Search Results for: select from group by

Faster MySQL failover with SELECT mirroring

One of my favorite MySQL configurations for high availability is master-master replication, which is just like normal master-slave replication except that you can fail over in both directions. Aside from MySQL Cluster, which is more special-purpose, this is probably the best general-purpose way to get fast failover and a bunch of other benefits (non-blocking ALTER […]

Speeding up GROUP BY if you want aproximate results

Doing performance analyzes today I wanted to count how many hits come to the pages which get more than couple of visits per day. We had SQL logs in the database so It was pretty simple query:

Unfortunately this query ran for over half an hour badly overloaded server and I had to kill […]

Using GROUP BY WITH ROLLUP for Reporting Performance Optimization

Quite typical query for reporting applications is to find top X values. If you analyze Web Site logs you would look at most popular web pages or search engine keywords which bring you most of the traffic. If you’re looking at ecommerce reporting you may be interested in best selling product or top sales people. […]

Measuring the impact of tcpdump on Very Busy Hosts

A few years back Deva wrote about how to use tcpdump on very busy hosts. That post sparked my interest about exploring how to measure the impact of tcpdump on very busy hosts. In this post, I wanted to highlight how much of an impact there really is and what options you have to make the […]

Free MySQL QA & Bash/Linux Training Series

Welcome to the MySQL QA Training Series! If you have not read our introductory blog post on pquery yet, I’d recommend reading that one first to get a bit of background. The community is enthuastic about pquery, and today I am happy to announce a full training series on pquery and more. Whether you are […]

Advanced JSON for MySQL

What is JSON JSON is an text based, human readable format for transmitting data between systems, for serializing objects and for storing document store data for documents that have different attributes/schema for each document. Popular document store databases use JSON (and the related BSON) for storing and transmitting data. Problems with JSON in MySQL It […]