work on settings (set and show), perf improvement when adding row into table

usql.cpp

@@ -25,6 +25,8 @@ std::unique_ptr<Table> USql::execute(Node &node) {
 			return execute_create_table(static_cast<CreateTableNode &>(node));
 		case NodeType::create_table_as_select:
 			return execute_create_table_as_table(static_cast<CreateTableAsSelectNode &>(node));
+		case NodeType::drop_table:
+			return execute_drop(static_cast<DropTableNode &>(node));
 		case NodeType::insert_into:
 			return execute_insert_into_table(static_cast<InsertIntoTableNode &>(node));
 		case NodeType::select_from:
@@ -37,8 +39,10 @@ std::unique_ptr<Table> USql::execute(Node &node) {
 			return execute_load(static_cast<LoadIntoTableNode &>(node));
 		case NodeType::save_table:
 			return execute_save(static_cast<SaveTableNode &>(node));
-		case NodeType::drop_table:
-			return execute_drop(static_cast<DropTableNode &>(node));
+		case NodeType::set:
+			return execute_set(static_cast<SetNode &>(node));
+		case NodeType::show:
+			return execute_show(static_cast<ShowNode &>(node));
 		default:
 			return create_stmt_result_table(-1, "unknown statement", 0);
 	}
@@ -68,7 +72,7 @@ std::unique_ptr<Table> USql::execute_create_table_as_table(CreateTableAsSelectNo
 	// must be here, if rows are put into new_table, they are lost during m_tables.push_table
 	Table *table = find_table(node.table_name);
 	for( Row& orig_row : select->m_rows) {
-		table->add_copy_of_row(orig_row);
+		table->commit_copy_of_row(orig_row);
 	}
 
 	select.release();	// is it correct? hoping not to release select table here and then when releasing CreateTableAsSelectNode
@@ -121,6 +125,16 @@ std::unique_ptr<Table> USql::execute_drop(DropTableNode &node) {
 	throw Exception("table not found (" + node.table_name + ")");
 }
 
+std::unique_ptr<Table> USql::execute_set(SetNode &node) {
+	Settings::set_setting(node.name, node.value);
+	return create_stmt_result_table(0, "set succeeded", 1);
+}
+
+std::unique_ptr<Table> USql::execute_show(ShowNode &node) {
+	std::string value = Settings::get_setting(node.name);
+	return create_stmt_result_table(0, "show succeeded: " + value, 1);
+}
+
 std::unique_ptr<Table> USql::execute_insert_into_table(InsertIntoTableNode &node) {
 	// TODO check column names.size = values.size
 
@@ -128,7 +142,7 @@ std::unique_ptr<Table> USql::execute_insert_into_table(InsertIntoTableNode &node
 	Table *table_def = find_table(node.table_name);
 
 	// prepare empty new_row
-	Row new_row = table_def->create_empty_row();
+	Row& new_row = table_def->create_empty_row();
 
 	// copy values
 	for (size_t i = 0; i < node.cols_names.size(); i++) {
@@ -139,7 +153,7 @@ std::unique_ptr<Table> USql::execute_insert_into_table(InsertIntoTableNode &node
 	}
 
 	// append new_row
-	table_def->add_row(new_row);
+	table_def->commit_row(new_row);
 
 	return create_stmt_result_table(0, "insert succeeded", 1);
 }
@@ -175,10 +189,9 @@ std::unique_ptr<Table> USql::execute_select(SelectFromTableNode &node) {
 	for (auto row = begin(table->m_rows); row != end(table->m_rows); ++row) {
 		// eval where for row
 		if (eval_where(node.where.get(), table, *row)) {
-			// prepare empty row
-			Row new_row = result->create_empty_row();
+			// prepare empty row and copy column values
+			Row& new_row = result->create_empty_row();
 
-			// copy column values
 			for (auto idx = 0; idx < result->columns_count(); idx++) {
 				auto row_col_index = source_table_col_index[idx];
 
@@ -194,7 +207,7 @@ std::unique_ptr<Table> USql::execute_select(SelectFromTableNode &node) {
 			}
 
 			// add row to result
-			result->m_rows.push_back(new_row);
+			result->commit_row(new_row);
 		}
 	}
 
@@ -317,7 +330,7 @@ std::unique_ptr<Table> USql::execute_update(UpdateTableNode &node) {
 
 
 bool USql::eval_where(Node *where, Table *table, Row &row) {
-	switch (where->node_type) {    // no where clause
+	switch (where->node_type) {
 		case NodeType::true_node:
 			return true;
 		case NodeType::relational_operator:     //  just one condition
@@ -544,11 +557,11 @@ std::unique_ptr<Table> USql::create_stmt_result_table(long code, const std::stri
 
 	auto table_def = std::make_unique<Table>("result", result_tbl_col_defs);
 
-	Row new_row = table_def->create_empty_row();
+	Row& new_row = table_def->create_empty_row();
 	new_row.setIntColumnValue(0, code);
 	new_row.setStringColumnValue(1, text);
 	new_row.setIntColumnValue(2, affected_rows);
-	table_def->add_row(new_row);
+	table_def->commit_row(new_row);
 
 	return std::move(table_def);
 }