September 21, 2014

Quickly finding unused indexes (and estimating their size)

I had a customer recently who needed to reduce their database size on disk quickly without a lot of messy schema redesign and application recoding.  They didn’t want to drop any actual data, and their index usage was fairly high, so we decided to look for unused indexes that could be removed. Collecting data It’s […]

ALTER TABLE: Creating Index by Sort and Buffer Pool Size

Today I was looking at the ALTER TABLE performance with fast index creation and without it with different buffer pool sizes. Results are pretty interesting. I used modified Sysbench table for these tests because original table as initially created only has index on column K which initially contains only zeros, which means index is very […]

Building Indexes by Sorting In Innodb (AKA Fast Index Creation)

Innodb can indexes built by sort since Innodb Plugin for MySQL 5.1 which is a lot faster than building them through insertion, especially for tables much larger than memory and large uncorrelated indexes you might be looking at 10x difference or more. Yet for some reason Innodb team has chosen to use very small (just […]

Innodb vs MySQL index counts

I had a customer recently who a few strange errors in their mysqld.err log:

This customer was running Percona Server 5.1 and they got this error on two tables during a maintenance window when they were adding indexes to the same tables.  We had a suspicion that it had something to do with Fast […]

Improved InnoDB fast index creation

One of the serious limitations in the fast index creation feature introduced in the InnoDB plugin is that it only works when indexes are explicitly created using ALTER TABLE or CREATE INDEX. Peter has already blogged about it before, here I’ll just briefly reiterate other cases that might benefit from that feature: when ALTER TABLE […]

What to do with MySQL Full Text Search while migrating to Innodb ?

It is rather typical for systems to start as MyISAM but as system growths to move to Innodb. The reason of the move could be just desire for better data consistency guaranty or being bitten repairing multiple GB MyISAM table few times, though Table Locks is probably the most important issue – with modern multi […]

MySQL EXPLAIN limits and errors.

Running EXPLAIN for problematic queries is very powerful tool for MySQL Performance optimization. If you’ve been using this tool a lot you probably noticed it is not always provide adequate information. Here is list of things you may wish to watch out. EXPLAIN can be wrong – this does not happen very often but it […]

Multi-Valued INSERTs, AUTO_INCREMENT & Percona XtraDB Cluster

A common migration path from standalone MySQL/Percona Server to a Percona XtraDB Cluster (PXC) environment involves some measure of time where one node in the new cluster has been configured as a slave of the production master that the cluster is slated to replace. In this way, the new cluster acts as a slave of […]

Installing Percona XtraDB Cluster 5.6 with the Docker open-source engine

In my previous post, I blogged about using Percona Server with Docker and have shown you how fast and easy it was to create a virtual environment with just a few commands. This time I will be showing you how to setup a three-node Percona XtraDB Cluster (PXC) 5.6 on the Docker open-source engine. Just […]

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 […]