[PYTHON] Test the application of migration files with Django + PostgreSQL (Evil Way)

Operation memorandum with Django + PostgreSQL for myself It's not the right way to do it, and it should be done in a straightforward manner. Described that there is also such a method.

The correctness of the procedure is not guaranteed.

Purpose

If you change the model in Django In the verification environment shared by everyone Respond after applying the migration file.

• Of course, as a straightforward method https://stackoverflow.com/questions/32123477/django-revert-last-migration It seems correct to do like this.

However, it is a corresponding procedure for those who are troublesome to write additional code.

Premise

--The command described in the procedure must be installed and executable. --The database name of the operation target is targetdb.

Procedure outline

--Prepare the backup destination database for the target database --Disconnect existing session --Back up the target database --Apply migration --Undo from backup

procedure

Prepare the backup destination database for the target database

Preparation of save destination database

$ createdb targetdb_evate;

Disconnect existing session

Disconnect the session connected to PostgreSQL. (Of course, after confirming that no operations have been performed)

Check existing sessions

$ psql
postgres=# select pid, datname from pg_stat_activity;

Specify the pid confirmed by the above command and throw the following SQL.

Disconnect session

postgres=# select pg_terminate_backend($pid) from pg_stat_activity;

• For $ pid, enter the pid confirmed in Checking the existing session.

Back up the target database

From the target database (targetdb) to the save destination database (targetdb_evade) Back up your data to.

Database backup

$ pg_dump -Ft targetdb | pg_restore -d targetdb_evade

If there are any sessions left, it will fail here.

Apply migration

Apply Django migrations in any way you like.

Apply migration

$ python manage.py migrate

After application, check the operation and execute various tests.

Undo from backup

Return to the state before migration from the save destination database ** Disconnect existing session ** Repeat steps to repeat Disconnect all sessions.

Delete the database (targetdb) to which migration has been applied, and Rename the saved database (targetdb_evade) and you're done.

Return from backup

$ psql
postgres=# drop database targetdb;
postgres=# alter database targetdb_evade rename to targetdb;