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 14.18.3, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables”.
Table 21.3 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: 0
DATABASE_PAGES: 8014
OLD_DATABASE_PAGES: 2938
MODIFIED_DATABASE_PAGES: 0
PENDING_DECOMPRESS: 0
PENDING_READS: 0
PENDING_FLUSH_LRU: 0
PENDING_FLUSH_LIST: 0
PAGES_MADE_YOUNG: 7380
PAGES_NOT_MADE_YOUNG: 0
PAGES_MADE_YOUNG_RATE: 0
PAGES_MADE_NOT_YOUNG_RATE: 0
NUMBER_PAGES_READ: 2723
NUMBER_PAGES_CREATED: 12657
NUMBER_PAGES_WRITTEN: 16181
PAGES_READ_RATE: 0
PAGES_CREATE_RATE: 0
PAGES_WRITTEN_RATE: 0
NUMBER_PAGES_GET: 28952710
HIT_RATE: 1000
YOUNG_MAKE_PER_THOUSAND_GETS: 0
NOT_YOUNG_MAKE_PER_THOUSAND_GETS: 0
NUMBER_PAGES_READ_AHEAD: 2469
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
1 row in set (0.00 sec)
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.