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Displaying posts with tag: bugs (reset)
Fun with Bugs #61 - On MySQL Bug Reports I am Subscribed to, Part III

Since my previous post on this topic I've subscribed to 19 more MySQL bugs, so it's time for yet another review of these reports. I am trying to pick up important, funny or hard to process reports every day, and here is the list of the most interesting ones starting from the latest:

  • Bug #89607 - "MySQL crash in debug, PFS thread not handling singals." We have a patch contributed by Robert Golebiowski.
  • Bug #89583 - "no rpm build instructions from source git tree". As Simon Mudd put it:
    "... The sources are supposed to be in the git tree …
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On InnoDB's Online DDL

I am completing my preparations for the upcoming FOSDEM talk, and one of last things I wanted to do in frames of them is a quick review of known bugs and problems in current (as in MySQL 5.7 GA) implementation of so called "online" DDL for InnoDB tables.

In my previous post I already shared my view on another important InnoDB feature, persistent statistics. Unlike that, I do not really hate online DDL. I just try to avoid it if possible and use tools like pt-online-schema-change or gh-ost instead. Not because it is not documented properly (the …

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On InnoDB's Persistent Optimizer Statistics

As I put it in recent Facebook post, one of MySQL features that I truly hate is InnoDB's persistent statistics. I think I should clarify this statement. It's great to have a way to save statistics in between server restarts, to have better control on the way it is estimated (even on a per table basis), set it explicitly, check it with simple SELECT. These all are great additions since MySQL 5.6.2+ that I truly appreciate (even if I may not be happy with some implementation details). They helped to make plans for queries against InnoDB more predictable and allow (with some efforts applied) MySQL query optimizer to really work as "optimizer" instead of "randomizer" or "pessimizer" (as some people called it) for InnoDB tables.

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Updates to 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 bug tracking system.

Assuming everything goes according to schedule, on December 28, 2017, we will copy all bug reports in Launchpad into the appropriate JIRA projects (with the appropriate issue state). The new JIRA issue will link to the original Launchpad issue, and the new JIRA issue link is added to the original Launchpad issue. Once this is done, we will then turn off editing on the Launchpad projects.

Q&A Which Launchpad projects are affected?

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Fun with Bugs #58 - Bug of the Day From @mysqlbugs

In 2013 I had a habit of writing about MySQL bugs on Facebook almost every day. Typical post looked like this one, link to the bug and few words of wondering with a bit of sarcasm.
By the way, check last comments in Bug #68892 mentioned there - the problem of LOST_EVENTS in master's binary log and a way to workaround it still valid as of MySQL 5.7.17.At that time I often got private messages from colleagues that Facebook is a wrong media for this kind of posts, these posts make MySQL look "buggy" etc, and eventually I was shut up

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Using strace for MySQL Troubleshooting

I'd say that strace utility is even more useful for MySQL DBAs than lsof. Basically, it is a useful general purpose diagnostic and debugging tool for tracing system calls some process makes and signals it receives. The name of each system call, its arguments and its return value are printed to stderr or to the file specified with the -o option.

In context of MySQL strace is usually used to find what files mysqld process accesses, and to check the details about any I/O errors. For example, if I'd really want to try to verify Bug #88479 - "Unable to start mysqld using a single config file (and avoiding reading defaults)" by Simon …

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How lsof Utility May Help MySQL DBAs

While working in Support, I noticed that probably at least once a week I have to use or mention lsof utility in some context. This week, for example, we had a customer trying to find out if his mysqld process running is linked with tcmalloc library. He started it different ways, using LD_PRELOAD directly and --malloc-lib option of mysqld_safe script etc, but wanted to verify that his attempts really worked as expected. My immediate comment in the internal chat was: "Just let them run lsof -p `pidof mysqld` | grep mall and check!" My MariaDB 10.2 instance uses jemalloc and this can be checked exactly the same way:
openxs@ao756:~/dbs/maria10.2$ ps aux | grep mysqld...
openxs    4619  0.0  0.0   4452   804 pts/2    S    …

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Fun with Bugs #57 - On MySQL Bug Reports I am Subscribed to, Part I

I've decided to stop reviewing MySQL Release Notes in this series, but it does not mean that I am not interested in MySQL bugs any more. At the moment I am subscribed to 91 active MySQL bugs reported by other MySQL users, and in this blog post I am going to present 15 of them, the most recently reported ones. I'd really want to see them fixed or at least properly processed as soon as possible.

In some cases I am going to add my speculations on how the bug had better be handled, or maybe highlight some important details about it. It is not my job any more to process/"verify" any community bug reports for any kind of MySQL, but I did that for many years and I've spent more than 5 years "on the other side", being a member of Community, so in some cases I let myself to share some strong opinion on what may be done …

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Fun with Bugs #56 - On Some Public Bugs Fixed in MySQL 5.7.20

While MySQL 8.0.x hardly has much impact on my regular work, recent MySQL 5.7.20 release is something to check carefully. MySQL 5.7 is widely used in production, as a base for Percona Server 5.7, some features may be merged into MariaDB 10.x etc. So, here is my review of some community reported bugs that were fixed in recently released MySQL 5.7.20, based on the release notes.

Usually I start with InnoDB bug fixes, but in 5.7.20 several related fixes were made only to bugs reported internally. So, this time I have to start with partitioning:

  • Bug #86255 - First one to write about, and the bug report is …
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Revisiting roles in MySQL 8.0

In my previous article about roles I said that one of the problems with role usage is that roles need to be activated before they kick in. Let's recap briefly what the problem is:

## new session, as user `root`

mysql [localhost] {root} ((none)) > create role viewer;
Query OK, 0 rows affected (0.01 sec)

mysql [localhost] {root} ((none)) > grant select on *.* to viewer;
Query OK, 0 rows affected (0.01 sec)

mysql [localhost] {root} ((none)) > create user see_it_all identified by 'msandbox';
Query OK, 0 rows affected (0.01 sec)

mysql [localhost] {root} ((none)) > grant viewer to see_it_all;
Query OK, 0 rows affected (0.01 sec)

## NEW session, as user `see_it_all`

mysql [localhost] {see_it_all} ((none)) > use test
ERROR 1044 (42000): Access denied for user …
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