… MySQL Performance problems. Here is what you need to know about ORDER BY … LIMIT optimization to avoid these problems… * FROM tbl WHERE c=5 ORDER BY a,b limit 10 – In this case first two columns from … 1 row in set (0.03 sec) See – “rows” is showing us there are estimated 1.6 million …
Post: Death match! EBS versus SSD price, performance, and QoS
February 21, 2011 By 54 Comments
…can see performance throughout the day. If you’re not familiar with the diskstats tool, the columns … for example. But the samples I’ll show are from an array of 10 x 100GB EBS volumes… causing acute performance problems for the database, manifested as epic stalls and server lockups which show up as …
Post: Testing MySQL column stores
August 16, 2010 By 15 Comments
… my independent testing from an objective viewpoint. I performed two different types… developing such cases for MySQL column-based storage engines in the… a problem would be “select avg(char_column) from table” where the column … Infobright that would be “show stoppers” for typical OLAP analysis…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
…from in-memory data size and expect gradual performance decrease as database size grows you may be surprised by serve drop in performance…show benefit from using indexes. In fact even MySQL…. “val” column in …problem in MySQL is lack of advanced join methods at this point (the work is on a way) – MySQL…
Post: A workaround for the performance problems of TEMPTABLE views
May 19, 2010 By 7 Comments
… takes a second or two. mysql> show create table t2\G *************************** 1. row *************************** Table:…performance is not good. MySQL is scanning the entire table to produce the result: mysql> select * from… value for the connection_id column. Also notice the restriction that v1….
Post: The story of one MySQL Upgrade
October 8, 2010 By 8 Comments
…MySQL to see what is different in the tables. It turned out one of the float columns stored “-0″ in MySQL… these queries showed some …from Percona Server 5.1 back to MySQL 5.0 and performed…problems you encounter during upgrade are very different depending on the upgrade version – upgrade from MySQL…
Post: How number of columns affects performance ?
September 28, 2009 By 10 Comments
…shows there is surely the problem with dynamic row format table with many columns. But is it because of large number of columns or… mysql [localhost] {msandbox} (test) > select max(t1+0) from t99v1; +———–+ | max(t1+0) | +———–+ | 0 | +———–+ 1 row in set (3.26 sec) mysql [localhost…
Post: Using LoadAvg for Performance Optimization
December 4, 2006 By 4 Comments
…moving average of sum of “r” and “b” columns from VMSTAT. Obviously minimum value for LoadAvg is …are no performance problems, for example if you run single batch job on the server with MySQL, Load Average…reason I would start to worry whatever LoadAvg shows. P.S I acknowledge some of explanations …
Post: Avoiding auto-increment holes on InnoDB with INSERT IGNORE
November 29, 2011 By 7 Comments
… we have gaps on auto-increment columns? Secondly, I will show you a trick to mimic the …and assigns the new value to the column. Prior to MySQL 5.1.22 InnoDB used a …concurrency and performance. The problems are even worse with long running queries like INSERT INTO table1 … SELECT … FROM table2….
Post: Joining on range? Wrong!
May 17, 2010 By 10 Comments
…` and indexes on other columns used in joins. Let’s verify how the query performed in greater detail: SHOW STATUS LIKE ‘Handler_read… can find several bug reports regarding this problem (e.g. #8569, #19548). Some replies from MySQL indicate this may be eventually fixed in…
