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Крайне быстро они делаются, если отключить опцию innodb_stats_on_metadata

Выдержка из официальной документации:

Version Introduced 5.1.17
Command-Line Format --innodb_stats_on_metadata
Option-File Format innodb_stats_on_metadata
Option Sets Variable Yes, innodb_stats_on_metadata
Variable Name innodb_stats_on_metadata
Variable Scope Global
Dynamic Variable Yes
Permitted Values
Type boolean
Default ON


When this variable is enabled (which is the default, as before
the variable was created), InnoDB updates
statistics during metadata statements such as
SHOW TABLE STATUS or
SHOW INDEX, or when accessing
the INFORMATION_SCHEMA tables
TABLES or
STATISTICS. (These updates are
similar to what happens for ANALYZE
TABLE.) When disabled, InnoDB
does not updates statistics during these operations. Disabling
this variable can improve access speed for schemas that have a
large number of tables or indexes. It can also improve the
stability of execution plans for queries that involve
InnoDB tables.



This variable was added in MySQL 5.1.17.



@темы: MySQL, INFORMATION_SCHEMA