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25.39.4 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table

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The INNODB_CACHED_INDEXES table reports the number of index pages cached in the InnoDB buffer pool for each index.

For related usage information and examples, see Section 15.14.5, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables”.

The INNODB_CACHED_INDEXES table has these columns:

  • SPACE_ID

    The tablespace ID.

  • INDEX_ID

    An identifier for the index. Index identifiers are unique across all the databases in an instance.

  • N_CACHED_PAGES

    The number of index pages cached in the InnoDB buffer pool.

Examples

This query returns the number of index pages cached in the InnoDB buffer pool for a specific index:

  1. mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_CACHED_INDEXES WHERE INDEX_ID=65\G
  2. *************************** 1. row ***************************
  3.       SPACE_ID: 4294967294
  4.       INDEX_ID: 65
  5. N_CACHED_PAGES: 45

This query returns the number of index pages cached in the InnoDB buffer pool for each index, using the INNODB_INDEXES and INNODB_TABLES tables to resolve the table name and index name for each INDEX_ID value.

  1. SELECT
  2.   tables.NAME AS table_name,
  3.   indexes.NAME AS index_name,
  4.   cached.N_CACHED_PAGES AS n_cached_pages
  5. FROM
  6.   INFORMATION_SCHEMA.INNODB_CACHED_INDEXES AS cached,
  7.   INFORMATION_SCHEMA.INNODB_INDEXES AS indexes,
  8.   INFORMATION_SCHEMA.INNODB_TABLES AS tables
  9. WHERE
  10.   cached.INDEX_ID = indexes.INDEX_ID
  11.   AND indexes.TABLE_ID = tables.TABLE_ID;

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Notes

  • You must have the PROCESS privilege to query this table.

  • Use the INFORMATION_SCHEMA COLUMNS table or the SHOW COLUMNS statement to view additional information about the columns of this table, including data types and default values.


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Document created the 26/06/2006, last modified the 26/10/2018
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