September 2, 2014

State of the art: Galera – synchronous replication for InnoDB

First time I heard about Galera on Percona Performance Conference 2009, Seppo Jaakola was presenting “Galera: Multi-Master Synchronous MySQL Replication Clusters”. It was impressed as I personally always wanted it for InnoDB, but we had it in plans at the bottom of the list, as this is very hard to implement properly. The idea by […]

Is DRBD the right choice for me?

It seems pretty common to find customers install DRBD for the wrong reasons. There are many pros/cons to compare DRBD to replication, but I’ve managed to cut down my spiel I give to customers to these two points: DRBD’s aim (assuming replication mode C) is to provide 100% consistency, and then as much uptime as […]

Why MySQL’s binlog-do-db option is dangerous

I see a lot of people filtering replication with binlog-do-db, binlog-ignore-db, replicate-do-db, and replicate-ignore-db. Although there are uses for these, they are dangerous and in my opinion, they are overused. For many cases, there’s a safer alternative.

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 […]

High-Performance Click Analysis with MySQL

We have a lot of customers who do click analysis, site analytics, search engine marketing, online advertising, user behavior analysis, and many similar types of work.  The first thing these have in common is that they’re generally some kind of loggable event. The next characteristic of a lot of these systems (real or planned) is […]

Thanks Giving Challenge: How to detect replication context

Happy Thanksgiving and little holiday challenge for you. Say you have a trigger on the slave which you would like to work differently, depending on whenever update is executed via replication thread vs updating table locally ? This can be helpful for example for auditing updates which were done directly instead of coming from the […]

Three ways to know when a MySQL slave is about to start lagging

The trouble with slave lag is that you often can’t see it coming. Especially if the slave’s load is pretty uniform, a slave that’s at 90% of its capacity to keep up with the master can be indistinguishable from one that’s at 5% of its capacity. So how can you tell when your slave is […]

Fighting MySQL Replication Lag

The problem of MySQL Replication unable to catch up is quite common in MySQL world and in fact I already wrote about it. There are many aspects of managing mysql replication lag such as using proper hardware and configuring it properly. In this post I will just look at couple of query design mistakes which […]

Recovery beyond data restore

Quite frequently I see customers looking at MySQL recovery as on ability to restore data from backup which can be far from being enough to restore the whole system to operating state, especially for complex systems. Instead of looking just at data restore process you better look at the whole process which is required to […]

Troubleshooting Relay Log Corruption in MySQL

Have you ever seen the replication stopped with message like this: Last_Error: Could not parse relay log event entry. The possible reasons are: the master’s binary log is corrupted (you can check this by running ‘mysqlbinlog’ on the binary log), the slave’s relay log is corrupted (you can check this by running ‘mysqlbinlog’ on the […]