October 24, 2014

Percona Live NY 2012 Super Saver discounts end tomorrow. Book Now!

If you’re looking for best prices for Percona Live NY 2012, taking place Oct 1,2 in New York do not delay and book now. Super Saver discounts ends tomorrow, which can save you hundreds of dollars off conference prices list prices. These are the best prices you can get by booking early – There will […]

Explosive OpenStack growth at the Percona Live MySQL Conference & Expo

The Percona Live MySQL Conference and Expo 2014 runs April 1-4  at the Santa Clara Convention Center and Santa Clara Hyatt – but be sure to get there a day early for the inaugural Open Source Appreciation Day on March 31 – this event is free but because space is limited I suggest registering now to […]

How rows_sent can be more than rows_examined?

When looking at queries that are candidates for optimization I often recommend that people look at rows_sent and rows_examined values as available in the slow query log (as well as some other places). If rows_examined is by far larger than rows_sent, say 100 larger, then the query is a great candidate for optimization. Optimization could […]

Another reason why SQL_SLAVE_SKIP_COUNTER is bad in MySQL

It is everywhere in the world of MySQL that if your replication is broken because an event caused a duplicate key or a row was not found and it cannot be updated or deleted, then you can use ‘ STOP SLAVE; SET GLOBAL SQL_SLAVE_SKIP_COUNTER=1; START SLAVE; ‘ and be done with it. In some cases this is fine and you can repair the […]

MySQL Wish for 2013 – Better Memory Accounting

With Performance Schema improvements in MySQL 5.6 I think we’re in the good shape with insight on what is causing performance bottlenecks as well as where CPU resources are spent. (Performance Schema does not accounts CPU usage directly but it is something which can be relatively easily derived from wait and stage information). Where we’re […]

Last chance for a discount on Percona Live DC!

In just over a week, we’ll be running a Percona Live MySQL conference in the nation’s capital, in a beautiful modern conference facility that has its own Metro rail stop. And for a limited time, you can save 20% with this discount code: PerLiveDC. If you’re in the DC area and you use MySQL, this […]

Innodb row size limitation

I recently worked on a customer case where at seemingly random times, inserts would fail with Innodb error 139. This is a rather simple problem, but due to it’s nature, it may only affect you after you already have a system running in production for a while.

Debugging problems with row based replication

MySQL 5.1 introduces row based binary logging. In fact, the default binary logging format in GA versions of MySQL 5.1 is ‘MIXED’ STATEMENT*;   The binlog_format  variable can still be changed per sessions which means it is possible that some of your binary log entries will be written in a row-based fashion instead of the […]

A common problem when optimizing COUNT()

When optimizing queries for customers, the first thing I do with a slow query is figure out what it’s trying to do. You can’t fully optimize a query unless you know how to consider alternative ways to write it, and you can’t do that unless you know what the query “means.” I frequently run into […]

Missing Data – rows used to generate result set

As Baron writes it is not the number of rows returned by the query but number of rows accessed by the query will most likely be defining query performance. Of course not all row accessed are created equal (such as full table scan row accesses may be much faster than random index lookups row accesses […]