J-F Gagné's MySQL Blog

A year ago, I blogged about An Unprivileged User can Crash your MySQL Server .  At the time, I presented how to protect yourself against thi...

A few weeks ago and in MySQL 5.7, I had an ALTER TABLE that failed with a duplicate entry error.  This is old news as it is happening since...

At my FOSDEM talk earlier this year, I gave a trick for fixing a crashed GTID replica.  I never blogged about this, so now is a good time.  ...

Yes, your read the title correctly: an unprivileged user can crash your MySQL Server.  This applies for the default configuration of MySQL 8...

Three weeks ago, I released the Pluto Beta of Planet for the MySQL Community .  Since then, a few things changed and I think it is worth doi...

As indicated in a previous post, I am working on Planet [for the] MySQL Community for which I did a RFC on the Requirements .  I am happy t...

As indicated in a previous post, I am working on a Planet MySQL Community (this name is not final, see below).  In this post, I want to pre...

Oups, my previous post had a forbidden word and did not show-up on Planet MySQL, so retry... As written in a previous post,  the state of...

As written in my previous post, the state of Planet MySQL is unhealthy  !  I am still aggregated there for now as, before leaving what was ...

Also, the state of bugs.mysql.com: unhealthy (last paragraph below, but this would be too long a title). I have been complaining for some ...

Update 2020-05-05 : I stopped providing consulting hours.  They were not very popular, but it was worth trying. We are all impacted by COV...

In my previous post ( Puzzled by MySQL Replication ), I describe a weird, but completely documented, behavior of replication that had me scr...

Recently, I was puzzled by MySQL replication !  Some weird, but completely documented, behavior of replication had me scratching my head for...

There is an interesting feature in MySQL 5.7+: the global variable super_read_only .  MySQL 5.6 and before only had the read_only global va...

This is a follow-up post in the MySQL Master Replication Crash Safety series.  In the previous posts, we explored the consequences of reduci...

This post is a sister post to MySQL Master Replication Crash Safety Part #5: making things faster without reducing durability.  There is no ...

This is a follow-up post in the MySQL Master Replication Crash Safety series.  In the three previous posts, we explored the consequence of r...

This post is a sister post to MySQL Master Replication Crash Safety Part #4: benchmarks of high and low durability .  There are no introduct...

I am currently running tests with sysbench  and  dbdeployer on a Google Cloud Platform Debian 9 instance.  I ran into an interesting limit...

When creating a MySQL CloudSQL instance, SSL connections are not enforced by default and you get below in the Connections tab of the Goog...

War story of the day: do not use — or be very careful when using — the max_connections beta database flag on CloudSQL ... because it has man...

Some months ago, Shlomi Noach published a series about Service Discovery .  In his posts, Shlomi describes many ways for an application to f...

This is a follow-up post in the MySQL Master Replication Crash Safety series.  In the two previous posts, we explored the consequence of red...

A few days ago, I stepped into a trap !  This made me lose time for fixing things (and even more for writing this post...).  In the hope tha...

This is Part #2 of the MySQL Master Replication Crash Safety series.  In the previous post, we explored the consequence of reducing durabili...

In the last few months, I had to install Percona Server 5.7  ( PS5.7 ) on Debian a few times.  I was regularly annoyed by  apt-get -y instal...

A well-known performance booster in MySQL is to set sync_binlog to 0.  However, this configuration alone comes with serious consequences on...

This will be a short rant: why is relay_log_space_limit still not dynamic ?

A colleague brought an article to my attention.  I did not see it on Planet MySQL where I get most of the MySQL news (or it did not catch m...

I published another article on the Percona Community Blog .  This time, it is about Semi-Synchronous Replication.  You can read the post her...

I just posted an article on the Percona Community Blog .  You can access it following this link: A Nice Feature in MariaDB 10.3: no InnoDB...

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 wr...

FOSDEM is next weekend and I am talking about Parallel Replication on Friday, February 2nd at the MySQL Pre-FOSDEM Day  ( there might be ti...

This is the third post in the series on Write Set in MySQL.  In the first post, we explore how Write Set allows to get better parallel repli...

In my previous post , I write that Write Set is not only in MySQL 8.0 but also in MySQL 5.7 though a little hidden.  In this post, I describ...

In my MySQL Parallel Replication session at Percona Live Santa Clara 2017 , I talked about a bug in Write Set tracking for parallel replica...

In a previous post , I talked about the existence of a CREATE TABLE that is crashing MySQL up to versions 5.5.58, 5.6.38 and 5.7.20, and Mar...

I ended one of my last posts - Fun with InnoDB Persistent Statistic s - with a cryptic sentence: there is more to say about this but I will ...

TL;DR : unless you know what you are doing, you should always have a primary key on your tables when replicating in RBR (and maybe even all ...

In one of my previous posts, I shared InnoDB table compression statistics for a read-only dataset using the default value of  innodb_compre...

TL;DR : we still need MyISAM and myisampack because it uses less space on disk (half of compressed InnoDB) ! In the previous post, I shar...

In my last post about big MySQL deployments , I am quickly mentioning that InnoDB compression is allowing dividing disk usage by about 4.3...

MySQL theoretical limits are known and they can be found in the manual, they include: MyISAM permits data and index files to grow up to 25...

This is old news for MySQL/MariaDB expert but people that are starting using InnoDB do not always know that disk space is not automatically ...

Something interesting happened to me in the last days, and it is worth sharing.  I was upgrading MariaDB (MySQL also impacted) to a new majo...

Kristian Nielsen is working on a new feature for MariaDB 10.3 and he published very interesting results.  This feature is MDEV-12179: Per-en...

Yes, another post about my talks at Percona Live Santa Clara : I obviously still have things to share.  This time, I will focus on my parall...

In a previous post, I listed all the Booking.com talks at Percona Live.  In this post, I will give more details about my talks. As a remi...

In a week, me and some Booking.com colleagues will be in Santa Clara for Percona Live . Booking.com is sponsoring the conference and we w...

MySQL 8.0.1 is out and it includes an implementation of my feature request ( Bug #77438 ).  This extension to RESET MASTER allows to simpli...