…random index lookups row accesses in the same table) but this is very valuable data point to optimize query…to see (for example as another slow query log record) is the number of rows which MySQL used to generate…think how to fix the situation. For example if you have clause like TITLE LIKE “%MYSQL%” …
Post: Replaying database load with Percona Playback
October 25, 2012 By 9 Comments
…data set or queries. Those tools just run random queries against random generated data. The best way to…In the example I’m going to show how to meassure the impact of my.cnf changes replaying a slow query…
Post: MySQL EXPLAIN limits and errors.
July 24, 2006 By 6 Comments
…generating” step, instead plan is generated as a part of query execution, sometimes being dynamic based on data. With EXPLAIN MySQL…in queries. In general in my opinion EXPLAIN needs serious overhaul so it can be used with GUI tool to…
Post: Fishing with dynamite, brought to you by the randgen and dbqp
November 16, 2011 By Leave a Comment
…to speak highly of the random query generator as a testing tool and thought I would share a story that shows how…in the ‘rows’ section tells the data generator to produce 50 tables, with sizes from 1 row to…
Post: Analyzing air traffic performance with InfoBright and MonetDB
October 2, 2009 By 50 Comments
…to find how to execute command from command line using included sqlline utility, and I did not understand how to do that, so I generated…query in InfoBright. MySQL is really stupid here, and EXPLAIN for this query…
Post: Database access Optimization in Web Applications.
September 12, 2006 By 10 Comments
…to count amount of rows in the table (no joking). Sometimes you would see 100 stories selected so one random…data by single row read. Check number of rows which actually need to be used to generate result sets Sometimes query needs to use many rows to…
Post: How adding another table to JOIN can improve performance ?
August 1, 2008 By 12 Comments
…in huge IN lists and suboptimal execution for large ranges. Lets take a look at very typical reporting query which queries data…to learn about MySQL Optimizer gotchas 
At the same time I figured out how to make MySQL Optimizer to do what we want to…
Post: Cache Miss Storm
September 10, 2010 By 30 Comments
…random arrivals the worse case is worse) which takes 25 seconds to…to generate in case of cache miss. To find first one for memcached you can use mk-query-digest to…to changes to content interest or launch of new features. Use Smarter Cache Especially with memcache it is you who decide how to…
