…with REPEATABLE READ transaction isolation level. mysql> show create table t\G *************************** 1. row …write data, the isolation is READ COMMITED so you can’t update/delete that row, because it doesn’t exist anymore. I hope this example clarify your questions, if not, feel free…
Post: How to Monitor MySQL with Percona's Nagios Plugins
February 22, 2012 By 8 Comments
… server installations) or a system administration mistake to delete one of MySQL‘s log or data files from disk. The database server will… server and lose your data permanently. The pmp-check-mysql-deleted-files plugin will alert when files have been deleted but remain open via… process consuming too much memory and/or for too little free memory in general. This plugin requires careful configuration because it…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…MySQL … Com_delete_multiblogpercona….data_pending_readsblogpercona.commanual Innodb_data_pending_writesblogpercona.commanual Innodb_data_readblogpercona.commanual Innodb_data_readsblogpercona.commanual Innodb_data_writesblogpercona.commanual Innodb_data…free_blocksblogpercona.commanual Qcache_free…
Post: How to debug long-running transactions in MySQL
March 8, 2011 By 6 Comments
… a script that will let data accumulate or fill up the disk. #!/bin/bash # Begin by deleting things more than 7 days…}” ]; then echo “Exiting, not enough free space (${full}%, ${avail}MB free)”>&2 exit 1 fi host=$(mysql -ss -e ‘SELECT p.HOST FROM… port 3306 and port ${port} > /root/tcpdumps/`date +%s`-tcpdump & mysql -e ‘show innodb status\Gshow full processlist’ > /root/tcpdumps/`date +%s…
Post: Flexviews is a working scalable database transactional memory example
May 19, 2011 By 3 Comments
…for creating materialized views for MySQL data sets. The tool is for MySQL, but the methods are …(Flexviews uses only composable operations even for deletes over “non-distributable aggregate functions”), and … are thorough database checks. Flexviews is: lock free for read fully log based supports …
Comment: MySQL Server Memory Usage
September 1, 2006 By 18 Comments
…dealloc_sql’, ’0′ ‘Com_delete‘, ’348788′ ‘Com_delete_multi’, ’1′ ‘Com_…_tables’, ’183240′ ‘Qcache_free_blocks’, ’136′ ‘Qcache_free_memory’, ’10272736′ ‘Qcache_hits’,…mysql.sock pid-file=/var/run/mysql/mysql.pid datadir=/db/disk2/mysql/data log-bin=/var/log/mysql/log log-slow-queries=/var/log/mysql…
Post: Efficient Boolean value storage for Innodb Tables
April 23, 2008 By 6 Comments
…- myisam_data_pointer_size is 6 default plus we need space for delete …) default NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1 mysql> show table status like “%bool%” \G *************************** 1…._length: 11 Data_length: 23068672 Max_data_length: 3096224743817215 Index_length: 1024 Data_free: 0 Auto…
Comment: Finding out largest tables on MySQL Server
October 6, 2008 By 24 Comments
… seem to find records getting deleted anywhere. Can you explain why this is? Here is an example. mysql> select count(*) from table… Rows: 14898977 Avg_row_length: 150 Data_length: 2237661184 Max_data_length: 0 Index_length: 0 Data_free: 0 Auto_increment: NULL Create_time… Rows: 15120698 Avg_row_length: 147 Data_length: 2237661184 Max_data_length: 0 Index_length: 0 Data_free: 0 Auto_increment: NULL Create_time…
Post: MySQL Query Cache
July 27, 2006 By 69 Comments
…Cache” which is quite helpful for MySQL Performance optimization tasks but there… value of Qcache_free_blocks relatively to Qcache_free_memory. FLUSH QUERY… calculate by (Com_insert+Com_delete+Com_update+Com_replace)/Qcache_hits…have multiple copies of the same data in cache effectively wasting memory….
Comment: How to calculate a good InnoDB log file size
December 22, 2008 By 33 Comments
mysql> SHOW GLOBAL VARIABLES LIKE ‘innodb_log_file_size’; …deletes all rows and then repopulates it following by a couple of table scans to manipulate the data…STATUS the stats is: Data_length: 165838848 Index_length: 219807744 Data_free: 0 Comment: InnoDB free: 399360 kB Other things…
