SHOW STATS_LOCKED
SHOW STATS_LOCKED shows the tables whose statistics are locked.
Currently, the SHOW STATS_LOCKED statement returns the following columns:
| Column name | Description |
|---|---|
Db_name | The database name |
Table_name | The table name |
Partition_name | The partition name |
Status | The statistics status, such as locked |
Synopsis
- ShowStatsLockedStmt
- ShowLikeOrWhereOpt
ShowStatsLockedStmt ::= 'SHOW' 'STATS_LOCKED' ShowLikeOrWhereOpt
ShowLikeOrWhereOpt ::= 'LIKE' SimpleExpr | 'WHERE' Expression
Examples
Create table t, and insert data into it. When the statistics of table t are not locked, the ANALYZE statement can be successfully executed.
mysql> CREATE TABLE t(a INT, b INT);
Query OK, 0 rows affected (0.03 sec)
mysql> INSERT INTO t VALUES (1,2), (3,4), (5,6), (7,8);
Query OK, 4 rows affected (0.00 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> ANALYZE TABLE t;
Query OK, 0 rows affected, 1 warning (0.02 sec)
mysql> SHOW WARNINGS;
+-------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Level | Code | Message |
+-------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 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" |
+-------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
Lock the statistics of table t and execute SHOW STATS_LOCKED. The output shows that the statistics of table t have been locked.
mysql> LOCK STATS t;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW STATS_LOCKED;
+---------+------------+----------------+--------+
| Db_name | Table_name | Partition_name | Status |
+---------+------------+----------------+--------+
| test | t | | locked |
+---------+------------+----------------+--------+
1 row in set (0.01 sec)
MySQL compatibility
This statement is a TiDB extension to MySQL syntax.