21.29.3 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables

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

Table 21.3 Columns of INNODB_CMPMEM and INNODB_CMPMEM_RESET

Column nameDescription
PAGE_SIZEBlock size in bytes. Each record of this table describes blocks of this size.
BUFFER_POOL_INSTANCEA unique identifier for the buffer pool instance.
PAGES_USEDNumber of blocks of the size PAGE_SIZE that are currently in use.
PAGES_FREENumber 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_OPSNumber 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_TIMETotal time in microseconds spent in relocating blocks of the size PAGE_SIZE. Reading from the table INNODB_CMPMEM_RESET resets this count.

Notes: