Improving run time of simple query

Question

Gurus:

I have a very simple data model relating two different kinds of User s via an Interaction :

# myapp/models.py
class C1(models.Model):
 user = models.ForeignKey(User)

class C2(models.Model):
 user = models.ForeignKey(User)

class Interaction(models.Model):
 c1 = models.ForeignKey(C1)
 c2 = models.ForeignKey(C2)
 date = models.DateField()

So, an Interaction has a User of class C1 , a User of class C2 , and a date (in addition to the primary key, automatically an integer); a given pair of users can have many Interaction s.

I populated the database with 2000 random User s (1000 each class), and when I query the Interaction the run time is too slow (about three seconds - unacceptable in production environment).

Is there something I can do to improve the run time of this search? Should I define the Interaction differently?

Thanks.

Answer 1

If you'd like to store additional information related to your users, Django provides a method to specify a site-specific related model -- termed a "user profile" -- for this purpose.

To make use of this feature, define a model with fields for the additional information you'd like to store, or additional methods you'd like to have available, and also add a OneToOneField from your model to the User model. This will ensure only one instance of your model can be created for each User. For example:

# settings.py
AUTH_PROFILE_MODULE = 'myapp.UserProfile'

# myapp/models.py
class UserProfile(models.Model):
    CLASS_CHOICES = (
        (0, 'Yellow User'),
        (1, 'Green User'),
    )
    user_class = models.IntegerField(choices=CLASS_CHOICES)
    user = models.OneToOneField(User)

class Interaction(models.Model):
    u1 = models.ForeignKey(User, related_name='u1s')
    u2 = models.ForeignKey(User, related_name='u2s')
    date = models.DateField()

Creating a new model and associated table for each User class seems not like good design.

Answer 2

You have used foreign keys to associate C1, C2 with Users , and called this a one-to-many relationship . However, the relationship between Interaction C1, C2 is not one-to-many because one Interaction can be associated with many Users , and one User can also have many Interactions associated with it. This is called a many-to-many relationship , and is represented in Django models using models.ManyToManyField .

So try changing your models.py file to -

class Interaction(models.Model):
    ic1 = models.ManyToManyField(C1)
    ic2 = models.ManyToManyField(C2)
    date= models.DateField()

See if this helps...