… configuration options in case you get lucky. Sometimes you do but more often you just waste your time. Instead try to understand… between MySQL Server versions you should: Check Query Plan Run EXPLAIN to see if plans for the query are the same. Changing Query Execution plans is the most common regression problem. If plan has changed check if you can get…
Post: Scaling problems still exist in MySQL 5.5 and Percona Server 5.5
May 20, 2011 By 11 Comments
…the application by aggregating query log with mk-query-digest. When I filtered out only queries of this … 5.5 showing up to 2.5 times better performance or 150%, which is a …get_next,rr_quick,sub_select,do_select,JOIN::exec,mysql_sel ect,handle_select,execute_sqlcom_select,mysql_execute_command,mysql…
Post: Checking for a live database connection considered harmful
May 5, 2010 By 38 Comments
…MySQL protocol level, which will increment Com_admin_commands in SHOW GLOBAL STATUS, or a trivial query… network round-trip plus the query execution time, and the added load on …queries are long, the extra query is lost in the noise. But high-traffic apps put tremendous effort into getting query times…
Post: MySQL 5.6.10 Optimizer Limitations: Index Condition Pushdown
March 14, 2013 By 2 Comments
… ‘Jaime’ somewhere in the field note. The original query had a stable execution time of 1.09 sec, while the following one, which… of execution time, probably its cost has to be tuned better in the feature. There are more ways to make a query faster… to be prepared for the MySQL 5.6 release, and get advantage of the latest integrated tools that MySQL provides with its last…
Post: Upgrading MySQL
January 5, 2010 By 24 Comments
…work differently after change. For example you may get queries returning different result or getting different execution plan, taking minutes or hours even …tool will run SELECT queries on both new and old MySQL installations and check result set, explain plan and execution time, reporting you on…
Post: How to Identify Bad Queries in MySQL
January 10, 2011 By 16 Comments
…queries or groups of queries that add too much load to the system by grouping queries into classes and summing the execution time…query executed, not merely the duration the query executed for, which has been available in MySQL…
Post: MySQL Slow query log in the table
May 31, 2007 By 1 Comment
As of MySQL 5.1 get MySQL slow query log logged in mysql.slow_log table instead of the file as you had … TIME type which is used to store query execution time and lock time does not store fractions of the second. Today I’ve got some time to play with table based slow query…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
… has 100 byte rows. With decent SCSI drive we can get 100MB/sec read speed which gives us about 1.000… sets. In MySQL single query runs as single thread (with exeption of MySQL Cluster) and MySQL issues IO requests one by one for query execution, which means if single query execution time…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
…The MySQL command line client was used to execute the a script file containing the 11 queries. … queries, followed by a response time table recording the actual response times for each query. The queries …get Shard-Query (currently in development release form as a checkout from SVN) here: Shard-Query …
Post: MySQL Upgrade Webinar Questions Followup
June 28, 2012 By 7 Comments
… data. Q: What to do if Query Execution Plan changes for the worst during Upgrade… to get to old execution plans. In many cases though you can get to former execution …time so other has full resources (including memory) available. Another thing to mention having multiple instances of different MySQL…
