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MySQL 8.0 Reference Manual  / ...  / INFORMATION_SCHEMA Tables  / INFORMATION_SCHEMA InnoDB Tables  /  The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table

28.4.4 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table

TheINNODB_BUFFER_POOL_STATS table provides much of the same buffer pool information provided inSHOW ENGINE INNODB STATUS output. Much of the same information may also be obtained usingInnoDB buffer poolserver status variables.

The idea of making pages in the buffer pool“young” or“not young” refers to transferring them between thesublists 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 ofeviction.

For related usage information and examples, seeSection 17.15.5, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables”.

TheINNODB_BUFFER_POOL_STATS table has these columns:

  • POOL_ID

    The buffer pool ID. This is an identifier to distinguish between multiple buffer pool instances.

  • POOL_SIZE

    TheInnoDB buffer pool size in pages.

  • FREE_BUFFERS

    The number of free pages in theInnoDB buffer pool.

  • DATABASE_PAGES

    The number of pages in theInnoDB buffer pool containing data. This number includes both dirty and clean pages.

  • OLD_DATABASE_PAGES

    The number of pages in theold buffer pool sublist.

  • MODIFIED_DATABASE_PAGES

    The number of modified (dirty) database pages.

  • PENDING_DECOMPRESS

    The number of pages pending decompression.

  • PENDING_READS

    The number of pending reads.

  • PENDING_FLUSH_LRU

    The number of pages pending flush in the LRU.

  • PENDING_FLUSH_LIST

    The number of pages pending flush in the flush list.

  • PAGES_MADE_YOUNG

    The number of pages made young.

  • PAGES_NOT_MADE_YOUNG

    The number of pages not made young.

  • PAGES_MADE_YOUNG_RATE

    The number of pages made young per second (pages made young since the last printout / time elapsed).

  • PAGES_MADE_NOT_YOUNG_RATE

    The number of pages not made per second (pages not made young since the last printout / time elapsed).

  • NUMBER_PAGES_READ

    The number of pages read.

  • NUMBER_PAGES_CREATED

    The number of pages created.

  • NUMBER_PAGES_WRITTEN

    The number of pages written.

  • PAGES_READ_RATE

    The number of pages read per second (pages read since the last printout / time elapsed).

  • PAGES_CREATE_RATE

    The number of pages created per second (pages created since the last printout / time elapsed).

  • PAGES_WRITTEN_RATE

    The number of pages written per second (pages written since the last printout / time elapsed).

  • NUMBER_PAGES_GET

    The number of logical read requests.

  • HIT_RATE

    The buffer pool hit rate.

  • YOUNG_MAKE_PER_THOUSAND_GETS

    The number of pages made young per thousand gets.

  • NOT_YOUNG_MAKE_PER_THOUSAND_GETS

    The number of pages not made young per thousand gets.

  • NUMBER_PAGES_READ_AHEAD

    The number of pages read ahead.

  • NUMBER_READ_AHEAD_EVICTED

    The number of pages read into theInnoDB buffer pool by the read-ahead background thread that were subsequently evicted without having been accessed by queries.

  • READ_AHEAD_RATE

    The read-ahead rate per second (pages read ahead since the last printout / time elapsed).

  • READ_AHEAD_EVICTED_RATE

    The number of read-ahead pages evicted without access per second (read-ahead pages not accessed since the last printout / time elapsed).

  • LRU_IO_TOTAL

    Total LRU I/O.

  • LRU_IO_CURRENT

    LRU I/O for the current interval.

  • UNCOMPRESS_TOTAL

    The total number of pages decompressed.

  • UNCOMPRESS_CURRENT

    The number of pages decompressed in the current interval.

Example

mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_BUFFER_POOL_STATS\G*************************** 1. row ***************************                         POOL_ID: 0                       POOL_SIZE: 8192                    FREE_BUFFERS: 1                  DATABASE_PAGES: 8085              OLD_DATABASE_PAGES: 2964         MODIFIED_DATABASE_PAGES: 0              PENDING_DECOMPRESS: 0                   PENDING_READS: 0               PENDING_FLUSH_LRU: 0              PENDING_FLUSH_LIST: 0                PAGES_MADE_YOUNG: 22821            PAGES_NOT_MADE_YOUNG: 3544303           PAGES_MADE_YOUNG_RATE: 357.62602199870594       PAGES_MADE_NOT_YOUNG_RATE: 0               NUMBER_PAGES_READ: 2389            NUMBER_PAGES_CREATED: 12385            NUMBER_PAGES_WRITTEN: 13111                 PAGES_READ_RATE: 0               PAGES_CREATE_RATE: 0              PAGES_WRITTEN_RATE: 0                NUMBER_PAGES_GET: 33322210                        HIT_RATE: 1000    YOUNG_MAKE_PER_THOUSAND_GETS: 18NOT_YOUNG_MAKE_PER_THOUSAND_GETS: 0         NUMBER_PAGES_READ_AHEAD: 2024       NUMBER_READ_AHEAD_EVICTED: 0                 READ_AHEAD_RATE: 0         READ_AHEAD_EVICTED_RATE: 0                    LRU_IO_TOTAL: 0                  LRU_IO_CURRENT: 0                UNCOMPRESS_TOTAL: 0              UNCOMPRESS_CURRENT: 0

Notes

  • This table is useful primarily for expert-level performance monitoring, or when developing performance-related extensions for MySQL.

  • You must have thePROCESS privilege to query this table.

  • Use theINFORMATION_SCHEMACOLUMNS table or theSHOW COLUMNS statement to view additional information about the columns of this table, including data types and default values.