjectionType":"`)
+			strings.write_string(&builder, projection_type_to_string(gsi.projection.projection_type))
+			strings.write_string(&builder, `"},"IndexStatus":"ACTIVE"}`)
+		}
+		strings.write_string(&builder, "]")
+	}
+
+	// Close Table object and root object
+	strings.write_string(&builder, `}}`)
 
 	resp_body := strings.to_string(builder)
 	response_set_body(response, transmute([]byte)resp_body)
@@ -1054,6 +1094,9 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 		return
 	}
 
+	// Grab index name from request body
+	index_name := parse_index_name(request.body)
+
 	// Fetch table metadata early for ExclusiveStartKey parsing
 	metadata, meta_err := dynamodb.get_table_metadata(engine, table_name)
 	if meta_err != .None {
@@ -1081,6 +1124,8 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 	copy(pk_owned, pk_bytes)
 	defer delete(pk_owned)
 
+	// ---- Parse shared parameters BEFORE the GSI/table branch ----
+
 	// Parse Limit
 	limit := dynamodb.parse_limit(request.body)
 	if limit == 0 {
@@ -1107,13 +1152,6 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 		sk_condition = skc
 	}
 
-	result, err := dynamodb.query(engine, table_name, pk_owned, exclusive_start_key, limit, sk_condition)
-	if err != .None {
-		handle_storage_error(response, err)
-		return
-	}
-	defer dynamodb.query_result_destroy(&result)
-
 	// ---- Parse ExpressionAttributeNames/Values for filter/projection ----
 	attr_names := dynamodb.parse_expression_attribute_names(request.body)
 	defer {
@@ -1137,6 +1175,62 @@ handle_query :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, r
 		delete(attr_values)
 	}
 
+	// ---- GSI query path ----
+	if idx_name, has_idx := index_name.?; has_idx {
+		_, 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_query(engine, table_name, idx_name,
+			pk_owned, exclusive_start_key, limit, sk_condition)
+		if err != .None {
+			handle_storage_error(response, err)
+			return
+		}
+		defer dynamodb.query_result_destroy(&result)
+
+		// Apply FilterExpression
+		filtered_items := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
+		scanned_count := len(result.items)
+
+		// Apply ProjectionExpression
+		projection, has_proj := dynamodb.parse_projection_expression(request.body, attr_names)
+		final_items: []dynamodb.Item
+
+		if has_proj && len(projection) > 0 {
+			projected := make([]dynamodb.Item, len(filtered_items))
+			for item, i in filtered_items {
+				projected[i] = dynamodb.apply_projection(item, projection)
+			}
+			final_items = projected
+		} else {
+			final_items = filtered_items
+		}
+
+		write_items_response_with_pagination_ex(
+			response, final_items, result.last_evaluated_key, &metadata, scanned_count,
+		)
+
+		if has_proj && len(projection) > 0 {
+			for &item in final_items {
+				dynamodb.item_destroy(&item)
+			}
+			delete(final_items)
+		}
+		return
+	}
+
+	// ---- Main table query path ----
+	result, err := dynamodb.query(engine, table_name, pk_owned, exclusive_start_key, limit, sk_condition)
+	if err != .None {
+		handle_storage_error(response, err)
+		return
+	}
+	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)
 	scanned_count := len(result.items)
@@ -1177,6 +1271,9 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 		return
 	}
 
+	// Grab index name from request body
+	index_name := parse_index_name(request.body)
+
 	metadata, meta_err := dynamodb.get_table_metadata(engine, table_name)
 	if meta_err != .None {
 		handle_storage_error(response, meta_err)
@@ -1202,13 +1299,6 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 		}
 	}
 
-	result, err := dynamodb.scan(engine, table_name, exclusive_start_key, limit)
-	if err != .None {
-		handle_storage_error(response, err)
-		return
-	}
-	defer dynamodb.scan_result_destroy(&result)
-
 	// ---- Parse ExpressionAttributeNames/Values for filter/projection ----
 	attr_names := dynamodb.parse_expression_attribute_names(request.body)
 	defer {
@@ -1232,6 +1322,59 @@ handle_scan :: proc(engine: ^dynamodb.Storage_Engine, request: ^HTTP_Request, re
 		delete(attr_values)
 	}
 
+	// ---- GSI scan path ----
+	if idx_name, has_idx := index_name.?; has_idx {
+		_, 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)
+		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)
+		scanned_count := len(result.items)
+
+		projection, has_proj := dynamodb.parse_projection_expression(request.body, attr_names)
+		final_items: []dynamodb.Item
+
+		if has_proj && len(projection) > 0 {
+			projected := make([]dynamodb.Item, len(filtered_items))
+			for item, i in filtered_items {
+				projected[i] = dynamodb.apply_projection(item, projection)
+			}
+			final_items = projected
+		} else {
+			final_items = filtered_items
+		}
+
+		write_items_response_with_pagination_ex(
+			response, final_items, result.last_evaluated_key, &metadata, scanned_count,
+		)
+
+		if has_proj && len(projection) > 0 {
+			for &item in final_items {
+				dynamodb.item_destroy(&item)
+			}
+			delete(final_items)
+		}
+		return
+	}
+
+	// ---- Main table scan path ----
+	result, err := dynamodb.scan(engine, table_name, exclusive_start_key, limit)
+	if err != .None {
+		handle_storage_error(response, err)
+		return
+	}
+	defer dynamodb.scan_result_destroy(&result)
+
 	// ---- Apply FilterExpression ----
 	filtered_items := apply_filter_to_items(request.body, result.items, attr_names, attr_values)
 	scanned_count := len(result.items)