The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table • IS_OLD • FREE_PAGE_CLOCK Notes Example 26.4.4 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table 4848 •This table is useful primarily for expert-level performance monitoring, or when developing performance- related extensions for MySQL. •You must have the  PROCESS  privilege to query this table. •Use the  INFORMATION_SCHEMA COLUMNS  table or the  SHOW COLUMNS  statement to view additional information about the columns of this table, including data types and default values. •Querying this table can require MySQL to allocate a large block of contiguous memory, more than 64 bytes times 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. •When tables, table rows, partitions, or indexes are deleted, associated pages remain in the buffer pool until space is required for other data. The  INNODB_BUFFER_PAGE_LRU  table reports information about these pages until they are evicted from the buffer pool. For more information about how the  InnoDB manages buffer pool data, see Section 15.5.1, “Buffer Pool” . Whether the block is in the sublist of old blocks in the LRU list. The value of the  freed_page_clock  counter when the block was the last placed at the head of the LRU list. The  freed_page_clock  counter tracks the number of blocks removed from the end of the LRU list. mysql>  SELECT * FROM INFORMATION_SCHEMA.INNODB_BUFFER_PAGE_LRU LIMIT 1\G *************************** 1. row *************************** POOL_ID: 0 LRU_POSITION: 0 SPACE: 97 PAGE_NUMBER: 1984 PAGE_TYPE: INDEX FLUSH_TYPE: 1 FIX_COUNT: 0 IS_HASHED: YES NEWEST_MODIFICATION: 719490396 OLDEST_MODIFICATION: 0 ACCESS_TIME: 3378383796 TABLE_NAME: ‘employees‘.‘salaries‘ INDEX_NAME: PRIMARY NUMBER_RECORDS: 468 DATA_SIZE: 14976 COMPRESSED_SIZE: 0 COMPRESSED: NO IO_FIX: IO_NONE IS_OLD: YES FREE_PAGE_CLOCK: 0