Many software developers find they need to store hierarchical data, such as threaded comments, personnel org charts, or nested bill-of-materials. Sometimes it’s tricky to do this in SQL and still run efficient queries against the data. I’ll be presenting a webinar for Percona on February 28 at 9am PST. I’ll describe several solutions for storing [...]
How to Identify Bad Queries in MySQL
January 10, 2011 By 16 Comments
Finding bad queries is a big part of optimization. A scientific optimization process can be simplified to “can anything be improved for less than it costs not to improve it? – if not, we’re done.” In databases, we care most about the work the database is doing. That is, queries. There are other things we [...]
Advanced index analysis with mk-index-usage
November 11, 2010 By 2 Comments
The new release of Maatkit has a useful feature in mk-index-usage to help you determine how indexes are used in more flexible ways. The default report just prints out ALTER statements for removing unused indexes, which is nice, but it’s often helpful to ask more sophisticated questions about index usage. I’ll use this blog’s queries [...]
MySQL Limitations Part 4: One thread per connection
October 27, 2010 By 14 Comments
This is the third in a series on what’s seriously limiting MySQL in core use cases (links: part 1, 2, 3). This post is about the way MySQL handles connections, allocating one thread per connection to the server.
Recall of Percona Server 5.1.47-11.0
June 29, 2010 By 10 Comments
Percona Server release 11.0 which we announced few days ago unfortunately was released with a bug introduced while implementing stripping comments in query cache which could cause server crash with certain types of queries if query cache is enabled. We have released Percona Server release 11.1 which includes a fix for this issue. If you [...]
On Good Instrumentation
May 31, 2010 By 1 Comment
In so many cases troubleshooting applications I keep thinking how much more efficient things could be going if only there would be a good instrumentation available. Most of applications out there have very little code to help understand what is going on and if it is there it is frequently looking at some metrics which [...]
Star Schema Bechmark: InfoBright, InfiniDB and LucidDB
January 7, 2010 By 48 Comments
In my previous rounds with DataWarehouse oriented engines I used single table without joins, and with small (as for DW) datasize (see http://www.mysqlperformanceblog.com/2009/10/02/analyzing-air-traffic-performance-with-infobright-and-monetdb/, http://www.mysqlperformanceblog.com/2009/10/26/air-traffic-queries-in-luciddb/, http://www.mysqlperformanceblog.com/2009/11/02/air-traffic-queries-in-infinidb-early-alpha/). Addressing these issues, I took Star Schema Benchmark, which is TPC-H modification, and tried run queries against InfoBright, InfiniDB, LucidDB and MonetDB. I did not get results for MonetDB, will [...]
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 [...]
A few administrative updates
August 26, 2009 By 12 Comments
I wanted to write a few administrative updates in one so I didn’t spam everyone’s feed readers too much. Here we go: We’ve had reports of some lost comments. Â We reported this via Twitter a while ago, but thought it was fixed. Â We’ll try and pay more attention to spam filtering, but we wanted to [...]
mk-query-digest, query comments and the query cache
I very much like the fact that MySQL allows you to embed comments into SQL statements. These comments are extremely convenient, because they are written into MySQL log files as part of the query. This includes the general log, the binary log and the slow query log. Maatkit includes tools which interact with these logs, [...]