mysql.index_stats Table

MariaDB starting with 10.0.1

The mysql.index_stats table was introduced as part of the Engine-independent table statistics feature implemented in MariaDB 10.0.1.

The mysql.index_stats table is one of three tables storing data used for Engine-independent table statistics added in MariaDB 10.0.1. The others are mysql.column_stats and mysql.table_stats.

MariaDB starting with 10.4

In MariaDB 10.4 and later, this table uses the Aria storage engine.

MariaDB until 10.3

In MariaDB 10.3 and before, this table uses the MyISAM storage engine.

The mysql.index_stats table contains the following fields:

FieldTypeNullKeyDefaultDescription
db_namevarchar(64)NOPRINULLDatabase the table is in.
table_namevarchar(64)NOPRINULLTable name
index_namevarchar(64)NOPRINULLName of the index
prefix_arityint(11) unsignedNOPRINULLIndex prefix length. 1 for the first keypart, 2 for the first two, and so on. InnoDB's extended keys are supported.
avg_frequencydecimal(12,4)YESNULLAverage number of records one will find for given values of (keypart1, keypart2, ..), provided the values will be found in the table.

It is possible to manually update the table. See Manual updates to statistics tables for details.

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