Tag - Bugs

Why Optimization derived_merge can Break Your Queries

MySQL optimizer bugs

Lately, I worked on several queries which started returning wrong results after upgrading MySQL Server to version 5.7 The reason for the failure was derived merge optimization which is one of the default
optimizer_switch  options. Issues were solved, though at the price of performance, when we turned it
OFF . But, more importantly, we could […]

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MySQL 8.0 GA: Quality or Not?

MySQL 8.0 GA

What does Anton Ego – a fictional restaurant critic from the Pixar movie Ratatouille – have to do with MySQL 8.0 GA?
When it comes to being a software critic, a lot.
In many ways, the work of a software critic is easy. We risk very little and thrive on negative criticism, which is fun to […]

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Updates to Percona Bug Tracking

Percona Bug Tracking

We’re completing our move of Percona bug tracking into JIRA, and the drop-dead date is December 28, 2017.
For some time now, Percona has maintained both the legacy Launchpad bug tracking system and a JIRA bug tracking system for some of the newer products. The time has come to consolidate everything into the JIRA […]

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MySQL super_read_only Bugs

MySQL error code 1215

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 is […]

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When MySQL Lies: Wrong seconds_behind_master with slave_parallel_workers > 0

MySQL error code 1215

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

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 […]

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WITHer Recursive Queries?

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

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

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 5.0)
In […]

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