UNLOCK STATS

UNLOCK STATS 语句用于解锁统计信息被锁定的表。

语法图

UnlockStatsStmt

UNLOCK STATS - 图1

TableNameList

UNLOCK STATS - 图2

TableName

UNLOCK STATS - 图3

PartitionNameList

UNLOCK STATS - 图4

1. UnlockStatsStmt ::=
2. 'UNLOCK' 'STATS' (TableNameList) | (TableName 'PARTITION' PartitionNameList)

4. TableNameList ::=
5. TableName (',' TableName)*

7. TableName ::=
8. Identifier ( '.' Identifier )?

10. PartitionNameList ::=
11. Identifier ( ',' Identifier )*

示例

参考 LOCK STATS 语句的示例来创建表 t，并锁定表 t 的统计信息。

解锁表 t 的统计信息，成功执行 ANALYZE 语句。

1. mysql> UNLOCK STATS t;
2. Query OK, 0 rows affected (0.01 sec)

4. mysql> ANALYZE TABLE t;
5. Query OK, 0 rows affected, 1 warning (0.03 sec)

7. mysql> SHOW WARNINGS;
8. +-------+------+-----------------------------------------------------------------------------------------------------------------------------------------+
9. | Level | Code | Message                                                                                                                                 |
10. +-------+------+-----------------------------------------------------------------------------------------------------------------------------------------+
11. | Note  | 1105 | Analyze use auto adjusted sample rate 1.000000 for table test.t, reason to use this rate is "use min(1, 110000/8) as the sample-rate=1" |
12. +-------+------+-----------------------------------------------------------------------------------------------------------------------------------------+
13. 1 row in set (0.00 sec)

参考 LOCK STATS 语句的示例来创建表 t，并锁定表 t 的分区 p1 的统计信息。

解锁分区 p1 的统计信息，成功执行 ANALYZE 语句。

1. mysql> UNLOCK STATS t PARTITION p1;
2. Query OK, 0 rows affected (0.00 sec)

4. mysql> ANALYZE TABLE t PARTITION p1;
5. Query OK, 0 rows affected, 1 warning (0.01 sec)

7. mysql> SHOW WARNINGS;
8. +-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
9. | Level | Code | Message                                                                                                                                                              |
10. +-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
11. | Note  | 1105 | Analyze use auto adjusted sample rate 1.000000 for table test.t's partition p1, reason to use this rate is "TiDB assumes that the table is empty, use sample-rate=1" |
12. +-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
13. 1 row in set (0.00 sec)

MySQL 兼容性

该语句是 TiDB 对 MySQL 语法的扩展。

另请参阅