… MyISAM does not cache data, only indexes. MyISAM assumes OS cache is good enough and uses pread/pwrite system calls for reading/writing… faster for SELECT/UPDATE/INSERT inside file queries, and no performance gain (maybe a bit slower) for INSERT at the end… memory mapping gives benefit in different cases. The value of performance gain depends of count replaced pread/pwrite calls. For select…
Post: MySQL VIEW as performance troublemaker
August 12, 2007 By 57 Comments
… used to help in writing the queries – to keep queries simple without really thinking how it affects server performance. Even worse than…` text NOT NULL, PRIMARY KEY (`user_id`,`comment_id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 So how would you get number of… table execution method. VIEWs can be used with very small performance overhead but only in case they are used with caution…
Post: MyISAM concurrent insert
June 13, 2006 By 12 Comments
… processing range-queries. The reason of problems is POSIX read-write locks, which are used to protect key_buffer from concurrent… user-space (Solaris) or kernel-space (Linux). Some results for MyISAM table, query SELECT id FROM sbtest WHERE id BETWEEN N… than disabling concurrent-insert with –skip-concurrent-insert can improve MyISAM performance. As I said the reason of bad scalability is rw…
Post: Using Multiple Key Caches for MyISAM Scalability
November 26, 2008 By 8 Comments
…have written before – MyISAM Does Not Scale, or it does quite well – two main… are not the issue for Read Only workload and write intensive workloads can be dealt with by using with … key cache creation exercise you probably wonder how much performance gains should you expect. In fact it can be …
Post: MySQL Performance Blog now uses Sphinx for Site Search
February 15, 2008 By 52 Comments
…if I wanted to find something on MySQL Performance Blog. Today we have published new search …just want to test it a bit more and write proper documentation before announcing. If you would …Sphinx query language to search phrases or Search MyISAM in post title. Besides basic search functionality …
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
… table locks reporting queries can affect web site performance dramatically. Sometimes instead of using slave you may…server – you may read data from slave and write it to the master (selects often contribute most… even careful file transfer if you’re using MyISAM tables. Chop it If you can’t execute…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…write_lock_countblogpercona.commanual memlockblogpercona.commanual min_examined_row_limitblogpercona.commanual myisam_block_sizeblogpercona.commanual myisam_data_pointer_sizeblogpercona.commanual myisam…
Post: How much overhead is caused by on disk temporary tables
August 16, 2007 By 26 Comments
… writes which kill performance. The problem with writes is OS can delay writes only for fixed amount of time and when it has to perform… for MyISAM temporary tables performance to avoid OS writes OS Write cache is not as efficient as I would hope, at least on Linux Performance of Disk MyISAM…
Post: MySQL File System Fragmentation Benchmarks
March 21, 2008 By 28 Comments
… rows per sec: 11826.941546043sec. tables: 1000; total records: 10000000; write rows per sec: 2838.9678814081 , reads rows per sec: 13758… affects table scan performance nadly – MyISAM suffers worse than Innodb – Innodb extent allocation works (perhaps would be good option for MyISAM as well…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
…) which can help significantly. delay_key_write Delay updating indexes for MyISAM tables. Good for performance but tables will be badly corrupted on… for MyISAM and MEMORY tables. max_write_lock_count Variable which may save you from read starvation if there are constant writes to the table. Works with table locks so again practically applies to MYISAM and MEMORY tables. preload…
