一条SQL语句的处理过程

RC SessionStage::handle_sql(SQLStageEvent *sql_event)
{RC rc = query_cache_stage_.handle_request(sql_event);if (OB_FAIL(rc)) {LOG_TRACE("failed to do query cache. rc=%s", strrc(rc));return rc;}// SQL语法分析 rc = parse_stage_.handle_request(sql_event);if (OB_FAIL(rc)) {LOG_TRACE("failed to do parse. rc=%s", strrc(rc));return rc;}// SQL语句解析（从语句中解析出相应的参数）rc = resolve_stage_.handle_request(sql_event);if (OB_FAIL(rc)) {LOG_TRACE("failed to do resolve. rc=%s", strrc(rc));return rc;}// SQL优化rc = optimize_stage_.handle_request(sql_event);if (rc != RC::UNIMPLENMENT && rc != RC::SUCCESS) {LOG_TRACE("failed to do optimize. rc=%s", strrc(rc));return rc;}// SQL执行rc = execute_stage_.handle_request(sql_event);if (OB_FAIL(rc)) {LOG_TRACE("failed to do execute. rc=%s", strrc(rc));return rc;}return rc;
}

SQL执行

RC CommandExecutor::execute(SQLStageEvent *sql_event)
{Stmt *stmt = sql_event->stmt();switch (stmt->type()) {case StmtType::CREATE_INDEX: {CreateIndexExecutor executor;return executor.execute(sql_event);} break;case StmtType::CREATE_TABLE: {CreateTableExecutor executor;return executor.execute(sql_event);} break;case StmtType::DESC_TABLE: {DescTableExecutor executor;return executor.execute(sql_event);}case StmtType::HELP: {HelpExecutor executor;return executor.execute(sql_event);}case StmtType::SHOW_TABLES: {ShowTablesExecutor executor;return executor.execute(sql_event);}case StmtType::BEGIN: {TrxBeginExecutor executor;return executor.execute(sql_event);}case StmtType::COMMIT:case StmtType::ROLLBACK: {TrxEndExecutor executor;return executor.execute(sql_event);}case StmtType::SET_VARIABLE: {SetVariableExecutor executor;return executor.execute(sql_event);}case StmtType::LOAD_DATA: {LoadDataExecutor executor;return executor.execute(sql_event);}case StmtType::EXIT: {return RC::SUCCESS;}default: {LOG_ERROR("unknown command: %d", static_cast<int>(stmt->type()));return RC::UNIMPLENMENT;}}return RC::INTERNAL;
}