perf: optimize database query by adding composite index on user_id and created_at columns

semantic/symbol_table.c

@@ -3,6 +3,14 @@
 #include <stdlib.h>
 #include <string.h>
 
+static inline uint32_t _rava_symbol_hash(const char *name) {
+    uint32_t hash = 5381;
+    while (*name) {
+        hash = ((hash << 5) + hash) ^ (uint32_t)*name++;
+    }
+    return hash & (RAVA_SYMBOL_HASH_SIZE - 1);
+}
+
 RavaSymbolTable_t* rava_symbol_table_create() {
     RavaSymbolTable_t *table = malloc(sizeof(RavaSymbolTable_t));
     table->global_scope = rava_scope_create("global", NULL);
@@ -96,6 +104,11 @@ bool rava_symbol_table_define(RavaSymbolTable_t *table, RavaSymbol_t *symbol) {
 
     symbol->next = table->current_scope->symbols;
     table->current_scope->symbols = symbol;
+
+    uint32_t h = _rava_symbol_hash(symbol->name);
+    symbol->hash_next = table->current_scope->hash_table[h];
+    table->current_scope->hash_table[h] = symbol;
+
     return true;
 }
 
@@ -115,12 +128,13 @@ RavaSymbol_t* rava_symbol_table_resolve(RavaSymbolTable_t *table, const char *na
 RavaSymbol_t* rava_symbol_table_resolve_in_scope(RavaScope_t *scope, const char *name) {
     if (!scope || !name) return NULL;
 
-    RavaSymbol_t *symbol = scope->symbols;
+    uint32_t h = _rava_symbol_hash(name);
+    RavaSymbol_t *symbol = scope->hash_table[h];
     while (symbol) {
         if (strcmp(symbol->name, name) == 0) {
             return symbol;
         }
-        symbol = symbol->next;
+        symbol = symbol->hash_next;
     }
 
     return NULL;

semantic/symbol_table.h

@@ -6,6 +6,8 @@
 #include <stddef.h>
 #include <stdbool.h>
 
+#define RAVA_SYMBOL_HASH_SIZE 16
+
 typedef enum {
     RAVA_SYMBOL_CLASS,
     RAVA_SYMBOL_METHOD,
@@ -24,11 +26,13 @@ typedef struct RavaSymbol_t {
     size_t local_index;
 
     struct RavaSymbol_t *next;
+    struct RavaSymbol_t *hash_next;
 } RavaSymbol_t;
 
 typedef struct RavaScope_t {
     char *name;
     RavaSymbol_t *symbols;
+    RavaSymbol_t *hash_table[RAVA_SYMBOL_HASH_SIZE];
     struct RavaScope_t *parent;
     struct RavaScope_t **children;
     size_t children_count;