… pt-online-schema-change performs the ALTER without any locking. Client applications can continue reading and writing the table with no interruption… use. The key is that it is replication-aware and inspects replicas, throttles its operation to avoid causing replication delay, watches for…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…delay_key_writeblogpercona.commanual Delayed_errorsblogpercona.commanual delayed_insert_limitblogpercona.commanual Delayed_insert_threadsblogpercona.commanual delayed_insert_timeoutblogpercona.commanual delayed_queue_sizeblogpercona.commanual Delayed_writesblogpercona.commanual des_key…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
…. delay_key_write Delay updating indexes for MyISAM tables. Good for performance but tables will be badly corrupted on crash. delayed_insert_limit, delayed_insert_timeout, delayed_queue_size Delayed inserts configuration. Technically…
Post: Using MyISAM in production
June 17, 2006 By 35 Comments
… only have indexes cached in key_buffer while data is cached in OS cache. It is performance issue as system call is… wipe OS cache which you hoped for causing unexpected slowdowns. delay_key_writes Whatever way you enable this option – globally, for table or… been running for years survining many crashes. If you enable delay_key_writes it drastically changes. Now in case of crash your index…
Post: MySQL MyISAM Active Active Clustering - looking for trouble ?
March 15, 2007 By 4 Comments
… certain rules like enabling external locking, disabling query cache and delayed key writes etc. This is as far as many articles on this… key cache have to be invalidated with remote writes which makes even less efficient. So this configuration would unlikely be well performing compared…
Post: How much overhead is caused by on disk temporary tables
August 16, 2007 By 26 Comments
… all key blocks from temporary table index, so we get a lot of key 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…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
… their own clients, with no delays. Finally, the analysis is usually multi… you need and get the performance you need. Because I’ve … initial insertion, because you can write CSV files with any programming language….are already inconvenient limitations on some key parts of partitioning, such as …
Post: Performance gotcha of MySQL memory tables
February 1, 2008 By 5 Comments
… matches or range lookups. This is however not performance gotcha I’m going to write about. There is one more thing you… unusual is – the key cardinality affects performance even when this key is not directly used for lookup. Changing the key c to be BTREE… Innodb could delay writes and do all the changes directly in memory. MyISAM however had to perform number of random writes to the key file…
Post: The performance effects of new patches
September 9, 2008 By 14 Comments
… eventually). There are no delays between transactions (no thinking time, no keying time), it uses MySQL … number of blocks flushed at once. (flushing: writing modified db pages by flush_list order) …are using fast RAID storage, and/or observe performance decrease caused by shortage of free buffers …
Post: Performance improvements in Percona 5.0.83 and XtraDB
July 14, 2009 By 27 Comments
…delay in our releases, part of this…with performance trying to align XtraDB performance with MySQL 5.4 ® and also port all performance … here http://spreadsheets.google.com/ccc?key=tOWmcwiHDD6-zNeXwe2k3Og And let me post some… of adaptive_checkpoint, and he will write about it eventually. But this is …
