There is always a risk and also a problem when altering a production mySQL table. Percona has released a toolkit that contains a command called pt-online-schema-change. It will change table schema live on production without downtime.

Installation steps on Debian:

1- wget https://repo.percona.com/apt/percona-release_0.1-4.$(lsb_release -sc)_all.deb

2- sudo dpkg -i percona-release_0.1-4.$(lsb_release -sc)_all.deb

3- sudo apt-get update

4- sudo apt-get install percona-toolkit

Now you have percona toolkit on your Debian server. Use the command pt-online-schema-change for your table alteration.

#mysql #percona #schema #alter_table #online_schema_change #percona_toolkit #pt_online_schema_change

In order to dry run before the real execution use --dry-run:

pt-online-schema-change --dry-run  h=127.0.0.1,D=YOUR_DB,t=YOUR_TABLE --alter "ADD COLUMN (foobar varchar(30) DEFAULT NULL);"

Now after dry run you can execute the alter command:

pt-online-schema-change --execute  h=127.0.0.1,D=YOUR_DB,t=YOUR_TABLE --alter "ADD COLUMN (foobar varchar(30) DEFAULT NULL);"

#mysql #percona #schema #alter_table #online_schema_change #percona_toolkit #pt_online_schema_change