sql-statement-analyze-table.md

title	summary	category	aliases
ANALYZE TABLE	TiDB 数据库中 ANALYZE TABLE 的使用概况。	reference	/docs-cn/dev/reference/sql/statements/analyze-table/

ANALYZE TABLE

ANALYZE TABLE 语句用于更新 TiDB 在表和索引上留下的统计信息。执行大批量更新或导入记录后，或查询执行计划不是最佳时，建议运行 ANALYZE TABLE。

当 TiDB 逐渐发现这些统计数据与预估不一致时，也会自动更新其统计数据。

语法图

AnalyzeTableStmt:

TableNameList:

TableName:

示例

{{< copyable "sql" >}}

CREATE TABLE t1 (id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, c1 INT NOT NULL);

Query OK, 0 rows affected (0.11 sec)

{{< copyable "sql" >}}

INSERT INTO t1 (c1) VALUES (1),(2),(3),(4),(5);

Query OK, 5 rows affected (0.03 sec)
Records: 5  Duplicates: 0  Warnings: 0

{{< copyable "sql" >}}

ALTER TABLE t1 ADD INDEX (c1);

Query OK, 0 rows affected (0.30 sec)

{{< copyable "sql" >}}

EXPLAIN SELECT * FROM t1 WHERE c1 = 3;

+------------------------+---------+-----------+------------------------+---------------------------------------------+
| id                     | estRows | task      | access object          | operator info                               |
+------------------------+---------+-----------+------------------------+---------------------------------------------+
| IndexReader_6          | 10.00   | root      |                        | index:IndexRangeScan_5                      |
| └─IndexRangeScan_5     | 10.00   | cop[tikv] | table:t1, index:c1(c1) | range:[3,3], keep order:false, stats:pseudo |
+------------------------+---------+-----------+------------------------+---------------------------------------------+
2 rows in set (0.00 sec)

{{< copyable "sql" >}}

analyze table t1;

Query OK, 0 rows affected (0.13 sec)

{{< copyable "sql" >}}

EXPLAIN SELECT * FROM t1 WHERE c1 = 3;

+------------------------+---------+-----------+------------------------+-------------------------------+
| id                     | estRows | task      | access object          | operator info                 |
+------------------------+---------+-----------+------------------------+-------------------------------+
| IndexReader_6          | 1.00    | root      |                        | index:IndexRangeScan_5        |
| └─IndexRangeScan_5     | 1.00    | cop[tikv] | table:t1, index:c1(c1) | range:[3,3], keep order:false |
+------------------------+---------+-----------+------------------------+-------------------------------+
2 rows in set (0.00 sec)

MySQL 兼容性

ANALYZE TABLE 在语法上与 MySQL 类似。但 ANALYZE TABLE 在 TiDB 上执行所需时间可能长得多，因为它的内部运行方式不同。

另请参阅

• EXPLAIN
• EXPLAIN ANALYZE