| title | summary | category |
|---|---|---|
ANALYZE TABLE | TiDB SQL Statement Reference |
An overview of the usage of ANALYZE TABLE for the TiDB database. |
reference |
This statement updates the statistics that TiDB builds on tables and indexes. It is recommended to run ANALYZE TABLE after performing a large batch update or import of records, or when you notice that query execution plans are sub-optimal.
TiDB will also automatically update its statistics over time as it discovers that they are inconsistent with its own estimates.
AnalyzeTableStmt:
TableNameList:
TableName:
mysql> CREATE TABLE t1 (id INT NOT NULL PRIMARY KEY auto_increment, c1 INT NOT NULL);
Query OK, 0 rows affected (0.11 sec)
mysql> INSERT INTO t1 (c1) VALUES (1),(2),(3),(4),(5);
Query OK, 5 rows affected (0.03 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> ALTER TABLE t1 ADD INDEX (c1);
Query OK, 0 rows affected (0.30 sec)
mysql> EXPLAIN SELECT * FROM t1 WHERE c1 = 3;
+-------------------+-------+------+-----------------------------------------------------------------+
| id | count | task | operator info |
+-------------------+-------+------+-----------------------------------------------------------------+
| IndexReader_6 | 10.00 | root | index:IndexScan_5 |
| └─IndexScan_5 | 10.00 | cop | table:t1, index:c1, range:[3,3], keep order:false, stats:pseudo |
+-------------------+-------+------+-----------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> analyze table t1;
Query OK, 0 rows affected (0.13 sec)
mysql> EXPLAIN SELECT * FROM t1 WHERE c1 = 3;
+-------------------+-------+------+---------------------------------------------------+
| id | count | task | operator info |
+-------------------+-------+------+---------------------------------------------------+
| IndexReader_6 | 1.00 | root | index:IndexScan_5 |
| └─IndexScan_5 | 1.00 | cop | table:t1, index:c1, range:[3,3], keep order:false |
+-------------------+-------+------+---------------------------------------------------+
2 rows in set (0.00 sec)This statement is syntactically similar with MySQL. However, ANALYZE TABLE may take significantly longer to execute on TiDB, as internally it operates in a different manner.