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Follow these basics when migrating to Percona XtraDB Cluster for MySQL

May 1, 2013 By Jervin Real 9 Comments

Galera/Percona XtraDB Cluster (PXC) for MySQL is a hot thing right now and some users jump right in without enough testing. Consequently, they’re more likely to either suffer failure or issues that prevent them from moving forward. If you are thinking of migrating your workload to Percona XtraDB Cluster, make sure to go through these [...]

Filed Under: Insight for DBAs, MySQL, Percona Software, XtraDB Cluster Tagged With: galera, Jervin Real, Percona XtraDB Cluster, pxc, replicating

InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

March 4, 2013 By Ernie Souhrada 7 Comments

This is part 2 in a 3 part series. In part 1, we took a quick look at some initial configuration of InnoDB full-text search and discovered a little bit of quirky behavior; here, we are going to run some queries and compare the result sets. Our hope is that the one of two things [...]

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

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

Knowing what pt-online-schema-change will do

November 1, 2012 By Daniel Nichter 1 Comment

pt-online-schema-change is simple to use, but internally it is complex. Baron’s webinar about pt-online-schema-change hinted at several of the tool’s complexities. Consequently, users often want to know before making changes what pt-online-schema-change will do when it runs. The tool has two options to help answer this question: –dry-run and –print. When ran with –dry-run and –print, pt-online-schema-change changes nothing [...]

Filed Under: Insight for DBAs, Percona Software Tagged With: pt-online-schema-change

Timezone and pt-table-checksum

September 25, 2012 By Mike Benshoof 1 Comment

I recently worked through an issue with a client trying to detect data drift across some servers that were located in different timezones. Unfortunately, several of the tables had timestamp fields and were set to a default value of CURRENT_TIMESTAMP. From the manual, here is how MySQL handles timezone locality with timestamp fields: Values for TIMESTAMP columns are [...]

Filed Under: Insight for DBAs, MySQL, Percona Software

Recovery after DROP & CREATE

August 22, 2012 By Aleksandr Kuzminsky 1 Comment

In a very popular data loss scenario a table is dropped and empty one is created with the same name. This is because mysqldump in many cases generates the “DROP TABLE” instruction before the “CREATE TABLE”:

DROP TABLE IF EXISTS `actor`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `actor` (
  `actor_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
  `first_name` varchar(45) NOT NULL,
  `last_name` varchar(45) NOT NULL,
  `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`actor_id`),
  KEY `idx_actor_last_name` (`last_name`)
) ENGINE=InnoDB AUTO_INCREMENT=201 DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;

DROP TABLE IF EXISTS `actor`;

/*!40101 SET @saved_cs_client = @@character_set_client */;

/*!40101 SET character_set_client = utf8 */;

CREATE TABLE `actor` (

`actor_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,

`first_name` varchar(45) NOT NULL,

`last_name` varchar(45) NOT NULL,

`last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,

PRIMARY KEY (`actor_id`),

KEY `idx_actor_last_name` (`last_name`)

) ENGINE=InnoDB AUTO_INCREMENT=201 DEFAULT CHARSET=utf8;

/*!40101 SET character_set_client = @saved_cs_client */;

If there were no subsequent CREATE TABLE the recovery would be trivial. Index_id of the PRIMARY index of [...]

Filed Under: MySQL Tagged With: drop table, InnoDB, Recovery

MySQL Indexing Best Practices: Webinar Questions Followup

August 16, 2012 By Peter Zaitsev 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

kernel_mutex problem cont. Or triple your throughput

December 2, 2011 By Vadim Tkachenko 10 Comments

This is to follow up my previous post with kernel_mutex problem. First, I may have an explanation why the performance degrades to significantly and why innodb_sync_spin_loops may fix it. Second, if that is correct ( or not, but we can try anyway), than playing with innodb_thread_concurrency also may help. So I ran some benchmarks with [...]

Filed Under: Benchmarks, MySQL

Avoiding auto-increment holes on InnoDB with INSERT IGNORE

November 29, 2011 By Miguel Angel Nieto 8 Comments

Are you using InnoDB tables on MySQL version 5.1.22 or newer? If so, you probably have gaps in your auto-increment columns. A simple INSERT IGNORE query creates gaps for every ignored insert, but this is undocumented behaviour. This documentation bug is already submitted. Firstly, we will start with a simple question. Why do we have [...]

Filed Under: MySQL

Side load may massively impact your MySQL Performance

November 13, 2011 By Peter Zaitsev 7 Comments

When we’re looking at benchmarks we typically run some stable workload and we run it in isolation – nothing else is happening on the system. This is not however how things happen in real world when we have significant variance in the load and many things can be happening concurrently. It is very typical to [...]

Filed Under: Benchmarks, Insight for DBAs, MySQL

Follow these basics when migrating to Percona XtraDB Cluster for MySQL

InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

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

Knowing what pt-online-schema-change will do

Timezone and pt-table-checksum

Recovery after DROP & CREATE

MySQL Indexing Best Practices: Webinar Questions Followup

kernel_mutex problem cont. Or triple your throughput

Avoiding auto-increment holes on InnoDB with INSERT IGNORE

Side load may massively impact your MySQL Performance

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