Combating “data drift” In my first post in this series, I described materialized views (MVs). An MV is essentially a cached result set at one point in time. The contents of the MV will become incorrect (out of sync) when the underlying data changes. This loss of synchronization is sometimes called drift. This is conceptually [...]
Flexviews – part 3 – improving query performance using materialized views
April 4, 2011 By 20 Comments
Using Flexviews – part two, change data capture
March 25, 2011 By 26 Comments
In my previous post I introduced materialized view concepts. This post begins with an introduction to change data capture technology and describes some of the ways in which it can be leveraged for your benefit. This is followed by a description of FlexCDC, the change data capture tool included with Flexviews. It continues with an [...]
Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
I am constantly referring to the amazing MySQL manual, especially the option and variable reference table. But just as frequently, I want to look up blog posts on variables, or look for content in the Percona documentation or forums. So I present to you what is now my newest Firefox toolbar bookmark: an option and [...]
Reasons for run-away main Innodb Tablespace
June 10, 2010 By 2 Comments
So you’re running MySQL With innodb_file_per_table option but your ibdata1 file which holds main (or system) tablespace have grown dramatically from its starting 10MB size. What could be the reason of this growth and what you can do about it ? There are few things which are always stored in main tablespace – these are [...]
Tuning InnoDB Concurrency Tickets
May 24, 2010 By 5 Comments
InnoDB has an oft-unused parameter innodb_concurrency_tickets that seems widely misunderstood. From the docs: “The number of threads that can enter InnoDB concurrently is determined by the innodb_thread_concurrency variable. A thread is placed in a queue when it tries to enter InnoDB if the number of threads has already reached the concurrency limit. When a thread [...]
Analyzing air traffic performance with InfoBright and MonetDB
October 2, 2009 By 50 Comments
Accidentally me and Baron played with InfoBright (see http://www.mysqlperformanceblog.com/2009/09/29/quick-comparison-of-myisam-infobright-and-monetdb/) this week. And following Baron’s example I also run the same load against MonetDB. Reading comments to Baron’s post I tied to load the same data to LucidDB, but I was not successful in this. I tried to analyze a bigger dataset and I took public [...]
Maatkit Now Supports Memcached
July 24, 2009 By 11 Comments
Have you ever wondered how optimized your Memcached installation is? There is a common misconception that one doesn’t have to think too deeply about Memcached performance, but that is not true. If your setup is inefficient, you could: Burn Memory Waste Network Round-Trips Store Keys That Never Get Retrieved Have a Low Cache Hit Ratio [...]
Slow DROP TABLE
June 16, 2009 By 21 Comments
It is a known fact that ext3 is not the most efficient file system out there and for example file removals can be painfully slow and cause a lot of random I/O. However, as it turns out, it can sometimes have a much more severe impact on the MySQL performance that it would seem. When [...]
Limiting InnoDB Data Dictionary
February 11, 2009 By 13 Comments
One of InnoDB’s features is that memory allocated for internal tables definitions is not limited and may grow indefinitely. You may not notice it if you have an usual application with say 100-1000 tables. But for hosting providers and for user oriented applications ( each user has dedicated database / table) it is disaster. For [...]
Poor man’s query logging
November 7, 2008 By 5 Comments
Occasionally there is a need to see what queries reach MySQL. The database provides several ways to share that information with you. One is called general log activated with
1 | --log |
(or
1 | --general-log |
in MySQL 5.1+) start-up parameter. The log writes any query being executed by MySQL to a file with limited amount of additional information. [...]
