Downgrading Binary and Package-based Installations on Unix/Linux

Let us understand how to downgrade binary and package-based installation on Unix or Linux. Downgrading binary and package based installations on Unix or Linux can be done in a variety of ways. They have discussed below.

In-Place Downgrade

• In-place downgrade involves shutting down the new MySQL version.

• Once this is done, the new MySQL binaries or packages are replaced with the old binaries or packages.

• Once this is done, the old MySQL version is restarted on the existing data directory.

• MySQL has to be configured to perform a slow shutdown by setting innodb_fast_shutdown to 0.

The below command would do the same −

mysql -u root -p --execute="SET GLOBAL innodb_fast_shutdown=0"

Shut down the newer MySQL server. This can be done using the below commands −

mysqladmin -u root -p shutdown

After the slow shutdown, the InnoDB redo log files are removed (the ib_logfile* files) from the data directory. This is done to avoid downgrade issues that are associated with the redo log file format which would have occurred between releases.

Logical Downgrade

• Logical downgrade involves usage of mysqldump to dump all tables from the new MySQL version.

• Once this is done, the dump file is loaded into the old MySQL version.

• Logical downgrades are supported for downgrades between releases within the same release series as well as for downgrades to the previous release level.

• Only downgrades between General Availability (GA) releases are supported.

• Dump all the databases. This is done using the below command −

mysqldump −u root −p
   −−add−drop−table −−routines −−events
   −−all−databases −−force > data−for−downgrade.sql

The newer MySQL server is shut down using the below command −

mysqladmin −u root −p shutdown