20.28.7. The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table
The INNODB_BUFFER_PAGE_LRU table holds
information about the pages in the InnoDBbuffer pool, in particular
how they are ordered that determines which pages to
evict from the buffer pool
when it becomes full.
The definition for this page is the same as for
INNODB_BUFFER_PAGE,
except this table has an LRU_POSITION column
instead of BLOCK_ID.
Notes:
This table is primarily useful for expert-level performance
monitoring, or when developing performance-related extensions
for MySQL.
Since the INFORMATION_SCHEMA is a
general-purpose way to monitor the MySQL server, use this
table rather than the corresponding InnoDB
system table for any new monitoring application you develop.
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.
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