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MySQL adjustment bureau


When maintainng any piece of software, we usually deal with two kind of actions:

  • bug fixing,
  • new features.

bugs and features

A bug happens when there is an error in the software, which does not behave according to the documentation or the specifications. In short, it's a breech of contract between the software maintainer and the users. The promise, i.e. the software API that was published at every major version, is broken, and the software must be reconciled with the expectations and fixed, so that it behaves again as the documentation says. When we fix a bug in this way, we increment the revision number of the software version (e.g. 1.0.0 to 1.0.1. See semantic …

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Fun with Bugs #67 - On Some Public Bugs Fixed in MySQL 8.0.11 GA

I stopped reviewing MySQL Release Notes for quite a some time, but major GA releases of MySQL do not happen often, so I decided to make an exception and write about some bugs from Community users fixed in MySQL 8.0.11 GA.

I'll start with good news about MySQL 8.0.11 GA! You can get sources at GitHub, and I had no problems to build on Fedora 27 on my good old QuadCore box, using the following cmake command line:
[openxs@fc23 mysql-server]$ cmake . -DCMAKE_BUILD_TYPE=RelWithDebInfo -DBUILD_CONFIG=mysql_release -DFEATURE_SET=community -DWITH_EMBEDDED_SERVER=OFF -DDOWNLOAD_BOOST=1 -DWITH_BOOST=/home/openxs/boost …

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Some bugs and spring pilgrimage to Percona Live Santa Clara 2018

I am now in an airport, waiting for one of the four flights that will bring me to Percona Live Santa Clara 2018.  This is a good time to write some details about my tutorial on parallel replication.  But before talking about Percona Live, I will share thoughts on MySQL/MariaDB bugs that caught my attention in the last weeks/months (Valeriy: you clearly have an influence on me).

MySQL/MariaDB

Fun with Bugs #66 - On MySQL Bug Reports I am Subscribed to, Part VI

I have some free time today, but I am still lazy enough to work on numerous planned and pending "ToDo" kind of posts, so why not to continue review of older MySQL bugs I am subscribed to. Today I am going to list 15 more bugs reported more than a year ago and still not fixed:

  • Bug #85805 - "Incorrect ER_BAD_NULL_ERROR after LOAD DATA LOCAL INFILE". This detailed bug report by Tsubasa Tanaka stays "Verified" for more than a year already. It's a great example of gdb use for MySQL troubleshooting. Setting a couple of breakpoints may really help to understand how MySQL works and why some …
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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 #64 - On MySQL Bug Reports I am Subscribed to, Part IV

I've subscribed to more than 15 new MySQL bug reports since the previous post in this series, so it's time for a new one. I am trying to follow important, funny or hard to process bug reports every day. Here is the list of the most interesting recent ones starting from the latest (with several still not processed properly):

  • Bug #90211 - "Various warnings and errors when compiling MySQL 8 with Clang".  Roel Van de Paar and Percona in general continue their QA efforts in a hope to make MySQL 8 better. Current opinion of Oracle …
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Fun With Bugs #62 - On Bugs Related to JSON Support in MySQL

Comparing to "online ALTER" or FULLTEXT indexes in InnoDB, I am not that much exposed to using JSON in MySQL. OK, there is EXPLAIN ... FORMAT=JSON statement that is quite useful, optimizer trace in MySQL is also in JSON format, but otherwise I rarely have to even read this kind of data since my lame attempt to pass one introductory MongoDB training couse back in 2015 (when I mostly enjoyed mongo shell). Even less I care about storing JSON in MySQL.

But it …

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On InnoDB's FULLTEXT Indexes

I had recently written about InnoDB features that I try to avoid by all means if not hate: "online" DDL and persistent optimizer statistics. Time to add one more to the list - FULLTEXT indexes.

This feature had a lot of problems when initially introduced in MySQL 5.6. There was a nice series of blog posts about the initial experience with it by my colleague from Percona (at that times) Ernie Souhrada: part I, …

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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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