Information Schema KEY_CACHES Table

The Information Schema KEY_CACHES table shows statistics about the segmented key cache,.

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
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https://mariadb.com/kb/en/information-schema-key_caches-table/