June 19, 2013

Post: MySQL Query Patterns, Optimized - Webinar questions followup

June 3, 2013 By 2 Comments

…“MySQL Query Patterns, Optimized” for Percona MySQL Webinars.  If…performance, but it returns a better random choice. Another workaround may be to add a column…’t it be a problem if the keywords …performance! Q: Bill, back to the query where you were trying to determine the last episode of each TV show…

Filed Under: Insight for Developers, MySQL, MySQL Webinars Tagged With: , , ,

Post: Replication in MySQL 5.6: GTIDs benefits and limitations - Part 2

May 30, 2013 By 6 Comments

…show where GTIDs shine and where improvements are expected. This is the second post of a series of articles focused on MySQL… happen when you want to perform a planned failover. With GTIDs,… that this is the same problem for s0 (which will be…4 ? A ‘Last_Executed_GTID’ column would have been useful. In…

Filed Under: Insight for DBAs, MySQL Tagged With: , ,

Post: Percona XtraDB Cluster 5.5.30-23.7.4 for MySQL now available

April 17, 2013 By 2 Comments

… from our repositories. Benchmark showing the impact of memory allocators on MySQL performance can be found in this…would fail in case mixed CHAR and VARCHAR columns would be used in foreign key definitions. Bug…We did our best to eliminate bugs and problems, but this is a software, so bugs are…

Filed Under: MySQL, XtraDB Cluster Tagged With: , ,

Post: The write cache: Swap insanity tome III

April 19, 2013 By 5 Comments

…been something bad for MySQL performance but it is even more important for HA… 3 81 13 0 Note the free column going down and the cache one going… and the write cache was causing the problem. It happened that the setting vm.dirty… of the servers I have access to showed that the common values are 20 and …

Filed Under: Hardware and Storage, Insight for DBAs, MySQL Tagged With: , , ,

Post: Death match! EBS versus SSD price, performance, and QoS

February 21, 2011 By 55 Comments

… of SSDs really a big advantage in practice? I will show the performance of two real customer systems running web applications. Let… so we can see performance throughout the day. If you’re not familiar with the diskstats tool, the columns are the number…. This is causing acute performance problems for the database, manifested as epic stalls and server lockups which show up as sky-high latency…

Filed Under: Cloud and NoSQL, Hardware and Storage, MySQL

Post: A workaround for the performance problems of TEMPTABLE views

May 19, 2010 By 7 Comments

…MySQL sets the ALGORITHM=UNDEFINED, and will chose to use TEMPTABLE when the view is actually used: mysql> show …c1, performance is not good. MySQL is scanning the entire table to produce the result: mysql> select … the value for the connection_id column. Also notice the restriction that v1.c1 …

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Post: InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

March 4, 2013 By 7 Comments

…exactly identical to the same query when performed against InnoDB data, OR that the results…stopword, so does that account for our problem? It might, because the word ‘arizona’ …table with a single VARCHAR column named “value”. OK, sounds easy enough: mysql: SHOW CREATE TABLE innodb_myisam_stopword\G …

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: , , , , ,

Post: Find and remove duplicate indexes

June 20, 2012 By 9 Comments

… the secondary keys contains the primary key column. Let’s see the following example: mysql> show create table t; [...] PRIMARY KEY (`i`), KEY… the problem. Conclusion Indexes are good for our queries but too many indexes or duplicate or redundant indexes can hurt the performance…

Filed Under: Insight for DBAs, Insight for Developers, MySQL, Percona Software

Post: ORDER BY ... LIMIT Performance Optimization

September 1, 2006 By 100 Comments

…MySQL Performance problems. Here is what you need to know about ORDER BY … LIMIT optimization to avoid these problems… sorting is done by leading column(s). Note however columns following column used for order by can… 1 row in set (0.03 sec) See – “rows” is showing us there are estimated 1.6 million…

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Post: InnoDB Full-text Search in MySQL 5.6 (part 1)

February 26, 2013 By 1 Comment

…mysql> show warnings; +———+——+————————————————–+ | Level | Code | Message | +———+——+————————————————–+ | Warning | 124 | InnoDB rebuilding table to add column…

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: , , , , ,
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