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Fun with Bugs #65 - On MySQL Bug Reports I am Subscribed to, Part V

I think it's time to review some bugs I've subscribed to several months ago, those older than in the first post from this series. There are several really serious bugs in the list of 15 below:

  • Bug #87560 - "XA PREPARE log order error in replication and binlog recovery". This bug was reported by Wei Zhao, who also provided patches.
  • Bug #87526 - "The output of 'XA recover convert xid' is not useful". This bug reported by Sveta Smirnova is well known and is a real pain for DBAs who have to deal with incomplete XA transactions after some crash or unexpected restart. Check  …
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Fun with Bugs #63 - On Bugs Detected by ASan

Among other things Geir Hoydalsvik stated in his nice post yesterday:
 "We’ve fixed a number of bugs detected by UBsan and Asan." This is indeed true, I already noted many related bugs fixed in recent MySQL 8.0.4. But I think that a couple of details are missing in the blog post. First of all, there still a notable number of bugs detected by ASan or noted in builds with ASan that remain "Verified". Second, who actually found and reported these bugs?

I decided to do a quick search and present my summary to clarify these details. Let me start with the list of "Verified" or "Open" bugs in public MySQL bugs database, starting from the oldest one:

  • Bug #69715 - "UBSAN: Item_func_mul::int_op() mishandles …
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MySQL security for real users


Security features overview

One of Oracle's tenets is the focus on security. For this reason, when it took over the stewardship of MySQL, it started addressing the most common issues. It was not quick acting, but we have seen real progress:

  1. MySQL 5.7 has removed the anonymous accounts, which was the greatest threat to security. Because of those accounts, and the default privileges granted to them, users without any privileges could access the "test" database and do serious damage. Additionally, because of the way the privilege engine evaluates accounts, anonymous users could hijack legitimate users, by preventing them to work properly.
  2. The "root" account now comes with a password defined during …
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Fun with Bugs #59 - On MySQL Bug Reports I am Subscribed to, Part II

New Year (that starts on Monday!) gives a good opportunity to change something in our lives, start doing something new, better or different. Let's assume I failed with all these so far, as I am again posting about MySQL bugs here.

Since my previous post on this topic I've subscribed to 15 more MySQL bugs, and being on a combination of public holidays and vacation now gives me a good opportunity to review these bug reports.

Here they are, starting from the most recent:

  • Bug #89065 - "sync_binlog=1 on a busy server and slow binary log filesystem stalls slaves". I do not remember seeing multiple threads in "Finished reading one binlog; switching to next binlog" state, but it would be …
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How to Find Processlist Thread id in gdb

I was involved in a discussion on some complex MySQL-related problem where we had to study backtraces of all threads in gdb (produced by the thread apply all bt command if you ever forgets this) in a hope to find out why MySQL hangs. In the process the question appeared on how to find the thread id for each thread to match it against previous collected outputs of SHOW PROCESSLIST. and SHOW ENGINE INNODB STATUS.

I assumed I know the answer, as I had to find this out recently enough for this blog post (and before that for the real customer case). The idea is simple. Find a frame where function has a parameter of THD * type (usually named thd), like this:
#10 0x0000000000cb47fe in do_command (thd=0x7f32512b7000)
    at …

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Fun with Bugs #46 - On Some Bugs I've Reported During the Year of 2016

It's time to summarize the year of 2016. As a kind of a weird summary, in this post I'd like to share a list of MySQL bug reports I've created in 2016 that are still remaining "Verified" today:

  • Bug #79831 - "Unexpected error message on crash-safe slave with max_relay_log_size set". According to Umesh this is not repeatable with 5.7. The fact that I've reported the bug on January 4 probably means I was working at that time. I should not repeat this mistake again next year.
  • Bug #80067 - "Index on BIT column is NOT used when column name only is used in WHERE clause". People say the same problem happens with INT and, what may be even less expected, BOOLEAN columns.
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Testing (again) LOAD DATA on MySQL 5.6, 5.7, 8.0 (non-GA) and MariaDB 10.0, 10.1 and 10.2 (non-GA)

I’ve been lately compiling and generating .deb packages for several MySQL and MariaDB recent versions, and I wanted to try them more in depth -specially MySQL 8.0 and MariaDB 10.2, both of which are still in development.

Several people have already given their first impressions (or will do soon), and testing early is the best way to catch bugs and regressions, and get them fixed before the official release. In fact, as I will comment later, I ran into breaking bugs on both MySQL 8.0 and MariaDB 10.2, which I …

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MySQL Support Engineer's Chronicles, Issue #1

I have a habit to keep a log of everything I work on (or even just read about while working) every day. It's just a plain text file, with date labels, where most lines are URLs of issues and bugs I contributed to somehow, and my comments on what I did and why. But there are also code fragments, texts, copy-pasted outputs and links to interesting sites, articles and documentation.

Some of lines from this log I post on Facebook separately as I add them, these are mostly related to MySQL bugs and other things that annoy me. I know that some of my Facebook friends actually do not like this kind of posts at all... When I used LiveJornal actively, I've posted digests of my log from time to time (you can check what was there if you read Russian). But that digests …

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PerconaLive Amsterdam 2016 - Talks and shows

With Oracle Open World behind us, we are now getting ready for the next big event, i.e. the European edition of PerconaLive. I am going to be a presenter three times:

  • MySQL operations in Docker is a three-hour tutorial, and it will be an expansion of the talk by the same title presented at OOW. Attendees who want to play along can do it, by coming prepared with Docker 1.11 or later and the following images already pulled (images with [+] are mandatory, while [-] are optional):

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MySQL at Oracle Open World 2016

MySQL is a growing presence at Oracle Open World. While most of the headlines belong to the main products, where Oracle services are aiming at world domination, MySQL shared the spotlight, as it was announced to be part of Oracle database cloud. It seems a logical move for Oracle: after all the effort to make MySQL 5.7 the biggest release ever, it stands to reason that it is offered as a competitive feature in its own database as a service.

With this offer, Oracle is applying enterprise pricing and methodologies to a target of emerging companies. MySQL in the Oracle cloud differs from the competition by a few key points:

  • It's only MySQL 5.7. While this is the most advanced MySQL server …
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