Install MySQL 5.6 in Ubuntu 16.04

Instead of using this hack you might want to use MariaDB 10.x which can work with both old and new apps.

An alternative could be to use the MySQL Docker image Show archive.org snapshot which is still updated for 5.6.

Ubuntu 16.04 only provides packages for MySQL 5.7 which has a range of backwards compatibility issues with code written against older MySQL versions.

Oracle maintains a list of official APT repositories for MySQL 5.6, but those repositories do not yet support Ubuntu 16.04. However, the 15.10 repos will work for 16.04.

I would not recommend to do this in production environment, but on a development machine, follow these steps:

• Dump your databases, if you want to keep them. Keeping the data directory itself did not work for me.

• Uninstall everything related to MySQL 5.7 with

  Copyapt remove mysql-client mysql-server libmysqlclient-dev mysql-common
  

  Check if you removed everything using

  Copydpkg -l | grep mysql
  

  Purge remainders (e.g. marked with rc) with dpkg -P <package> [<package> ...].

• Download the apt_config-debian package from Oracle Show archive.org snapshot and install it using

  Copydpkg -i mysql-apt-config_0.7.2-1_all.deb
  

  Choose "MySQL 5.6" and "Ubuntu Wily" (assuming Xenial is not yet provided)

• Run

  Copyapt-cache policy mysql-server  
  

  If this shows a 5.6 version, continue.

  If not, check your /etc/apt/sources.list.d/mysql.list. It should look roughly like this:

  Copy### THIS FILE IS AUTOMATICALLY CONFIGURED ###
  # You may comment out entries below, but any other modifications may be lost.
  # Use command 'dpkg-reconfigure mysql-apt-config' as root for modifications.
  deb http://repo.mysql.com/apt/ubuntu/ wily mysql-apt-config
  deb http://repo.mysql.com/apt/ubuntu/ wily mysql-5.6
  deb http://repo.mysql.com/apt//ubuntu/ wily mysql-tools
  deb-src http://repo.mysql.com/apt/ubuntu/ wily mysql-5.6
  

  You might have to replace "xenial" with "wily". Although you are using 16.04 (codename Xenial), Oracle currently seems to only provide 5.6 in the repos for 14.04 (codename Wiley). But those sources work for 16.04, too.

• Create a file /etc/apt/preferences.d/mysql with this content

  CopyPackage: *
  Pin: origin "repo.mysql.com"
  Pin-Priority: 999
  

• Run

  Copyapt update
  

• Run

  Copyapt install mysql-client mysql-server libmysqlclient-dev
  

  You should get 5.6 versions.

In case you have installed and MySQL ruby gems (like mysql2), you will have to remove and reinstall them, since they have been linked to the old libraries. Note that gem pristine will not help.