September 1, 2014

Using Sphinx as MySQL data retrieval accelerator

I’ve run into the following thread couple of days ago: Basically someone is using sphinx to perform search simply on attributes (date, group etc) and get sorted result set and claiming it is way faster than getting it with MySQL. Honestly I can well believe it for cases when you want to know number of […]

Wrong GROUP BY makes your queries fragile

This is probably well known issue for everyone having some MySQL experience or experience with any other SQL database. Still I see this problem in many production applications so it is worth to mention it, especially as it is connected to MySQL Performance. No it might not affect MySQL Performance per say but it limits […]

Descending indexing and loose index scan

Comments to my previous posts, especially this one by Gokhan inspired me to write a bit about descending indexes and about loose index scan, or what Gokhan calls “better range” support. None of these are actially related to Innodb tables in general – these are features MySQL should get for all storage engines at some […]

Do not trust vmstat IOwait numbers

I’ve been running a benchmark today on my old test box with conventional hard drives (no raid with BBU) and noticed something unusual in the CPU utilization statistics being reported. The benchmark was run like this:

Which means: create 64 threads and hammer the database with queries as quickly as possible. As the test […]

Parallel Query for MySQL with Shard-Query

While Shard-Query can work over multiple nodes, this blog post focuses on using Shard-Query with a single node.  Shard-Query can add parallelism to queries which use partitioned tables.  Very large tables can often be partitioned fairly easily. Shard-Query can leverage partitioning to add paralellism, because each partition can be queried independently. Because MySQL 5.6 supports the […]

Introducing backup locks in Percona Server

TL;DR version: The backup locks feature introduced in Percona Server 5.6.16-64.0 is a lightweight alternative to FLUSH TABLES WITH READ LOCK and can be used to take both physical and logical backups with less downtime on busy servers. To employ the feature with mysqldump, use mysqldump –lock-for-backup –single-transaction. The next release of Percona XtraBackup will […]

How to monitor ALTER TABLE progress in MySQL

While working on a recent support issue as a Percona Support Engineer,  I got one question from a customer asking how to monitor ALTER TABLE progress. Actually, for MySQL 5.5 and prior versions, it’s quite difficult to ALTER the table in a running production environment especially for large tables (with millions records). Because it will rebuild and lock the table […]

8 common (but deadly) MySQL operations mistakes and how to avoid them

January 22 I gave a presentation on “How to Avoid Common (but Deadly) MySQL Operations Mistakes” for Percona MySQL Webinars. If you missed it, you can still register to view the recording and my slides. Thanks to everyone who attended, and especially to folks who asked the great questions. I answered as many as we […]

Calvin Sun on MySQL at Twitter, Percona Live 2014 and Facebook

Twitter’s Calvin Sun (@Calvinsun2012) is looking forward to the fast-approaching Percona Live MySQL Conference and Expo this April 1-4 in Santa Clara, Calif. He’ll be speaking, yes, but he’s also looking forward to learning from his peers – particularly those at Facebook. Both companies, he explained, are in the rather unique positions of unprecedented rapid […]

MySQL encryption performance, revisited

This is part two on a two-part series on the performance implications of in-flight data encryption with MySQL. In the first part, I focused specifically on the impact of using MySQL’s built-in SSL support with some rather surprising results. Certainly it was expected that query throughput would be lower with SSL than without, but I […]