September 21, 2014

How to monitor ALTER TABLE progress in MySQL

While working on a recent support issue as a Percona Support Engineer,  I got one question from a customer asking how to monitor ALTER TABLE progress. Actually, for MySQL 5.5 and prior versions, it’s quite difficult to ALTER the table in a running production environment especially for large tables (with millions records). Because it will rebuild and lock the table […]

How to reclaim space in InnoDB when innodb_file_per_table is ON

When innodb_file_per_table is OFF and all data is going to be stored in ibdata files. If you drop some tables of delete some data then there is no any other way to reclaim that unused disk space except dump/reload method. When Innodb_file_per_table is ON, each table stores data and indexes in it’s own tablespace file. […]

MySQL alternative Percona Server 5.1.68 -14.6 now available

Percona is glad to announce the release of Percona Server  5.1.68 -14.6 on April 19, 2013 (downloads are available here and from the Percona Software Repositories). Based on MySQL 5.1.68, including all the bug fixes in it, Percona Server 5.1.68-14.6, a MySQL alternative, is now the current stable release in the 5.1 series. All of Percona‘s software is open source and free, all the […]

Logging Foreign Key errors

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 […]

Using innodb_sys_tables and innodb_sys_indexes

I was playing with Percona Server today and found fast_index_creation does not work quite exactly like described in the manual. The point I’m looking to make though it would be very hard to catch this problem without additional information_schema tables we added in Percona Server. I was doing simple ALTER TABLE such as: “alter table […]

How to recover a single InnoDB table from a Full Backup

Sometimes we need to restore only some tables from a full backup maybe because your data loss affect a small number of your tables. In this particular scenario is faster to recover single tables than a full backup. This is easy with MyISAM but if your tables are InnoDB the process is a little bit […]

Hijacking Innodb Foreign Keys

I guess I’m first to post in 2012 so Happy New Year all blog readers ! Now back to HardCore MySQL business – foreign Keys. MySQL supported Foreign Keys for Innodb for many years, yet rudimentary support initially added in MySQL 3.23.44 have not been improved in new releases as much as I’d like. We […]

Improved InnoDB fast index creation

One of the serious limitations in the fast index creation feature introduced in the InnoDB plugin is that it only works when indexes are explicitly created using ALTER TABLE or CREATE INDEX. Peter has already blogged about it before, here I’ll just briefly reiterate other cases that might benefit from that feature: when ALTER TABLE […]

Tuning InnoDB Concurrency Tickets

InnoDB has an oft-unused parameter innodb_concurrency_tickets that seems widely misunderstood. From the docs: “The number of threads that can enter InnoDB concurrently is determined by the innodb_thread_concurrency variable. A thread is placed in a queue when it tries to enter InnoDB if the number of threads has already reached the concurrency limit. When a thread […]

How to load large files safely into InnoDB with LOAD DATA INFILE

Recently I had a customer ask me about loading two huge files into InnoDB with LOAD DATA INFILE. The goal was to load this data on many servers without putting it into the binary log. While this is generally a fast way to load data (especially if you disable unique key checks and foreign key […]