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Displaying posts with tag: speculations (reset)
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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MySQL Support Engineer's Chronicles, Issue #4

This week I had to deal with some unusual problems. But let me start with Percona's xtrabackup, software that I consider a key component of many current production MySQL setups and use regularly. Recently new minor versions of XtraBackup were released, check the details on 2.4.5, for example. It made a step towards support of MariaDB 10.2, but it's still a long way to go, see this pull request #200.

My main problem with xtrabackup, though, is not with lack of support of MariaDB 10,2-specific features. Why should they care, after all... The problem is that old well known bugs and problems are not resolved, those that may affect all MySQL versions, forks and environments. Check  …

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MySQL Support Engineer's Chronicles, Issue #3

The original idea of this series was to publish one post per week, but it seems every other week I have some special topic that well deserves a dedicated post. Last week I had no time to complete my writing because of long (and, I hope, useful) Howto post on replacing corrupted partition using non-corrupted one from other server in replication setup. But I had links and notes collected in a draft that I am going to complete now.

First of all, during the previous week I had time to submit two more talks for the  …

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MySQL Support Engineer's Chronicles, Issue #2

It's time to continue my new series that I've started 2 weeks ago. I'd like to start with a reminder that it's time to send your talks for "MySQL and Friends Devroom" at FOSDEM 2017 - the only MySQL-related event next year that I plan to attend in any case. It seems we have one more week to submit, but I've already filled in all the details for the "main" talk, "Understanding MyRocks locks and deadlocks". I'd like to apply my usual source code reading and gdb breakpoints approach in case if by the end of January, 2017 official documentation still misses important details. Official MySQL …

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Fixing Broken MySQL Replication: Basic Usage of pt-table-checksum, pt-slave-restart and pt-table-sync

For second day in a row I am trying to concentrate on writing a second issue for my new series of blog posts, but I can not complete. It seems half of it is going to be devoted to three tools from Percona Toolkit that I had to remember and explain this week: pt-table-checksum, pt-table-sync and pt-slave-restart. So, I decided to write a separate post on this topic.

The context was simple: in the middle of (the weekend) night customer comes with broken replication issue, without a fresh backup from master or with few gigabytes …

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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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Fun with Bugs #45 - On Some Bugs Fixed in MySQL 5.7.15

Oracle released MySQL 5.7.15 recently, earlier than expected. The reason for this "unexpected" release is not clear to me, but it could happen because of a couple of security related internal bug reports that got fixed:

  • "It was possible to write log files ending with .ini or .cnf that later could be parsed as option files. The general query log and slow query log can no longer be written to a file ending with .ini or .cnf. (Bug #24388753)
  • Privilege escalation was possible by exploiting the way REPAIR TABLE used temporary files. (Bug #24388746)"

Let me concentrate on the most important fixes to bugs and problems reported by Community users. …

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Fun with Bugs #44 - Community Bugs Fixed in MySQL 5.7.14

MySQL 5.7.14 was officially released yesterday. So, it's time to check what bugs reported by MySQL Community in public were fixed in this release. Some of these bugs are presented below.

As usual, let me start with InnoDB. The following bugs were fixed there:

  • Bug #80296 - "FTS query exceeds result cache limit". It was reported (for 5.6, but I do not see new 5.6 release notes yet) by Monty Solomon and verified by Umesh.
  • Bug #80304 - "generated columns don't work with foreign key actions". It was reported by Guilhem Bichot based on test case by Peter Gulutzan presented …
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Fun with Bugs #43 - Bugs Fixed in MySQL 5.7.13

For some reason I do not see numerous public announcements about recent MySQL 5.7.13 release, even though it happened a couple of days ago formally. Maybe that's because we do not have any really "big" new features in this release (new ->> operator for introduced though for those who, unlike me, care about JSON). Still there are many fixes for bugs previously reported by Community (or Oracle engineers, but still in public bugs database), and I'd like to discuss some of them.

Let me start with the bug that was NOT fixed though, Bug #81093, "mysqld_multi not included in mysql-community-server package", reported by Georgi Iovchev and …

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Fun with Bugs #42 - Bugs Fixed in MySQL 5.7.12

MySQL 5.7.12 was released more than 2 weeks ago. New features introduced there in a form of "rapid plugins" are widely discussed, but I am more interested in bugs reported by MySQL Community users that are fixed there. Unfortunately I do not see MySQL Community Release Notes by Morgan (like this) for quite a some time, so I have to continue describing key bug fixes and name people who reported and verified bugs in my "Fun with Bugs" series.

As usual, let's start with InnoDB bugs fixed:

  • Bug #80070 - "allocated_size and file_size differ if create general tablespace outside datadir". It was reported by my former colleague from Percona …
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