django_nplusone

Discover possible N+1 queries in Django ORM at runtime

The objective of this library is to help you discover any N+1s in your code at development time. Enable logging of warnings by following instructions shown in Usage section. Run your Django app as usual and you will see warning logs of any possible N+1s if found.

Installation

Install the package from PyPI using pip as following

pip install django_nplusone

Usage

Once package is installed, you can register the package in your settings.py as:

import nplusone

if DEBUG:
    nplusone.show_nplusones()

This should start logging possible N+1s warnings using your logger configuration. The library uses standard python logging module and uses logger by the name of nplusone.

Ignore specific warnings

You can ignore warning for a specific statement by ending the statement with # NO-NPLUSONE.

Test

You can test the N+1 warning logging by putting some code as shown below somewhere in your application code that you know will get executed. Say you have a model User with a foreign key field org to Organization model.

user = User.objects.all()[0]
print(user.org)

You should see a log message with a message that looks like this:

... Possible N+1 for model: User, field: org, relationship: ForwardManyToOne, file: <?>, function: <?>, line: <?>, statement: <?>

where <?> will have correct values for the fields derived from call stack pointing you to the statement that has possible N+1