How can I easily convert a Django app from mySQL to PostgreSQL? - mysql

Question

Has anyone done this? Is it an easy process? We're thinking of switching over for transactions and because mysql seems to be "crapping out" lately.

Answer 1

Converting MySQL database to Postgres database with Django
First backup your data of the old Mysql database in json fixtures:
$ python manage.py dumpdata contenttypes --indent=4 --natural-foreign > contenttype.json
$ python manage.py dumpdata --exclude contenttypes --indent=4 --natural-foreign > everything_else.json
Then switch your settings.DATABASES to postgres settings.
Create the tables in Postgresql:
$ python manage.py migrate
Now delete all the content that is automatically made in the migrate (django contenttypes, usergroups etc):
$ python manage.py sqlflush | ./manage.py dbshell
And now you can safely import everything, and keep your pk's the same!
$ python manage.py loaddata contenttype.json
$ python manage.py loaddata everything_else.json
Tested with Django==1.8

Answer 2

I just used this tool to migrate an internal app and it worked wonderfully. https://github.com/maxlapshin/mysql2postgres

Answer 3

You can do that using Django serializers to output the data from MySQL's format into JSON and then back into Postgres. There are some good artices on internet about that:
Migrating Django from MySQL to PostgreSQL the Easy Way
Move a Django site to PostgreSQL: check

Answer 4

I've never done it personally, but it seems like a combination of the dumpdata and loaddata options of manage.py would be able to solve your problem quite easily. That is, unless you have a lot of database-specific things living outside the ORM such as stored procedures.

Answer 5

I've not done it either.
I'd first follow this migration guide, there is a MySql section which should take care of all your data. Then django just switch the mysql to postgre in the settings. I think that should be ok.
I found another question on stackoverflow which should help with the converting mysql to postgre here.

Answer 6

python manage.py dump.data >> data.json
Create database and user in postrgesql
Set your just created database in postrgesql as default database in django settings or use param --database=your_postrgesql_database next steps
Run syncdb for create tables.
python syncdb [--database=your_postrgesql_database] --noinput
Create dump without data, drop all tables and load dump. Or truncate all tables (table django_content_type whith data which can be not equals your old data - it is way to many errors). At this step we need empty tables in postgresql-db.
When you have empty tables in postgresql-db just load your data:
python manage.py loaddata data.json
And be fun!

Answer 7

I wrote a Django management command that copies one database to another:
https://gist.github.com/mturilin/1ed9763ab4aa98516a7d
You need to add both database in the settings and use this command:
./manage.py copy_db from_database to_database app1 app2 app3 --delete --ignore-errors
What cool about this command is that it recursively copy dependent objects. For example, if the model have 2 foreign keys and two Many-to-Many relationships, it will copy the other objects first to ensure you won't get foreign key violation error.