You searched for check changed column - MySQL Performance Blog

MySQL optimizer: ANALYZE TABLE and Waiting for table flush

February 27, 2013 By Miguel Angel Nieto 3 Comments

The MySQL optimizer makes the decision of what execution plan to use based on the information provided by the storage engines. That information is not accurate in some engines like InnoDB and they are based in statistics calculations therefore sometimes some tune is needed. In InnoDB these statistics are calculated automatically, check the following blog [...]

Filed Under: MySQL Tagged With: ANALYZE TABLE, InnoDB, Miguel Angel Nieto, MySQL Optimizer, table flush

InnoDB Full-text Search in MySQL 5.6 (part 1)

February 26, 2013 By Ernie Souhrada 1 Comment

I’ve never been a very big fan of MyISAM; I would argue that in most situations, any possible advantages to using MyISAM are far outweighed by the potential disadvantages and the strengths of InnoDB. However, up until MySQL 5.6, MyISAM was the only storage engine with support for full-text search (FTS). And I’ve encountered many [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: Ernie Souhrada, FTS, FullText Search, InnoDB, MyISAM, MySQL 5.6

Analyzing Slow Query Table in MySQL 5.6

February 18, 2013 By Bill Karwin 1 Comment

Next week I’m teaching an online Percona Training class, called Analyzing SQL Queries with Percona Toolkit. This is a guided tour of best practices for pt-query-digest, the best tool for evaluating where your database response time is being spent. This month we saw the GA release of MySQL 5.6, and I wanted to check if any [...]

Filed Under: Events and Announcements, Insight for DBAs, Live Virtual Training, MySQL, Percona Toolkit, Training Tagged With: Amazon RDS, Bill Karwin, MySQL 5.6, Percona Toolkit, Slow Query Table, SQL, Tips, Training

Implications of Metadata Locking Changes in MySQL 5.5

February 1, 2013 By Ovais Tariq 9 Comments

While most of the talk recently has mostly been around the new changes in MySQL 5.6 (and that is understandable), I have had lately some very interesting cases to deal with, with respect to the Metadata Locking related changes that were introduced in MySQL 5.5.3. It appears that the implications of Metadata Locking have not [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: alter table, ddl, metadata locking, query cache, table cache, transaction, Transaction isolation

Announcing Percona Server 5.1.66-14.2

January 15, 2013 By Hrvoje Matijakovic Leave a Comment

Percona is glad to announce the release of Percona Server 5.1.66-14.2 on January 15th, 2013 (Downloads are available here and from the Percona Software Repositories). Based on MySQL 5.1.66, including all the bug fixes in it, Percona Server 5.1.66-14.2 is now the current stable release in the 5.1 series. All of Percona‘s software is open-source and free, all the details of the release can [...]

Filed Under: Events and Announcements, MySQL, Percona Software Tagged With: Percona Server 5.1.66-14.2

Concatenating MyISAM files

November 19, 2012 By Yves Trudeau 5 Comments

Recently, I found myself involved in the migration of a large read-only InnoDB database to MyISAM (eventually packed). The only issue was that for one of the table, we were talking of 5 TB of data, 23B rows. Not small… I calculated that with something like insert into MyISAM_table… select * from Innodb_table… would take [...]

Filed Under: MySQL

Using pt-table-checksum with Percona XtraDB Cluster

October 15, 2012 By Daniel Nichter 2 Comments

As of Percona Toolkit v2.1.5, pt-table-checksum works correctly with Percona XtraDB Cluster, but it doesn’t work quite like a traditional replication setup because cluster nodes are not like traditional replicas. In this post I demonstrate how to use pt-table-checksum with Percona XtraDB Cluster. First, you’ll need Percona Toolkit v2.1.5 or newer and Percona XtraDB Cluster 5.5.27-23.6 [...]

Filed Under: Insight for DBAs, Percona Software, XtraDB Cluster Tagged With: Percona Toolkit, pt-table-checksum

How to obtain the “LES” (Last Executed Statement) from an Optimized Core Dump?

September 9, 2012 By Roel Van de Paar 9 Comments

Ever ran into a situation where you saw “some important variable you really needed to know about=<optimized out>” while debugging?

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

When is MIN(DATE) != MIN(DATE) ?

September 4, 2012 By Ernie Souhrada 5 Comments

Inspiration for this post is courtesy of a friend and former colleague of mine, Greg Youngblood, who pinged me last week with an interesting MySQL puzzle. He was running Percona Server 5.5.21 with a table structure that looks something like this:

CREATE TABLE foo (
 id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
 uid INT UNSIGNED NOT NULL,
 update_time DATETIME NOT NULL,
 ....
 INDEX `uid` (uid, update_time),
 INDEX `bar` (some_other_columns)
 ....
) ENGINE=InnoDB;

CREATE TABLE foo (

id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,

uid INT UNSIGNED NOT NULL,

update_time DATETIME NOT NULL,

....

INDEX `uid` (uid, update_time),

INDEX `bar` (some_other_columns)

....

) ENGINE=InnoDB;

When he ran this query:

SELECT MIN(update_time) FROM foo WHERE update_time IS NOT NULL AND update_time <> '0000-00-00 00:00:00';

1	SELECT MIN(update_time) FROM foo WHERE update_time IS NOT NULL AND update_time <> '0000-00-00 00:00:00';

The result came back as 2012-06-22 10:28:16. [...]

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

Recovery deleted ibdata1

August 10, 2012 By Aleksandr Kuzminsky 9 Comments

Recently I had a case when a customer deleted the InnoDB main table space – ibdata1 – and redo logs – ib_logfile*. MySQL keeps InnoDB files open all the time. The following recovery technique is based on this fact and it allowed to salvage the database. Actually, the files were deleted long time ago – [...]

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

MySQL optimizer: ANALYZE TABLE and Waiting for table flush

InnoDB Full-text Search in MySQL 5.6 (part 1)

Analyzing Slow Query Table in MySQL 5.6

Implications of Metadata Locking Changes in MySQL 5.5

Announcing Percona Server 5.1.66-14.2

Concatenating MyISAM files

Using pt-table-checksum with Percona XtraDB Cluster

How to obtain the “LES” (Last Executed Statement) from an Optimized Core Dump?

When is MIN(DATE) != MIN(DATE) ?

Recovery deleted ibdata1

Search

Top Searches

Percona Webinars

ABOUT PERCONA

Percona MySQL Training

Percona Careers

SOFTWARE FROM PERCONA

SERVICES FOR MYSQL USERS

ABOUT THIS BLOG AND PERCONA