Search Results for: hard disk

Explaining Indexes with a Library Metaphor

My favorite metaphor for explaining indexes is comparing them to index cards in an old library. In an old library, you used to (or still do) have index cards at the front desk which have some brief description of the books in the library. They also used to be categorized alphabetically. (image taken from http://www.flickr.com/photos/reedinglessons/2239767394/) […]

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 […]

InnoDB crash recovery speed in MySQL 5.6

It has been a while since I have looked at InnoDB crash recovery. A lot has change in the last few years – we have serious crash recovery performance improvements in MySQL 5.5 and MySQL 5.6, we have solid state drives raising as typical high performance IO subsystem and we also have the ability to […]

Auto-bootstrapping an all-down cluster with Percona XtraDB Cluster

One new feature in Percona XtraDB Cluster (PXC) in recent releases was the inclusion of the ability for an existing cluster to auto-bootstrap after an all-node-down event.  Suppose you lose power on all nodes simultaneously or something else similar happens to your cluster. Traditionally, this meant manually re-bootstrapping the cluster, but not any more. How it […]

Tips from the trenches for over-extended MySQL DBAs

This post is a follow-up to my November 19 webinar, “Tips from the Trenches: A Guide to Preventing Downtime for the Over-Extended DBA,” during which I described some of the most common reasons DBAs experience avoidable downtime. The session was aimed at the “over-stretched DBA,” identified as the MySQL DBA short of time or an […]

Optimizing MySQL for Zabbix

This blog post was inspired by my visit at the annual Zabbix Conference in Riga, Latvia this year, where I gave a couple of talks on MySQL and beyond. It was a two day single-track event with some 200 participants, a number of interesting talks on Zabbix (and related technologies) and really well-organized evening activities. […]

MySQL compression: Compressed and Uncompressed data size

MySQL has information_schema.tables that contain information such as “data_length” or “avg_row_length.” Documentation on this table however is quite poor, making an assumption that those fields are self explanatory – they are not when it comes to tables that employ compression. And this is where inconsistency is born. Lets take a look at the same table […]