… this as I did not want to risk likehood of execution plans changing for some over queries joining less number of tables… MySQL 5.5 which can produce very expensive plan selections ? Investigating this further I found the following explanation from Timour Katchaounov in MySQL… tables in join I think faster execution plan computation would be more important than backward compatibility. In MySQL 5.6 things are likely…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… both for MariaDB 5.5 and MySQL 5.6, the optimizer chooses the wrong query execution plan. Let’s take a look at… plan ‘b’ for MySQL 5.6 and MariaDB 5.5, then query times remain under a minute. So when the correct query execution plan is not used, there is no difference in query times between MySQL 5.5 and MySQL 5.6/MariaDB…
Post: Percona Live MySQL Conference & Expo Was A Great Event
April 17, 2012 By 2 Comments
… happen. 2013 should be even bigger and better. We planned and executed last week’s event in only a few months, without… Oracle for their new development milestone release for MySQL 5.6, released on Monday. MySQL 5.6 just keeps looking better and… also recorded some of the breakout sessions, so watch Planet MySQL for an announcement when she posts those online. Presentation slides…
Comment: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 22, 2012 By 10 Comments
… execution plans is probably a result of variation in InnoDB statistics. It is not much the Optimizer can do about that. In MySQL 5.6 you can use InnoDB Persistent Statistics to get stable statistics and plan stability. (See http…. (See http://oysteing.blogspot.com/2011/04/more-stable-query-execution-time-by.html)
Post: Percona welcomes Drizzle 7.1
April 10, 2012 By Leave a Comment
… previous stable release, Drizzle 7.0. I plan to write a variety of blog posts… log plugin and auth_schema JS plugin: execute JavaScript code as a Drizzle function HTTP JSON…the Drizzle protocol plugin, authentication from a file, MySQL UNIX socket protocol, javascript plugin, authentication via …
Post: Troubleshooting MySQL Upgrade Performance Regressions
February 15, 2012 By Leave a Comment
… 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 the plan manually to the…
Post: Upgrading MySQL
January 5, 2010 By 23 Comments
…, such as DECIMAL field got whole another meaning in MySQL 5.0 MySQL generally supports legacy storage format for a while, even… you may get queries returning different result or getting different execution plan, taking minutes or hours even though they were previously sub… SELECT queries on both new and old MySQL installations and check result set, explain plan and execution time, reporting you on all the…
Post: Reasons for MySQL Replication Lag
July 29, 2011 By 6 Comments
… can cause serve performance degradation. Configuration Changes Have you changed MySQL configuration ? OS Configuration or Hardware configuration or could have anyone… as increasing buffer pool size could cause performance problems. MySQL Restart MySQL Restarts may include recovery time but what is the most… data which is being accessed by the queries or query execution plans. Side load on IO subsystem Could there be any side…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
…, it reports extra stats such as information about the queries’ execution plan (which includes things like whether Query cache was used or… various data points such as the total query execution time and the average query execution time, the number of tmp tables created… data about the underlying tables involved and the query execution plan used by MySQL. The end result might be that you end up…
Post: MySQL 6.0 vs 5.1 in TPC-H queries
March 25, 2008 By 17 Comments
….1. MySQL 6.0 is interesting here, as there is a lot of new changes in optimizer, which should affect execution plan of TPC-H queries. In reality only two queries (from 22) have significantly better execution time (about them in next posts), but I want to write about is queries that execute slower in new MySQL 6…
