TRACE 语句用于查看具体 SQL 的执行情况。TRACE [SQL] 和 SHOW TRACE 要结合使用。
注意：TRACE SQL 和 EXPLAIN SQL 的区别在于 TRACE SQL 会实际执行该语句。
例如查看 select 1这条语句的执行情况。
mysql> trace select 1;+---+| 1 |+---+| 1 |+---+1 row in set (0.03 sec)mysql> show trace;+------+----------+----------------+-----------------------------------+---------------+--------------------------+------+-----------+--------+| ID | TYPE | GROUP_NAME | DBKEY_NAME | TIME_COST(MS) | CONNECTION_TIME_COST(MS) | ROWS | STATEMENT | PARAMS |+------+----------+----------------+-----------------------------------+---------------+--------------------------+------+-----------+--------+| 0 | Optimize | DRDS | DRDS | 3 | 0.00 | 0 | select 1 | NULL || 1 | Query | TDDL5_00_GROUP | db218249098_sqa_zmf_tddl5_00_3309 | 7 | 0.15 | 1 | select 1 | NULL |+------+----------+----------------+-----------------------------------+---------------+--------------------------+------+-----------+--------+2 rows in set (0.01 sec)
