by Marcelo Altmann | Oct 28, 2020 | Cloud, Insight for DBAs, MySQL, Percona Software
In a perfect world, we expect all software to run flawlessly and never have problems such as bugs and crashes. We also know that this perfect world doesn’t exist and we better be as prepared as possible to troubleshoot those types of situations. Historically,...
by Marcelo Altmann | Aug 6, 2020 | Insight for DBAs, Insight for Developers, MySQL
At the Percona engineering team, we often receive requests to analyze changes in MySQL/Percona Server for MySQL behavior from one version to another, either due to regression or a bug fix (when having to point out to a customer that commit X has fixed their issue and...
by Avinash Vallarapu | Feb 22, 2019 | PostgreSQL
In case you didn’t already see this news, PostgreSQL has got its first minor version released for 2019. This includes minor version updates for all supported PostgreSQL versions. We have indicated in our previous blog post that PostgreSQL 9.3 had gone EOL, and...
by Sveta Smirnova | Sep 25, 2018 | MySQL
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...
by Roel Van de Paar | Apr 27, 2018 | Insight for DBAs, MySQL, Open Source
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...
by Peter Schwaller | Dec 20, 2017 | MongoDB, MySQL, Percona Events
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...
by Juan Arruti | Feb 8, 2017 | Insight for DBAs, MySQL
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...
by Marcelo Altmann | Jan 27, 2017 | Insight for DBAs, MySQL
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...
by Bill Karwin | Feb 11, 2014 | 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....
by Daniel Nichter | Nov 1, 2013 | MySQL, Percona Software
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...
by Aurimas Mikalauskas | Mar 28, 2011 | Insight for DBAs, MySQL
Have you ever seen BIG weird numbers in mk-query-digest report that just seem wrong? I have! Here’s one report I got today: ... # Attribute total min max avg 95% stddev median # ============ ======= ======= ======= ======= ======= ======= ======= # Exec time...
by Vadim Tkachenko | Nov 29, 2010 | 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...
by Peter Zaitsev | Jun 29, 2010 | 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...
by Maciej Dobrzanski | May 17, 2010 | 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...
by Peter Zaitsev | May 14, 2010 | 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...
by Peter Zaitsev | Feb 15, 2010 | Insight for DBAs, MySQL
As I wrote about 2 years ago the feature of Innodb to store copy of master’s position in Slave’s Innodb tablespace got broken. There is a lot of discussions at the corresponding bug report while outcome of the fix remained uncertain for me (the bug is...
by Morgan Tocker | Jan 9, 2010 | Insight for Developers, MySQL
There was a discussion on LinkedIn one month ago that caught my eye: Database search by “within x number of miles” radius? Anyone out there created a zipcode database and created a “search within x numer of miles” function ? Thankful for any...
by Peter Zaitsev | Dec 5, 2009 | Benchmarks, Insight for DBAs, MySQL
I had an interesting case recently. The customer dealing with large MySQL data warehouse had the table which was had data merged into it with INSERT ON DUPLICATE KEY UPDATE statements. The performance was extremely slow. I turned out it is caused by hundreds of daily...
by Peter Zaitsev | Nov 20, 2009 | Insight for DBAs, MySQL
There is the rare bug which I ran into every so often. Last time I’ve seen it about 3 years ago on MySQL 4.1 and I hoped it is long fixed since… but it looks like it is not. I now get to see MySQL 5.4.2 in the funny state. When you see bug happening you...
by Peter Zaitsev | Jul 18, 2009 | Insight for DBAs
Over last couple of years I have ran into random MySQL crashes in production when multiple key caches were used. Unfortunately this never was frequent or critical enough issue so I could spend time creating repeatable test case and search of the bug in the MySQL...
