SHOW STATS_LOCKED

SHOW STATS_LOCKED 语句显示统计信息被锁定的表。

语法图

ShowStatsLockedStmt

SHOW STATS_LOCKED - 图1

ShowLikeOrWhereOpt

SHOW STATS_LOCKED - 图2

  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