global secondary indexes

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)
+}