For some reason the Committee of FOSDEM 2019 MySQL, MariaDB & Friends Devroom of all my talks submitted picked up the one on how to create a useful MySQL bug report, so I have no options but continue to write about MySQL bugs, as long and MySQL Community wants and even prefers to listen and read about them... That's what I do, with pleasure.

Today I'll continue my series of posts about community bug reports I am subscribed to with the review of bugs reported since October 1, 2018, starting from the oldest and skipping those MySQL 8 regression ones I've already commented on:

• …

More than 2 months passed since my previous review of active MySQL bug reports I am subscribed to, so it's time to describe what I was interested in this summer.

Let's start with few bug reports that really surprised me:

• Bug #91893 - "LOAD DATA INFILE throws error with NOT NULL column defined via SET". The bug was reported yesterday and seem to be about a regression in MySQL 8.0.12 vs older versions. At least I have no problem to use such a way to generate columns for LOAD DATA with MariaDB 10.3.7.
• Bug #91847 - "Assertion `thread_ids.empty()' failed.". As usual, Roel Van de Paar …

Several MySQL releases happened yesterday, but of them all I am mostly interested in MySQL 5.7.23, as MySQL 5.7 (either directly or indirectly, via forks and upstream fixes they merge) is probably the most widely used MySQL GA release at the moment.

In this post (in a typical manner for this "Fun with Bugs" series)  I'd like to describe several bugs reported by MySQL Community users and fixed in MySQL 5.7.23. As usual, I'll try to concentrate mostly on InnoDB, replication, partitioning and optimizer-related bugs (if any).

In one of my previous posts I stated that in Oracle's MySQL server some old enough features remain half-backed, not well tested, not properly integrated with each other, and not documented properly. It's time to prove this statement.

I should highlight from the very beginning that most of the features I am going to list are not that much improved by other vendors. But they at least have an option of providing other, fully supported storage engines that may overcome the problems in these features, while Oracle's trend to get rid of most engines but InnoDB makes MySQL users more seriously affected by any problems related to InnoDB.

Back in April I was preparing for vacations that my wife and I planned to spend in UK. Among other things planned I wanted to visit a customer's office in London and discuss few MySQL and MariaDB related topics, let's call them "stories". I tried to prepare myself for the discussion and collected a list of known active bugs (what else could I do as MySQL entomologist) for each of them. Surely live discussion was not suitable to share lists of bugs (and for some "stories" they were long), so I promised to share them later, in my blog. Time to do what I promised had finally come!

One of the stories we briefly discussed was "partitioning story". Right now I can immediately identify at least 47 active MySQL bugs in the related …

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 …

Oracle had formally released MySQL 5.7.21 yesterday. I do not bother any more to study MySQL release notes carefully and completely, but during a quick review today I've noted several interesting items I'd like you to pay attention to.

I am historically interested in InnoDB implementation details, so I could not miss Bug #87619 - "InnoDB partition table will lock into the near record as a condition in the use ". This was a regression bug in 5.7+, probably caused by new implementation of partitioning in InnoDB.

Another interesting bug is Bug #86927 - "Renaming a partitioned table does not update mysql.innodb_table_stats.", by …

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    …

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 …

This week is special and full of anniversaries for me. This week 5 years ago I left Oracle behind and joined Percona... Same week 5 years ago I had written something about MySQL in this blog for the first time in my life. 5 years ago I've created my Facebook account that I actively (ab)use for discussing work-related issues. So, to summarize, it's a five years anniversary of my coming out as a MySQL Entomologist, somebody who writes and speaks about MySQL and bugs in MySQL in public! These 5 years were mostly awesome.

I decided to celebrate with yet another post in this relatively new series and summarize in short what interesting things I studied, …