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MySQL 5.7 Reference Manual  /  ...  /  The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table

24.31.3 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.

For related usage information and examples, see Section 14.15.5, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables”.

Table 24.3 INNODB_BUFFER_POOL_STATS Columns

Column name Description
POOL_ID Buffer Pool ID. A unique identifier to distinguish between multiple buffer pool instances.
POOL_SIZE The InnoDB buffer pool size in pages.
FREE_BUFFERS The number of free pages in the InnoDB buffer pool
DATABASE_PAGES The number of pages in the InnoDB buffer pool containing data. The number includes both dirty and clean pages.
OLD_DATABASE_PAGES The number of pages in the old 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 the InnoDB 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 LRU IO total
LRU_IO_CURRENT LRU IO for the current interval
UNCOMPRESS_TOTAL 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: 18
NOT_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 primarily useful for expert-level performance monitoring, or when developing performance-related extensions for MySQL.

  • Use DESCRIBE or SHOW COLUMNS to view additional information about the columns of this table including data types and default values.

  • You must have the PROCESS privilege to query this table.


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