sqlite: cache column names in stmt.all()

While the statement is running, it is impossible to modify the column
names and thus it is beneficial to create the host-language (JS) keys
once per all rows and reuse them for all results.

With this change the performance of `.all()` improves by around 25%
depending on the number of columns and rows in the result.

PR-URL: #55373
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: Yagiz Nizipli <[email protected]>

src/node_sqlite.cc

@@ -561,23 +561,32 @@ 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;
+ for (size_t i = 0; i < row_keys.size(); ++i) {
  Local<Value> val;
  if (!stmt->ColumnToValue(i).ToLocal(&val)) return;
- row_keys.emplace_back(key);
  row_values.emplace_back(val);
  }
 
- Local<Object> row = Object::New(
- isolate, Null(isolate), row_keys.data(), row_values.data(), num_cols);
+ Local<Object> row = Object::New(isolate,
+ Null(isolate),
+ row_keys.data(),
+ row_values.data(),
+ row_keys.size());
  rows.emplace_back(row);
  }