April 18, 2014

About Jervin Real

Jervin is a member of Percona's Rapid Response Consulting team. When you come to Percona for consulting, chances are he'll be greeting you first. His primary role is to make sure customer issues are handled efficiently and professionally. Jervin joined Percona in May 2010.

keepalived with reader and writer VIPs for Percona XtraDB Cluster

This is a followup to Jay Janssen’s October post, “Using keepalived for HA on top of Percona XtraDB Cluster.” We got a request recently where the customer has 2 VIPs (Virtual IP addresses), one for reader and one for a writer for a cluster of 3 nodes. They wanted to keep it simple, with low […]

One more InnoDB gap lock to avoid

While troubleshooting deadlocks for a customer, I came around an interesting situation involving InnoDB gap locks. For a non-INSERT write operation where the WHERE clause does not match any row, I expected there should’ve been no locks to be held by the transaction, but I was wrong. Let’s take a look at this table and […]

utf8 data on latin1 tables: converting to utf8 without downtime or double encoding

Here’s a problem some or most of us have encountered. You have a latin1 table defined like below, and your application is storing utf8 data to the column on a latin1 connection. Obviously, double encoding occurs. Now your development team decided to use utf8 everywhere, but during the process you can only have as little […]

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 […]

Follow these basics when migrating to Percona XtraDB Cluster for MySQL

Galera/Percona XtraDB Cluster (PXC) for MySQL is a hot thing right now and some users jump right in without enough testing. Consequently, they’re more likely to either suffer failure or issues that prevent them from moving forward. If you are thinking of migrating your workload to Percona XtraDB Cluster, make sure to go through these […]

Distro Packages, Pre-built Binaries or Compile Your Own MySQL

I’ve been helping customers deploy and maintain MySQL (and variants) for the last couple of years and it has always been interesting to hear customer thoughts on how they want their servers installed. It has also been asked many times not only by our support and consulting customers, but widely from different forums and blogs […]

Faster Point In Time Recovery with LVM2 Snaphots and Binary Logs

LVM snapshots is one powerful way of taking a consistent backup of your MySQL databases – but did you know that you can now restore directly from a snapshot (and binary logs for point in time recovery) in case of that ‘Oops’ moment? Let me show you quickly how. This howto assumes that you already […]

STOP: DELETE IGNORE on Tables with Foreign Keys Can Break Replication

DELETE IGNORE suppresses errors and downgrades them as warnings, if you are not aware how IGNORE behaves on tables with FOREIGN KEYs, you could be in for a surprise. Let’s take a table with data as example, column c1 on table t2 references column c1 on table t1 – both columns have identical set of rows for […]

How To Test Your Upgrades – pt-upgrade

Upgrades are usually one of the biggest part of any database infrastructure maintenance. Even with enough planning something else can go bad after sending your production application to the version you’ve upgraded to. Let’s look at how one Percona Toolkit tool, pt-upgrade can help you identify what to expect and test your upgrades better which […]

When Does InnoDB Update Table Statistics? (And When It Can Bite)

An InnoDB table statistics is used for JOIN optimizations and helping the MySQL optimizer choose the appropriate index for a query. If a table’s statistics or index cardinality becomes outdated, you might see queries which previously performed well suddenly show up on slow query log until InnoDB again updates the statistics. But when does InnoDB […]