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20.30.3. The INFORMATION_SCHEMA INNODB_CMPMEM andINNODB_CMPMEM_RESET Tables

The INNODB_CMPMEM and INNODB_CMPMEM_RESET tables contain status information on compressed pages within the InnoDB buffer pool.

Table 20.3. Columns of INNODB_CMPMEM and INNODB_CMPMEM_RESET

Column name Description
PAGE_SIZE Block size in bytes. Each record of this table describes blocks of this size.
PAGES_USED Number of blocks of the size PAGE_SIZE that are currently in use.
PAGES_FREE Number of blocks of the size PAGE_SIZE that are currently available for allocation. This column shows the external fragmentation in the memory pool. Ideally, these numbers should be at most 1.
RELOCATION_OPS Number of times a block of the size PAGE_SIZE has been relocated. The buddy system can relocate the allocated "buddy neighbor" of a freed block when it tries to form a bigger freed block. Reading from the table INNODB_CMPMEM_RESET resets this count.
RELOCATION_TIME Total time in microseconds spent in relocating blocks of the size PAGE_SIZE. Reading from the tableINNODB_CMPMEM_RESET resets this count.

Notes: