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MySQL super_read_only Bugs

and  | February 8, 2017 |  Posted In: Insight for DBAs, MySQL, Replication

super_read_only

This blog we describe an issue with MySQL 5.7’s super_read_only feature when used alongside with GTID in chained slave instances. Background In MySQL 5.7.5 and onward introduced the gtid_executed table in the MySQL database to store every GTID. This allows slave instances to use the GTID feature regardless whether the binlog option is set or not. Here […]

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When MySQL Lies: Wrong seconds_behind_master with slave_parallel_workers > 0

 | January 27, 2017 |  Posted In: Insight for DBAs, MySQL

super_read_only

In today’s blog, I will show an issue with seconds_behind_master that one of our clients faced when running slave_parallel_workers > 0. We found out that the reported seconds_behind_master from SHOW SLAVE STATUS was lying. To be more specific, I’m talking about bugs #84415 and #1654091. The Issue MySQL will not report the correct slave lag if you have slave_parallel_workers […]

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How Percona Support handles bugs

 | May 11, 2015 |  Posted In: MySQL, Percona MySQL Support

One of the great values of a Percona Support contract is that we provide bug fixes for covered software, and not just support in terms of advice on how to use it. This is the skill which is most likely missing from in-house for most customers, as it requires a team with code knowledge to […]

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WITHer Recursive Queries?

 | February 11, 2014 |  Posted In: Insight for Developers, MySQL

Over the past few years, we’ve seen MySQL technology advance in leaps and bounds, especially when it comes to scalability. But by focusing on the internals of the storage engine for so long, MySQL has fallen behind regarding support for advanced SQL features. SQLite, another popular open-source SQL database, just released version 3.8.3, including support […]

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Quick link to Percona Toolkit bugs

 | November 1, 2013 |  Posted In: MySQL, Percona Software, Percona Toolkit

In this post I wanted to highlight percona.com/bugs/<tool> , for example: percona.com/bugs/pt-stalk.  This only works for Percona Toolkit.  We often advise people to check a tool’s current bugs, but we don’t always say how. The official link for Percona Toolkit bugs on Launchpad is https://bugs.launchpad.net/percona-toolkit/+bugs, but then you still have search from there.  So this quick link […]

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Data Corruption, DRBD and story of bug

 | November 29, 2010 |  Posted In: Hardware and Storage, MySQL

Working with customer, I faced pretty nasty bug, which is actually not rare situation , but in this particular there are some lessons I would like to share. The case is pretty much described in bug 55981, or in pastebin. Everything below is related to InnoDB-plugin/XtraDB, but not to regular InnoDB ( i.e in MySQL […]

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Recall of Percona Server 5.1.47-11.0

 | June 29, 2010 |  Posted In: Percona Software

Percona Server release 11.0 which we announced few days ago unfortunately was released with a bug introduced while implementing stripping comments in query cache which could cause server crash with certain types of queries if query cache is enabled. We have released Percona Server release 11.1 which includes a fix for this issue. If you […]

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Joining on range? Wrong!

 | May 17, 2010 |  Posted In: Insight for Developers, MySQL

The problem I am going to describe is likely to be around since the very beginning of MySQL, however unless you carefully analyse and profile your queries, it might easily go unnoticed. I used it as one of the examples in our talk given at phpDay.it conference last week to demonstrate some pitfalls one may […]

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mysql_upgrade and Innodb Tables

 | May 14, 2010 |  Posted In: Insight for DBAs, MySQL

Upgrading from MySQL 5.0 to MySQL 5.1 or Percona Server 5.1 you may run into issues with mysql_upgrade – it will identify some tables to be upgraded and will attempt to run REPAIR TABLE for them. This will fail with “The storage engine for the table doesn’t support repair” error message. This seems to confuse […]

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