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13.7.2.1 ANALYZE TABLE Syntax

ANALYZE [NO_WRITE_TO_BINLOG | LOCAL]
    TABLE tbl_name [, tbl_name] ...

ANALYZE TABLE performs a key distribution analysis and stores the distribution for the named table or tables. For MyISAM tables, this statement is equivalent to using myisamchk --analyze.

This statement requires SELECT and INSERT privileges for the table.

ANALYZE TABLE works with InnoDB, NDB, and MyISAM tables. It does not work with views.

ANALYZE TABLE is supported for partitioned tables, and you can use ALTER TABLE ... ANALYZE PARTITION to analyze one or more partitions; for more information, see Section 13.1.7, “ALTER TABLE Syntax”, and Section 19.3.3, “Maintenance of Partitions”.

During the analysis, the table is locked with a read lock for InnoDB and MyISAM.

ANALYZE TABLE removes the table from the table definition cache, which requires a flush lock. If there are long running statements or transactions still using the table, subsequent statements and transactions must wait for those operations to finish before the flush lock is released. Because ANALYZE TABLE itself typically finishes quickly, it may not be apparent that delayed transactions or statements involving the same table are due to the remaining flush lock.

By default, the server writes ANALYZE TABLE statements to the binary log so that they replicate to replication slaves. To suppress logging, specify the optional NO_WRITE_TO_BINLOG keyword or its alias LOCAL.

ANALYZE TABLE Output

ANALYZE TABLE returns a result set with the columns shown in the following table.

Column Value
Table The table name
Op Always analyze
Msg_type status, error, info, note, or warning
Msg_text An informational message
Key Distribution Analysis

If the table has not changed since the last key distribution analysis, the table is not analyzed again.

MySQL uses the stored key distribution to decide the table join order for joins on something other than a constant. In addition, key distributions can be used when deciding which indexes to use for a specific table within a query.

For more information on how key distribution analysis works within InnoDB, see Section 14.11.10, “Configuring Optimizer Statistics for InnoDB”. Also see Section 14.11.10.1, “Estimating ANALYZE TABLE Complexity for InnoDB Tables” and Section 14.9.1.6, “Limits on InnoDB Tables”.

To check the stored key distribution cardinality, use the SHOW INDEX statement or the INFORMATION_SCHEMA STATISTICS table. See Section 13.7.5.23, “SHOW INDEX Syntax”, and Section 21.21, “The INFORMATION_SCHEMA STATISTICS Table”.