Search Results for: count of row

Percona Live Amsterdam discounted pricing ends July 26!

The Percona Live Data Performance Conference in Amsterdam is just two months away and it’s going to be an incredible event. With a new expanded focus on MySQL, NoSQL, and Data in the Cloud, this conference will be jam-packed with talks from some of the industry’s leading experts from MongoDB, VMware, Oracle, MariaDB, Facebook, Booking.com, […]

Identifying useful info from MySQL row-based binary logs

As a MySQL DBA/consultant, it is part of my job to decode the MySQL binary logs – and there are a number of reasons for doing that. In this post, I’ll explain how you can get the important information about your write workload using MySQL row-based binary logs and a simple awk script. First, it […]

Looking deeper into InnoDB’s problem with many row versions

A few days ago I wrote about MySQL performance implications of InnoDB isolation modes and I touched briefly upon the bizarre performance regression I found with InnoDB handling a large amount of versions for a single row. Today I wanted to look a bit deeper into the problem, which I also filed as a bug. First […]

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 […]