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Dealing with corrupted InnoDB data

 | January 19, 2016 |  Posted In: MySQL

Data corruption! It can happen. Maybe because of a bug or storage problem that you didn’t expect, or MySQL crashes when a page checksum’s result is different from what it expected. Either way, corrupted data can and does occur. What do you do then? Let’s look at the following example and see what can be […]

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pt-online-schema-change and innodb_stats_persistent on MySQL 5.6

 | November 13, 2015 |  Posted In: MySQL

pt-stalk

Recently we released an updated version of our Percona Toolkit with an important update for pt-online-schema-change if you use MySQL 5.6. A new parameter has been added, analyze-before-swap. What does it do? Let me explain it in more detail. A bug not a bug A customer contacted us because pt-online-schema-change caused hundred of queries to […]

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Find unused indexes on MongoDB and TokuMX

 | August 21, 2015 |  Posted In: MongoDB

Finding and removing unused indexes is a pretty common technique to improve overall performance of relational databases. Less indexes means faster insert and updates but also less disk space used. The usual way to do it is to log all queries’ execution plans and then get a list of those indexes that are not used. […]

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Checking table definition consistency with mysqldiff

 | April 15, 2015 |  Posted In: MySQL

Data inconsistencies in replication environments are a pretty common. There are lots of posts that explain how to fix those using pt-table-checksum and pt-table-sync. Usually we only care about the data but from time to time we receive this question in support: How can I check the table definition consistency between servers? Replication also allow […]

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Sys Schema for MySQL 5.6 and MySQL 5.7

 | November 20, 2014 |  Posted In: Insight for DBAs, MySQL

Performance Schema (P_S) has been available since MySQL 5.5, more than 4 years ago. It is still difficult to see production servers with P_S enabled, even with MySQL 5.6 where the feature is enabled by default. There have been several complaints like the overhead, that the fix is a work in progress, and the ease […]

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How to calculate the correct size of Percona XtraDB Cluster’s gcache

 | September 8, 2014 |  Posted In: Insight for DBAs, MySQL, Percona MySQL Support, Percona Software, Percona XtraDB Cluster

When a write query is sent to Percona XtraDB Cluster all the nodes store the writeset on a file called gcache. By default the name of that file is galera.cache and it is stored in the MySQL datadir. This is a very important file, and as usual with the most important variables in MySQL, the […]

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How to add an existing Percona XtraDB Cluster to Percona ClusterControl

 | April 1, 2014 |  Posted In: Insight for DBAs, MySQL, Percona XtraDB Cluster

In my last blog post I explained how to use Percona ClusterControl to create a new Percona XtraDB Cluster from scratch. That’s a good option when you want to create a testing environment in just some mouse clicks. In this case I’m going to show you how to add your existing cluster to Percona ClusterControl […]

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