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Displaying posts with tag: bugs (reset)
Nasty MySQL Replication Bugs that Affect Upgrade to 5.6

There were two nasty MySQL replication bugs in two different 5.6 releases that would make it difficult to upgrade slaves to MySQL 5.6 while still connected to MySQL 5.5 master. The first of those bugs is MySQL bug 72610 which affects 5.6.19. Essentially this bug is triggered when the table structure on the slave is different from the table structure on the master which leads to unnecessarily large amount of RAM usage while replicating events that affect that table. The amount of RAM used would generally be more noticeable when the replicated transaction consists of thousands of RBR events. The...

The post Nasty MySQL Replication Bugs that Affect Upgrade to 5.6 appeared first on ovais.tariq.

Fun with Bugs #34 - Who has fun to verify your bugs (based on 5.6.21)

This time I decided not just to review all community bugs fixed in recent MySQL 5,6 GA release, 5.6.21, but also to mention who reported them (Morgan does this recently) and, most important for this post - who verified them.

As I've explained long time ago, verification is an important part of a bugs life cycle in MySQL. We need some MySQL engineer to check the bug and make sure there is a repeatable test case for it or it is at least clear what is the real problem behind the report. Bug must be "Verified" (confirmed internally) before developers start to work on the fix.

Usually this engineer is somebody from the bugs verification team where I worked for 7 years. But we later agreed that if a bug is reported by …

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MySQL 5.6.20 on POWER

It’s been a little while since I blogged on MySQL on POWER (last time was thinking that new releases would be much better for running on POWER). Well, I recently grabbed the MySQL 5.6.20 source tarball and had a go with it on a POWER8 system in the lab. There is good news: I now only need one patch to have it function pretty flawlessly (no crashes). Unfortunately, there’s still a bit of an odd thing with some of the InnoDB mutex code (bug filed at some point soon).

But, with this one patch applied, I was getting okay sysbench results and things are looking good.

Now just to hope the MySQL team applies my other patches that improve things on POWER. To be honest, I’m a bit disappointed many of them have sat there for this long… it doesn’t help build a development community when patches can sit for months without either …

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Making MySQL Better More Quickly

With the upcoming release of MySQL 5.7 I begin to see a problem which I think needs attention at least for 5.8 or whatever comes next. The GA release cycle is too long, being about 2 years and that means 3 years between upgrades in a production environment More people use MySQL and the data … Continue reading Making MySQL Better More Quickly

On Dolphins, Panda's and Bugs

MySQL Bugs On Dolphins, Panda's and Bugs

Like any good OpenSource project the MySQL Bugs website is open for anyone to search through. This ofcourse doesn't include the security bugs.

There is a second collection of bugs in the My Oracle Support and these bugs are only accesseble by customers with a support contract. Even when I have access to MOS I still prefer to use the community bugs site. For service requests etc. I would use MOS.

The openness of the bugs database is one of the topic the IOUG MySQL Council discusses with Oracle.

The bugs database has more to offer than just information about initial bugs:

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MariaDB 10 is a Sandbox killjoy?

Using MySQL Sandbox I can install multiple instances of MySQL. It is not uncommon for me to run 5 or 6 instances at once, and in some occasions, I get to have even 10 of them. It is usually not a problem. But today I had an issue while testing MariaDB, for which I needed 5 instances, and I the installation failed after the 4th one. To make sure that the host could run that many servers, I tried installing 10 instances of MySQL 5.6 and 5.7. All at once, for a grand total of 20 instances:

$ make_multiple_sandbox --how_many_nodes=10 5.6.14
installing node 1
installing node 2
installing node 3
installing node 4
installing node 5
installing node 6
installing node 7
installing node 8
installing node 9
installing node 10
group directory installed in $HOME/sandboxes/multi_msb_5_6_14
$ make_multiple_sandbox --how_many_nodes=10 5.7.4 …
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Fun with Bugs #33 - bugs fixed in MySQL 5.6.19

It seems Oracle released MySQL 5.6.19 yesterday. So, it's time to check what community bug reports are fixed there.

Let's start with InnoDB. We have the following bugs fixed:

  • Bug #72079, "Upgrade from 5.6.10 to 5.6.16 crashes and leaves unusable DB". Honestly I had not noted this bug, even though I upgrade several instances on Windows to each and every release since 5.6.8. Probably because I had no need to use FTS indexes till recently...
  • Bug #71014, about two extra memset calls that are now removed. I hope the patch bug report provided was just used.
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Why MySQL engineers open bugs in public bug database?

Oracle engineers suppose to open new bugs in its internal bug database until they think opening them in public one makes sense.

Example of such a case is Bug #68415 "resolveip and mysqlaccess still use gethostbyaddr"

Reason for making it public is that it describes behavior, which was introduced into the tools resolveip and mysqlaccess without intention and they now still can work with NetBIOS name, different or not existent in DNS while MySQL server cannot.

Interesting fact that such NetBIOS names were not ever officially supported, but they worked until deprecated function gethostbyaddr was replaced with recommended to use …

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What's wrong with MySQL Manual

I think that MySQL Manual is one of the reasons why MySQL became and still remains popular. I find a lot of useful information (at least references to share with customers, if not real insights) there even after 9+ years of working with MySQL every day and with all numerous articles and blog posts on most important topics available now. I still have MySQL manual page open at every browser instance on every laptop I use on a regular basis.

It's simply great, well indexed by Google and has meaningful human-readable URLs, so one can even guess them for the topics he need. I have http://dev.mysql.com/doc/refman/5.6/en/merge-storage-engine.html open right now and looking at it I clearly understand without any search that if I need a reference for SELECT syntax in 5.5 I have just replace "5.6" with "5.5" and "merge-storage-engine" with …

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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 for recursive SQL queries using the WITH RECURSIVE syntax, in compliance with SQL:1999.

Why is this significant? It means that MySQL is now the only widely-used SQL implementation that does not support recursive queries. Fifteen years after it was defined in the SQL standard, almost every other SQL database of note has supported this feature:

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