W3cubDocs

/MariaDB

Information Schema KEY_CACHES Table

MariaDB 5.2.0

The KEY_CACHES table was introduced in MariaDB 5.2.0

The Information Schema KEY_CACHES table shows statistics about the segmented key cache, which was introduced in MariaDB 5.2.0.

It contains the following columns:

Column Name	Description
`KEY_CACHE_NAME`	The name of the key cache
`SEGMENTS`	total number of segments (set to `NULL` for regular key caches)
`SEGMENT_NUMBER`	segment number (set to `NULL` for any regular key caches and for rows containing aggregation statistics for segmented key caches)
`FULL_SIZE`	memory for cache buffers/auxiliary structures
`BLOCK_SIZE`	size of the blocks
`USED_BLOCKS`	number of currently used blocks
`UNUSED_BLOCKS`	number of currently unused blocks
`DIRTY_BLOCKS`	number of currently dirty blocks
`READ_REQUESTS`	number of read requests
`READS`	number of actual reads from files into buffers
`WRITE_REQUESTS`	number of write requests
`WRITES`	number of actual writes from buffers into files

Example

SELECT * FROM information_schema.KEY_CACHES \G
********************** 1. row **********************
KEY_CACHE_NAME: default
SEGMENTS: NULL
SEGMENT_NUMBER: NULL
     FULL_SIZE: 134217728
    BLOCK_SIZE: 1024
   USED_BLOCKS: 36
 UNUSED_BLOCKS: 107146
  DIRTY_BLOCKS: 0
 READ_REQUESTS: 40305
         READS: 21
WRITE_REQUESTS: 19239
        WRITES: 358

Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.

© 2019 MariaDB
Licensed under the Creative Commons Attribution 3.0 Unported License and the GNU Free Documentation License.
https://mariadb.com/kb/en/information-schema-key_caches-table/