## Notes 

•This table is useful primarily for expert-level performance monitoring, or when developing performance- related extensions for MySQL. 

•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. 

## 26.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table 

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 15.15.5, “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. 

## Examples 

• N_CACHED_PAGES 

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

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

mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_CACHED_INDEXES WHERE INDEX_ID=65\G *************************** 1. row *************************** SPACE_ID: 4294967294 INDEX_ID: 65 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. 

## Notes 

SELECT tables.NAME AS table_name, indexes.NAME AS index_name, cached.N_CACHED_PAGES AS n_cached_pages FROM INFORMATION_SCHEMA.INNODB_CACHED_INDEXES AS cached, INFORMATION_SCHEMA.INNODB_INDEXES AS indexes, INFORMATION_SCHEMA.INNODB_TABLES AS tables WHERE cached.INDEX_ID = indexes.INDEX_ID AND indexes.TABLE_ID = tables.TABLE_ID; 

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

