CODEWITHSUNDEEP
pythondatabasedjangodatabase-connectiondjango-orm
pajton
pajton

Reputation: 16226

Database connection management when using only Django ORM

I am using Django ORM layer outside of Django. The project is a web application using a cusotm in-house built framework.

Now, I had no problems to set up Django ORM to run standalone, but I am a little bit worried about connection management. I have read Using only DB part of Django here at SO and it is true that Django does some special connection handling at the beginning and the end of each request. From django/db/__init__.py:

# Register an event that closes the database connection
# when a Django request is finished.
def close_connection(**kwargs):
    for conn in connections.all():
        conn.close()
signals.request_finished.connect(close_connection)

# Register an event that resets connection.queries
# when a Django request is started.
def reset_queries(**kwargs):
    for conn in connections.all():
        conn.queries = []
signals.request_started.connect(reset_queries)

# Register an event that rolls back the connections
# when a Django request has an exception.
def _rollback_on_exception(**kwargs):
    from django.db import transaction
    for conn in connections:
        try:
            transaction.rollback_unless_managed(using=conn)
        except DatabaseError:
            pass
signals.got_request_exception.connect(_rollback_on_exception)

What problems can I run into if I skip this connection management? (I have no way to plug in those signals into my framework easily)

Upvotes: 1

Views: 2497

Answers (1)

AdamKG
AdamKG

Reputation: 14081

It depends on your use case. Each of these functions do something specific, which may or may not affect you.

If this is a long-running process and you have DEBUG on, you'll need to reset the queries or it'll keep all the queries you've run in memory.

If you spawn lots of threads, connect to the DB once early on in each thread, and then leave the threads running, you'll also want to close the connections when you're done using the DB, or you could hit your DB's connection limit.

You almost certainly don't need _rollback_on_exception - I'm assuming you have your intended transaction behavior set up within the relevant code itself.

Upvotes: 1

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