SHOW STATS_LOCKED

SHOW STATS_LOCKED 语句显示统计信息被锁定的表。

语法图

ShowStatsLockedStmt

ShowLikeOrWhereOpt

1. ShowStatsLockedStmt ::= 'SHOW' 'STATS_LOCKED' ShowLikeOrWhereOpt

3. ShowLikeOrWhereOpt ::= 'LIKE' SimpleExpr | 'WHERE' Expression

示例

创建表 t，插入一些数据，在未锁定表 t 的统计信息的情况下成功执行 ANALYZE 语句。

1. mysql> CREATE TABLE t(a INT, b INT);
2. Query OK, 0 rows affected (0.03 sec)

4. mysql> INSERT INTO t VALUES (1,2), (3,4), (5,6), (7,8);
5. Query OK, 4 rows affected (0.00 sec)
6. Records: 4  Duplicates: 0  Warnings: 0

8. mysql> ANALYZE TABLE t;
9. Query OK, 0 rows affected, 1 warning (0.02 sec)

11. mysql> SHOW WARNINGS;
12. +-------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
13. | Level | Code | Message                                                                                                                                                                                                               |
14. +-------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
15. | Note  | 1105 | Analyze use auto adjusted sample rate 1.000000 for table test.t, reason to use this rate is "Row count in stats_meta is much smaller compared with the row count got by PD, use min(1, 15000/4) as the sample-rate=1" |
16. +-------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
17. 1 row in set (0.00 sec)

锁定表 t 的统计信息，执行 SHOW STATS_LOCKED 语句，显示表 t 的统计信息被锁定。

1. mysql> LOCK STATS t;
2. Query OK, 0 rows affected (0.00 sec)

4. mysql> SHOW STATS_LOCKED;
5. +---------+------------+----------------+--------+
6. | Db_name | Table_name | Partition_name | Status |
7. +---------+------------+----------------+--------+
8. | test    | t          |                | locked |
9. +---------+------------+----------------+--------+
10. 1 row in set (0.01 sec)

MySQL 兼容性

该语句是 TiDB 对 MySQL 语法的扩展。

另请参阅

• 统计信息
• LOCK STATS
• UNLOCK STATS