Change Buffer Name Description I/O sum The total number of buffer pool LRU list pages accessed. I/O cur The total number of buffer pool LRU list pages accessed in the current interval. I/O unzip sum The total number of buffer pool unzip_LRU list pages decompressed. I/O unzip cur The total number of buffer pool unzip_LRU list pages decompressed in the current interval. Notes 15.5.2 Change Buffer 3011 The change buffer is a special data structure that caches changes to secondary index pages when those pages are not in the buffer pool. The buffered changes, which may result from  INSERT ,  UPDATE , or DELETE  operations (DML), are merged later when the pages are loaded into the buffer pool by other read operations. Buffer pool server status variables and the  INNODB_BUFFER_POOL_STATS  table provide many of the same buffer pool metrics found in  InnoDB  Standard Monitor output. For more information, see Example 15.10, “Querying the INNODB_BUFFER_POOL_STATS Table” . • not (young-making rate)  is the average hit rate at which page accesses have not resulted in making pages young due to the delay defined by  innodb_old_blocks_time  not being met, or due to page hits in the new sublist that did not result in pages being moved to the head. This rate accounts for all buffer pool page accesses, not just accesses for pages in the old sublist. •The  young-making  rate accounts for all buffer pool page accesses, not just accesses for pages in the old sublist. The  young-making  rate and  not  rate do not normally add up to the overall buffer pool hit rate. Page hits in the old sublist cause pages to move to the new sublist, but page hits in the new sublist cause pages to move to the head of the list only if they are a certain distance from the head. •The  non-youngs/s  metric is applicable only to old pages. It is based on the number of page accesses. There can be multiple accesses for a given page, all of which are counted. If you do not see a higher non-youngs/s  value when performing large table scans (and a higher  youngs/s  value), increase the delay value. See Section 15.8.3.3, “Making the Buffer Pool Scan Resistant” . •The  youngs/s  metric is applicable only to old pages. It is based on the number of page accesses. There can be multiple accesses for a given page, all of which are counted. If you see very low  youngs/ s  values when there are no large scans occurring, consider reducing the delay time or increasing the percentage of the buffer pool used for the old sublist. Increasing the percentage makes the old sublist larger so that it takes longer for pages in that sublist to move to the tail, which increases the likelihood that those pages are accessed again and made young. See Section 15.8.3.3, “Making the Buffer Pool Scan Resistant” .