May 24, 2013

How to recover table structure from InnoDB dictionary

April 22, 2013 By 4 Comments

To recover a dropped or corrupt table with Percona Data Recovery Tool for InnoDB you need two things: media with records(ibdata1, *.ibd, disk image, etc.) and a table structure. Indeed, there is no information about the table structure in an InnoDB page. Normally we either recover the structure from .frm files or take it from [...]

Filed Under: Insight for DBAs, MySQL Tagged With: , , , , , ,

Understanding the maximum number of columns in a MySQL table

April 8, 2013 By 5 Comments

This post was initially going to be two sets of polls: “What is the maximum number of columns in MySQL?” and “What is the minimum maximum number of columns in MySQL?”. Before you read on, ponder those questions and come up with your own answers… and see if you’re right or can prove me wrong! [...]

Filed Under: MySQL Tagged With: , , , , , , , ,

Feature preview: Compact backups in Percona XtraBackup

January 29, 2013 By 11 Comments

We continue to improve Percona XtraBackup, and today I would like to give a preview for one feature which comes in next Percona XtraBackup 2.1 release. This feature is “Compact backups”, and let me explain what it does. As you may know InnoDB PK (Primary Key) contains all data, and all secondary indexes are only [...]

Filed Under: MySQL, Percona Software Tagged With: ,

Sphinx search performance optimization: attribute-based filters

January 15, 2013 By 9 Comments

One of the most common causes of a poor Sphinx search performance I find our customers face is misuse of search filters. In this article I will cover how Sphinx attributes (which are normally used for filtering) work, when they are a good idea to use and what to do when they are not, but [...]

Filed Under: Insight for Developers, MySQL Tagged With: , ,

The Optimization That (Often) Isn’t: Index Merge Intersection

December 14, 2012 By 6 Comments

Prior to version 5.0, MySQL could only use one index per table in a given query without any exceptions; folks that didn’t understand this limitation would often have tables with lots of single-column indexes on columns which commonly appeared in their WHERE clauses, and they’d wonder why the EXPLAIN plan for a given SELECT would [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL

Realtime stats to pay attention to in Percona XtraDB Cluster and Galera

November 26, 2012 By 4 Comments

I learn more and more about Galera every day.  As I learn more, I try to keep my myq_gadgets toolkit up to date with what I consider is important to keep any eye on on a PXC node.  In that spirit, I just today pushed some changes to the ‘wsrep’ report, and I thought I’d go over [...]

Filed Under: MySQL, XtraDB Cluster

Tools and Techniques for Index Design Webinar Questions Followup

October 4, 2012 By 5 Comments

I presented a webinar this week to give an overview of Tools and Techniques for Index Design. Even if you missed the webinar, you can register for it, and you’ll be emailed a link to the recording. I’d like to invite folks who are interested in tools for query optimization to attend the new Percona [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL

Logging Foreign Key errors

September 27, 2012 By Leave a Comment

In the last blog post I wrote about how to log deadlock errors using Percona Toolkit. Foreign key errors have the same problems. InnoDB only logs the last error in the output of SHOW ENGINE INNODB STATUS, so we need another similar tool in order to have historical data. pt-fk-error-logger This is a tool very [...]

Filed Under: MySQL

Hidden columns of query_review_history table

August 28, 2012 By Leave a Comment

You can use pt-query-digest to process a MySQL slow query log and store historical values for review trend analysis into query_review_history table. According to its official documentation you can populate many columns in that table but there are other important ones such as ‘user’, ‘host’, ‘db’ which are not included by default. I will explain [...]

Filed Under: Insight for DBAs, MySQL Tagged With:

MySQL Indexing Best Practices: Webinar Questions Followup

August 16, 2012 By 4 Comments

I had a lot of questions on my MySQL Indexing: Best Practices Webinar (both recording and slides are available now) We had lots of questions. I did not have time to answer some and others are better answered in writing anyway. Q: One developer on our team wants to replace longish (25-30) indexed varchars with [...]

Filed Under: Insight for DBAs, MySQL
« Older Posts