INNODB_BUFFER_PAGE_LRU table holds
information about the pages in the
buffer pool, in particular
how they are ordered in the LRU list that determines which pages
to evict from the buffer pool
when it becomes full.
The definition for this page is the same as for
except this table has an
Table 21.17 INNODB_BUFFER_PAGE Columns
|Buffer Pool ID. An identifier to distinguish between multiple buffer pool instances.|
|The position of the page in the LRU list.|
|Tablespace ID. Uses the same value as in
|Page type string. One of |
|Number of threads using this block within the buffer pool. When zero, the block is eligible to be evicted.|
|Whether hash index has been built on this page.|
|Log Sequence Number of the youngest modification.|
|Log Sequence Number of the oldest modification.|
|An abstract number used to judge the first access time of the page.|
|Name of the table the page belongs to.|
|Name of the index the page belongs to. It can be the name of a clustered index or a secondary index.|
|Number of records within the page.|
|Sum of the sizes of the records.|
|Compressed page size. Null for pages that are not compressed.|
|Page state. A page with valid data has one of the following states:
|Specifies whether any I/O is pending for this page:
|The value of the |
This table is primarily useful for expert-level performance monitoring, or when developing performance-related extensions for MySQL.
Querying this table can require MySQL to allocate a large block of contiguous memory, more than 64 bytes time the number of active pages in the buffer pool. This allocation could potentially cause an out-of-memory error, especially for systems with multi-gigabyte buffer pools.
Querying this table requires MySQL to lock the data structure representing the buffer pool while traversing the LRU list, which can reduce concurrency, especially for systems with multi-gigabyte buffer pools.