J-F Gagné's MySQL Blog

Tuesday, November 30, 2021

Follow-up on an Unprivileged User can Crash your MySQL Server

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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...
Friday, November 12, 2021

Duplicate Entry in ALTER TABLE (and in OPTIMIZE TABLE)

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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...
7 comments:
Saturday, December 5, 2020

Fixing low durability GTID replica with Voodoo

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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.  ...
Sunday, October 18, 2020

An Unprivileged User can crash your MySQL Server

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Yes, your read the title correctly: an unprivileged user can crash your MySQL Server.  This applies for the default configuration of MySQL 8...
Sunday, June 7, 2020

Update on Planet for the MySQL Community (June 7, 2020)

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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...
1 comment:
Thursday, May 14, 2020

Planet [for the] MySQL Community: Pluto Beta

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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...
4 comments:
Tuesday, May 12, 2020

Planet MySQL Community: Requirements RFC

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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...
2 comments:
Friday, April 24, 2020

Planning for the AFTER Planet MySQL (bis)

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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...

Planning for the AFTER Planet MySQL

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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 ...

State of Planet MySQL: unhealthy !

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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 ...
6 comments:
Monday, March 30, 2020

JFG MySQL Advice during COVID-19

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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...
Monday, January 27, 2020

A Legacy Behavior of MySQL Corrupting Restored Backups (replicate-same-server-id = OFF)

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In my previous post ( Puzzled by MySQL Replication ), I describe a weird, but completely documented, behavior of replication that had me scr...
Thursday, January 9, 2020

Puzzled by MySQL Replication (War Story)

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Recently, I was puzzled by MySQL replication !  Some weird, but completely documented, behavior of replication had me scratching my head for...
5 comments:
Monday, October 7, 2019

The dark side of super_read_only

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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...
2 comments:
Tuesday, July 16, 2019

MySQL Master Replication Crash Safety Part #5a: making things faster without reducing durability - using better hardware

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

MySQL Master Replication Crash Safety Part #5: faster without reducing durability (under the hood)

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This post is a sister post to MySQL Master Replication Crash Safety Part #5: making things faster without reducing durability.  There is no ...
2 comments:
Tuesday, July 9, 2019

MySQL Master Replication Crash Safety Part #4: benchmarks of high and low durability

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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...
5 comments:

MySQL Master Replication Crash Safety part #4: benchmarks (under the hood)

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This post is a sister post to MySQL Master Replication Crash Safety Part #4: benchmarks of high and low durability .  There are no introduct...
Tuesday, June 25, 2019

Getting past 2400 threads with sysbench and dbdeployer for benchmarking MySQL 5.7.26

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I am currently running tests with sysbench  and  dbdeployer on a Google Cloud Platform Debian 9 instance.  I ran into an interesting limit...
Wednesday, May 8, 2019

Not enforcing SSL on CloudSQL, really !

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When creating a MySQL CloudSQL instance, SSL connections are not enforced by default and you get below in the Connections tab of the Goog...
4 comments:
Wednesday, May 1, 2019

Care with using the max_connections beta database flag on CloudSQL...

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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...
2 comments:
Tuesday, February 26, 2019

MySQL Master High Availability and Failover: more thoughts

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Some months ago, Shlomi Noach published a series about Service Discovery .  In his posts, Shlomi describes many ways for an application to f...
10 comments:
Tuesday, February 12, 2019

MySQL Master Replication Crash Safety Part #3: GTID

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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...
Tuesday, January 8, 2019

Care when changing MASTER_DELAY with CHANGE MASTER TO (delayed replication)

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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...
4 comments:
Thursday, November 15, 2018

MySQL Master Replication Crash Safety Part #2: lagging slaves

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This is Part #2 of the MySQL Master Replication Crash Safety series.  In the previous post, we explored the consequence of reducing durabili...
5 comments:
Tuesday, November 13, 2018

How to install Percona Server 5.7 on Debian/Ubuntu without a root password prompt

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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...
Tuesday, October 30, 2018

On the consequences of sync_binlog != 1 (part #1)

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A well-known performance booster in MySQL is to set sync_binlog to 0.  However, this configuration alone comes with serious consequences on...
6 comments:
Tuesday, October 23, 2018

Arg: relay_log_space_limit is (still) not dynamic !

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This will be a short rant: why is relay_log_space_limit still not dynamic ?
Tuesday, September 11, 2018

Unforeseen use case of my GTID work: replicating from AWS Aurora to Google CloudSQL

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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...
Monday, August 27, 2018

Another Post on the Percona Community Blog, Bug Activities on Replication Crash Safety, and Percona Live Europe

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I published another article on the Percona Community Blog .  This time, it is about Semi-Synchronous Replication.  You can read the post her...
Thursday, June 28, 2018

JFG Posted on the Percona Community Blog - A Nice Feature in MariaDB 10.3: no InnoDB Buffer Pool in Core Dumps

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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...
1 comment:
Thursday, April 19, 2018

Some bugs and spring pilgrimage to Percona Live Santa Clara 2018

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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...
Saturday, January 27, 2018

Next week in Brussels: Parallel Replication at the MySQL Pre-FOSDEM Day

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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...
Thursday, January 11, 2018

More Write Set in MySQL: Group Replication Certification

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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...
2 comments:
Monday, January 8, 2018

Write Set in MySQL 5.7: Group Replication

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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...
3 comments:
Wednesday, January 3, 2018

An update on Write Set (parallel replication) bug fix in MySQL 8.0

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In my MySQL Parallel Replication session at Percona Live Santa Clara 2017 , I talked about a bug in Write Set tracking for parallel replica...
2 comments:
Tuesday, November 28, 2017

Here is the CREATE TABLE of death

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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...
4 comments:
Thursday, October 19, 2017

A crashing bug in MySQL: the CREATE TABLE of death (more fun with InnoDB Persistent Statistics)

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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 ...
5 comments:
Wednesday, August 16, 2017

The danger of no Primary Key when replicating in RBR (and a partial protection with MariaDB 10.1)

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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 ...
1 comment:
Monday, August 14, 2017

More Details about InnoDB Compression Levels (innodb_compression_level)

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In one of my previous posts, I shared InnoDB table compression statistics for a read-only dataset using the default value of  innodb_compre...
Thursday, August 10, 2017

Why we still need MyISAM (for read-only tables)

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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...
12 comments:
Monday, August 7, 2017

An Adventure in InnoDB Table Compression (for read-only tables)

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In my last post about big MySQL deployments , I am quickly mentioning that InnoDB compression is allowing dividing disk usage by about 4.3...
4 comments:
Monday, July 24, 2017

How far can you go with MySQL or MariaDB ?

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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...
10 comments:
Wednesday, July 19, 2017

InnoDB Basics - Compaction: when and when not

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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 ...
5 comments:
Wednesday, July 5, 2017

Fun with InnoDB Persistent Statistics

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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...
Monday, May 22, 2017

Better Replication when running both InnoDB and MyRocks (or other Storage-Engines)

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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...
Friday, April 21, 2017

My two parallel replication talks at Percona Live Santa Clara 2017

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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...
3 comments:
Tuesday, April 18, 2017

My talks at Percona Live Santa Clara 2017

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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...
Sunday, April 16, 2017

Booking.com talks at Percona Live Santa Clara 2017

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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...
Tuesday, April 11, 2017

Many thanks Oracle for implementing RESET MASTER TO

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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...
1 comment:
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Jean-François Gagné
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