…_table variable. i executed the following query to know the fragmentation SELECT TABLE_SCHEMA, TABLE_NAME, CONCAT(ROUND(data_length / ( 1024…(free space) after this I executed alter table abc engine=innodb and re-executed SELECT TABLE_SCHEMA, TABLE_NAME, CONCAT(ROUND… not be defragmented. is there any other way to defragment innodb tables? thanks Kuldeep
Post: InnoDB: look after fragmentation
November 5, 2009 By 12 Comments
…: 38530 InnoDB_IO_r_bytes: 631275520 InnoDB_IO_r_wait: 0.204893 # InnoDB_rec_lock_wait: 0.000000 InnoDB_queue_wait: 0.000000 # InnoDB_pages…: InnoDB fragmentation may hurt your query significantly, especially when data is not in buffer_pool and execution goes to read from disk Fragmentation… To check if you query affected by fragmentation you can use Innodb_scan_pages_contiguous ; Innodb_scan_pages_jumpy statistics in 5.0…
Post: Learning about MySQL Table Fragmentation
May 1, 2008 By 19 Comments
… single page (16K reads). In case of non fragmented table you would see Innodb sequential read-ahead kick in which does reads… not logically fragmented and Innodb is reading data in large blocks – this can happen in case Innodb table file is itself fragmented. To check…. P.S It would be cool to get Innodb objects (data and Index) fragmentation statistics which actually should not be that hard…
Post: MySQL File System Fragmentation Benchmarks
March 21, 2008 By 28 Comments
… Innodb tables on ext3 filesystem. Here is what I found: The fragmentation we speak in this article is filesystem fragmentation or internal table fragmentation… suffers worse than Innodb – Innodb extent allocation works (perhaps would be good option for MyISAM as well) – Innodb suffers fragmentation less if it stores…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
…. The first 32 pages of a segment are allocated from ‘fragment extents’ where any individual page can be allocated to whatever…, and also it can release individual pages from its 32 ‘fragment extent’ pages. PZ: This is the reason why when you… may not see a “free space” in Innodb tablespace to grow significantly. Q6: Does Innodb policy replacement algorithm takes into account page…
Post: Improved InnoDB fast index creation
November 6, 2011 By 4 Comments
… important thing that is worth mentioning is fragmentation. Fast index creation results in much less fragmented indexes because records are inserted in… TABLE OPTIMIZE TABLE is mapped to ALTER TABLE … ENGINE=InnoDB for InnoDB tables and thus, is just a special case of the… part of a FOREIGN KEY constraint; mysqldump –innodb-optimize-keys ignores foreign keys because InnoDB requires a full table rebuild on foreign…
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
… a facility we can run to show any table / index fragmentation, without having to run the OPTIMIZE? HT: Since OPTIMIZE rebuilds… table scan would be fast. Maybe the table has become fragmented? Or maybe you have not inserted in the ascending order… not showed up in “show innodb statusâ€. select * from table where id=5 show innodb status: Hash table size 10624987, used…
Post: Innodb Double Write
August 4, 2006 By 23 Comments
… just between their execution. Reasons for splitting could be file fragmentation – most file systems use 4K block sizes by default so 16K could use more than one fragment. Also if software RAID is used page may come on… term log file allocated inside Innodb tablespace – it contains space for 100 pages. When Innodb flushes pages from Innodb buffer pool it does…
Post: Quickly preloading Innodb tables in the buffer pool
May 1, 2008 By 9 Comments
… native support. It would be great if Innodb would implement command to preload table to Innodb buffer pool, which would simply go…=0 This works relatively well (though can be slow for fragmented tables) but it does not preload indexes in memory neither… best preload speed ? It depends – depending on key/clustered key fragmentation it may be faster to run queries one by one…
Post: Pretty-formatted index fragmentation with xtrabackup
March 15, 2011 By 4 Comments
… the Perl script) has support for printing out stats on InnoDB tables and indexes. This can be useful to examine whether… formats the stats output nicely to give an overview of fragmentation. It’s an initial draft, and if you find issues…
