INNODB_BUFFER_PAGE_LRU - xiaoboluo768/mysql-system-schema GitHub Wiki

该表提供查询缓冲池中的页面信息，与INNODB_BUFFER_PAGE表不同，INNODB_BUFFER_PAGE_LRU表保存有关innodb buffer pool中的页如何进入LRU链表以及在buffer pool不够用时确定需要从缓冲池中逐出哪些页

与INNODB_BUFFER_PAGE表一样，不要在生产系统上查询，查询该表可能需要MySQL分配一大块连续的内存，且分配用于查询该表的内存时可能会导致内存不足错误，特别是buffer pool分配大小超过数GB的数据库实例中。另外，查询此表时MySQL需要遍历LRU链表，遍历时会锁定缓冲池的数据结构，这会降低数据库实例的并发性能，特别是buffer pool分配大小超过数GB的数据库实例中

该表为Memory引擎临时表

表定义语句

CREATE TEMPORARY TABLE `INNODB_BUFFER_PAGE_LRU` (
  `POOL_ID` bigint(21) unsigned NOT NULL DEFAULT '0',
  `LRU_POSITION` bigint(21) unsigned NOT NULL DEFAULT '0',
  `SPACE` bigint(21) unsigned NOT NULL DEFAULT '0',
  `PAGE_NUMBER` bigint(21) unsigned NOT NULL DEFAULT '0',
  `PAGE_TYPE` varchar(64) DEFAULT NULL,
  `FLUSH_TYPE` bigint(21) unsigned NOT NULL DEFAULT '0',
  `FIX_COUNT` bigint(21) unsigned NOT NULL DEFAULT '0',
  `IS_HASHED` varchar(3) DEFAULT NULL,
  `NEWEST_MODIFICATION` bigint(21) unsigned NOT NULL DEFAULT '0',
  `OLDEST_MODIFICATION` bigint(21) unsigned NOT NULL DEFAULT '0',
  `ACCESS_TIME` bigint(21) unsigned NOT NULL DEFAULT '0',
  `TABLE_NAME` varchar(1024) DEFAULT NULL,
  `INDEX_NAME` varchar(1024) DEFAULT NULL,
  `NUMBER_RECORDS` bigint(21) unsigned NOT NULL DEFAULT '0',
  `DATA_SIZE` bigint(21) unsigned NOT NULL DEFAULT '0',
  `COMPRESSED_SIZE` bigint(21) unsigned NOT NULL DEFAULT '0',
  `COMPRESSED` varchar(3) DEFAULT NULL,
  `IO_FIX` varchar(64) DEFAULT NULL,
  `IS_OLD` varchar(3) DEFAULT NULL,
  `FREE_PAGE_CLOCK` bigint(21) unsigned NOT NULL DEFAULT '0'
) ENGINE=MEMORY DEFAULT CHARSET=utf8

表字段含义

INNODB_BUFFER_PAGE_LRU表与INNODB_BUFFER_PAGE表具有相同的列，但INNODB_BUFFER_PAGE_LRU表多了一个LRU_POSITION列，少了一个BLOCK_ID列。LRU_POSITION列表示页在LRU链表中的位置

表记录内容示例

admin@localhost : information_schema 06:35:36> select * from INNODB_BUFFER_PAGE_LRU where TABLE_NAME='`sbtest`.`sbtest1`' limit 1\G;
*************************** 1. row ***************************
            POOL_ID: 0
      LRU_POSITION: 192
              SPACE: 32
        PAGE_NUMBER: 108304
          PAGE_TYPE: INDEX
        FLUSH_TYPE: 0
          FIX_COUNT: 0
          IS_HASHED: NO
NEWEST_MODIFICATION: 0
OLDEST_MODIFICATION: 0
        ACCESS_TIME: 0
        TABLE_NAME: `sbtest`.`sbtest1`
        INDEX_NAME: i_c
    NUMBER_RECORDS: 124
          DATA_SIZE: 16120
    COMPRESSED_SIZE: 0
        COMPRESSED: NO
            IO_FIX: IO_NONE
            IS_OLD: NO
    FREE_PAGE_CLOCK: 0
1 row in set (0.00 sec)

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INNODB_BUFFER_PAGE_LRU - xiaoboluo768/mysql-system-schema GitHub Wiki

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