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OPTIMIZE TABLE Analyzes table, stores the key distribution for a table, reclaims the unused space and defragments the data file. ANALYZE TABLE Only analyzes table and stores the key distribution.

Under normal circumstances you don't need to analyse the table, the index cares for himself, it updates the index and stats automatically. But on high traffic tables, with lots of deletes the index gets "confused" and needs more time to select the right rows, then you run ANALYSE when no other traffic is made.

MySQL ANALYZE TABLE Statement ANALYZE TABLE Statement Without HISTOGRAM. This statement stores the key distribution analysis of the specified table(s). ... ANALYZE TABLE Statement with UPDATE HISTOGRAM. ... ANALYZE TABLE Statement with DROP HISTOGRAM. ... Analyzing multiple tables. ... ANALYZE statement with EXPLAIN.

ANALYZE TABLE causes Oracle to determine how many rows are in the table and how storage is allocated. It also calculates the number of chained rows. The most important pieces of information the optimizer gets from this process are the number of rows and the number of blocks.

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.

The ANALYZE TABLE statement collects statistics about one specific table or all the tables in one specified database, that are to be used by the query optimizer to find a better query execution plan.

When you analyze a table, both table and column statistics are collected. Both computed and estimated statistics are used by the Oracle Database optimizer to choose the execution plan for SQL statements that access analyzed objects.

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

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The way analyze table helps performance is that it updates statistics that the optimizer uses to choose indexes for a given query. If the updated statistics don't make any material difference to the choice of index, it won't have any effect on performance.