CODEWITHSUNDEEP
pythondjangopostgresql
1Up
1Up

Reputation: 1044

Django - Foreignkey and Many to Many References - How to Know Number of Queries?

How do I know if Django is running multiple queries when fetching a model that contains relations?

Here is an example:

class ModelOne(models.Model):

    '''...the stuff...'''

class ModelTwo(models.Model):
    something = models.ForeignKeyField(ModelOne)

    '''...all the things...'''

class ModelThree(models.Model):
    something_elses = model.ManyToManyField(ModelTwo)

class ModelFour(models.Model):
    now_this_is_just_silly = models.ManyToManyField(ModelThree)

So lets say I fetch ModelFour like so:

m = ModelFour.objects.all()[0]

It would be wonderful to think that, by default, all submodels all the way down to ModelOne are a part of it's datastructure. Is that the case?

If I start to navigate down the datastructure of ModelFour to access an attribute (the stuff) in ModelOne, am I performing multiple queries?

For the record, this is a postgres database setup, per django suggestion.

Upvotes: 0

Views: 64

Answers (2)

Bogdan Goie
Bogdan Goie

Reputation: 1307

To count nr of queries try using connection from django.db (make sure DEBUG=True in settings.py):

from django.db import connection

m = ModelFour.objects.all()[0]

print len(connection.queries)

...and if you just want to see the queries in a list, remove len

Upvotes: 1

Chris Montanaro
Chris Montanaro

Reputation: 18242

You can look at postgres' query count and check it again after your query has finished

Use this query to read total number of transactions executed in all databases:

SELECT sum(xact_commit+xact_rollback) FROM pg_stat_database;

If you want the same counter for just one database, use:

SELECT xact_commit+xact_rollback FROM pg_stat_database WHERE datname = 'mydb';

credit to: https://dba.stackexchange.com/questions/35940/how-many-queries-per-second-is-my-postgres-executing

You can list the current running queries with:

SELECT datname,procpid,current_query FROM pg_stat_activity

from: http://chrismiles.info/systemsadmin/databases/articles/viewing-current-postgresql-queries/

Upvotes: 1

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