July 23, 2014

3 ways MySQL uses indexes

I often see people confuse different ways MySQL can use indexing, getting wrong ideas on what query performance they should expect. There are 3 main ways how MySQL can use the indexes for query execution, which are not mutually exclusive, in fact some queries will use indexes for all 3 purposes listed here.

Performance gotcha of MySQL memory tables

One performance gotcha with MEMORY tables you might know about comes from the fact it is the only MySQL storage engine which defaults to HASH index type by default, instead of BTREE which makes indexes unusable for prefix matches or range lookups. This is however not performance gotcha I’m going to write about. There is […]

MySQL Users Conference – Innodb

It might look like it is too late to write about stuff happened at Users Conference but I’m just starting find bits of time from processing accumulated backlog. The Theme of this Users Conference was surely Storage Engines both looking at number of third party storage engine presented, main marketing message – Storage Engine partnership […]

Getting MySQL to use full key length

There is one bug, or “missing feature” in MySQL Optimizer which may give you hard time causing performance problems which may be hard to track down, it is using only part of the index when full index can be used or using shorter index while there is longer index available. The last item is yet […]

Covering index and prefix indexes

I already wrote in the blog as well mentioned in presentation there is often a choice you have to make between having prefix index – which can be significantly smaller in size and having index being covering index, which means query can be executed using only data from the index without reading the row itself. […]

Duplicate indexes and redundant indexes

About every second application I look at has some tables which have redundant or duplicate indexes so its the time to speak about these a bit. So what is duplicate index ? This is when table has multiple indexes defined on the same columns. Sometimes it is indexes with different names, sometimes it is different […]

MySQL Server Variables – SQL layer or Storage Engine specific.

MySQL Server has tons of variables which may be adjusted to change behavior or for performance purposes. They are documented in the manual as well as on new page Jay has created. Still I see constant confusion out where which of variables apply to storage engines only and which are used on SQL layer and […]

A technical WebScaleSQL review and comparison with Percona Server

The recent WebScaleSQL announcement has made quite a splash in the MySQL community over the last few weeks, and with a good reason. The collaboration between the major MySQL-at-scale users to develop a single code branch that addresses the needs of, well, web scale, is going to benefit the whole community. But I feel that […]

Percona XtraDB Cluster 5.5.34-25.9 is now available

Percona is glad to announce the release of Percona XtraDB Cluster 5.5.34-25.9 on December 4, 2013. Binaries are available from the downloads area or from our software repositories. Based on Percona Server 5.5.34-32.0 including all the bug fixes in it, Galera Replicator and on Codership wsrep API 5.5.34-25.9, Percona XtraDB Cluster 5.5.34-25.9 is now the […]

Percona XtraDB Cluster 5.6.14-25.1 Beta is now available

Percona is glad to announce the first Beta release of Percona XtraDB Cluster 5.6 on November 21st, 2013. Binaries are available from downloads area or from our software repositories. Based on Percona Server 5.6.14-62.0 including all the bug fixes in it, Galera Replicator 3.1 and on Codership wsrep API 5.6.14-25.1 is now the first BETA […]