20.28.8 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table

The INNODB_BUFFER_POOL_STATS table provides much of the same buffer pool information provided in SHOW ENGINE INNODB STATUS output. Much of the same information may also be obtained using InnoDB buffer pool server status variables.

The idea of making pages in the buffer pool young or not young refers to transferring them between the sublists at the head and tail of the buffer pool data structure. Pages made young take longer to age out of the buffer pool, while pages made not young are moved much closer to the point of eviction.

Table 20.7 INNODB_BUFFER_POOL_STATS Columns

Column nameDescription
POOL_IDBuffer Pool ID. A unique identifier to distinguish between multiple buffer pool instances.
POOL_SIZEThe InnoDB buffer pool size in pages.
FREE_BUFFERSThe number of free pages in the InnoDB buffer pool
DATABASE_PAGESThe number of pages in the InnoDB buffer pool containing data. The number includes both dirty and clean pages.
OLD_DATABASE_PAGESThe number of pages in the old buffer pool sublist.
MODIFIED_DATABASE_PAGESThe number of modified (dirty) database pages
PENDING_DECOMPRESSThe number of pages pending decompression
PENDING_READSThe number of pending reads
PENDING_FLUSH_LRUThe number of pages pending flush in the LRU
PENDING_FLUSH_LISTThe number of pages pending flush in the flush list
PAGES_MADE_YOUNGThe number of pages made young
PAGES_NOT_MADE_YOUNGThe number of pages not made young
PAGES_MADE_YOUNG_RATEThe number of pages made young per second (pages made young since the last printout / time elapsed)
PAGES_MADE_NOT_YOUNG_RATEThe number of pages not made per second (pages not made young since the last printout / time elapsed)
NUMBER_PAGES_READThe number of pages read
NUMBER_PAGES_CREATEDThe number of pages created
NUMBER_PAGES_WRITTENThe number of pages written
PAGES_READ_RATEThe number of pages read per second (pages read since the last printout / time elapsed)
PAGES_CREATE_RATEThe number of pages created per second (pages created since the last printout / time elapsed)
PAGES_WRITTEN_RATEThe number of pages written per second (pages written since the last printout / time elapsed)
NUMBER_PAGES_GETThe number of logical read requests.
HIT_RATEThe buffer pool hit rate
YOUNG_MAKE_PER_THOUSAND_GETSThe number of pages made young per thousand gets
NOT_YOUNG_MAKE_PER_THOUSAND_GETSThe number of pages not made young per thousand gets
NUMBER_PAGES_READ_AHEADThe number of pages read ahead
NUMBER_READ_AHEAD_EVICTEDThe number of pages read into the InnoDB buffer pool by the read-ahead background thread that were subsequently evicted without having been accessed by queries.
READ_AHEAD_RATEThe read ahead rate per second (pages read ahead since the last printout / time elapsed)
READ_AHEAD_EVICTED_RATEThe number of read ahead pages evicted without access per second (read ahead pages not accessed since the last printout / time elapsed)
LRU_IO_TOTALLRU IO total
LRU_IO_CURRENTLRU IO for the current interval
UNCOMPRESS_TOTALTotal number of pages decompressed
UNCOMPRESS_CURRENTThe number of pages decompressed in the current interval

Notes: