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A Second Rule of Thumb for Choosing Column Order in Indexes

A couple of weeks ago, Baron Schwartz wrote an interesting post describing a rule of thumb he sometimes uses to choose the order of columns in an index. In a nutshell, he recommends putting highly …


ORDER BY … LIMIT Performance Optimization

Suboptimal ORDER BY implementation, especially together with LIMIT is often the cause of MySQL Performance problems. Here is what you need to know about ORDER BY … LIMIT optimization to avoid these problems ORDER BY …


Update on the InnoDB double-write buffer and EXT4 transactions

In a post, written a few months ago, I found that using EXT4 transactions with the “data=journal” mount option, improves the write performance significantly, by 55%, without putting data at risk. Many people commented on …


MaxScale: A new tool to solve your MySQL scalability problems

Ever since MySQL replication has existed, people have dreamed of a good solution to automatically split read from write operations, sending the writes to the MySQL master and load balancing the reads over a set …


Profiling MySQL queries from Performance Schema

When optimizing queries and investigating performance issues, MySQL comes with built in support for profiling queries aka SET profiling = 1; . This is already awesome and simple to use, but why the PERFORMANCE_SCHEMA alternative? Because profiling will be …


Yelp IT! A talk with 3 Yelp MySQL DBAs on Percona Live & more

Founded in 2004 to help people find great local businesses, Yelp has some 135 million monthly unique visitors. With those traffic volumes Yelp’s 300+ engineers are constantly working to keep things moving smoothly – and …


Free MySQL QA & Bash/Linux Training Series

Welcome to the MySQL QA Training Series! If you have not read our introductory blog post on pquery yet, I’d recommend reading that one first to get a bit of background. The community is enthuastic …


Deep dive into MySQL’s innochecksum tool

One of our Percona Support customers recently reported that Percona XtraBackup failed with a page corruption error on an InnoDB table. The customer thought it was a problem or bug in the Percona XtraBackup tool. …


Advanced JSON for MySQL

What is JSON JSON is an text based, human readable format for transmitting data between systems, for serializing objects and for storing document store data for documents that have different attributes/schema for each document. Popular …


‘Indexing’ JSON documents for efficient MySQL queries over JSON data

MySQL meets NoSQL with JSON UDF I recently got back from FOSDEM, in Brussels, Belgium. While I was there I got to see a great talk by Sveta Smirnova, about her MySQL 5.7 Labs release …