sqlite: restore changes from #55373

PR #55373 introduced a performance improvement for the all()
method of prepared statements. Those changes appear to have been
accidentally overwritten in #54181. This change restores the
overwritten code.

Refs: #55373
Refs: #54181
PR-URL: #56908
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>

src/node_sqlite.cc

@@ -1510,18 +1510,22 @@ void StatementSync::All(const FunctionCallbackInfo<Value>& args) {
   auto reset = OnScopeLeave([&]() { sqlite3_reset(stmt->statement_); });
   int num_cols = sqlite3_column_count(stmt->statement_);
   LocalVector<Value> rows(isolate);
+  LocalVector<Name> row_keys(isolate);
   while ((r = sqlite3_step(stmt->statement_)) == SQLITE_ROW) {
-    LocalVector<Name> row_keys(isolate);
-    row_keys.reserve(num_cols);
+    if (row_keys.size() == 0) {
+      row_keys.reserve(num_cols);
+      for (int i = 0; i < num_cols; ++i) {
+        Local<Name> key;
+        if (!stmt->ColumnNameToName(i).ToLocal(&key)) return;
+        row_keys.emplace_back(key);
+      }
+    }
+
     LocalVector<Value> row_values(isolate);
     row_values.reserve(num_cols);
-
     for (int i = 0; i < num_cols; ++i) {
-      Local<Name> key;
-      if (!stmt->ColumnNameToName(i).ToLocal(&key)) return;
       Local<Value> val;
       if (!stmt->ColumnToValue(i).ToLocal(&val)) return;
-      row_keys.emplace_back(key);
       row_values.emplace_back(val);
     }