Michael Radziej wrote:
> DavidA:
> >
> > DavidA wrote:
> >> I have some models that look like this
> >>
> >> class Analyst(models.Model):
> >> name = models.CharField(maxlength=20, unique=True)
> >>
> >> class Strategy(models.Model):
> >> name = models.CharField(maxlength=20)
> >> description = models.CharField(maxlength=80)
> >>
> >> class Inst(models.Model):
> >> strategy = models.ForeignKey('Strategy', blank=True, null=True)
> >> analyst1 = models.ForeignKey('Analyst', related_name='analyst1',
> >> blank=True, null=True)
> >> analyst2 = models.ForeignKey('Analyst', related_name='analyst2',
> >> blank=True, null=True)
> >> analyst3 = models.ForeignKey('Analyst', related_name='analyst3',
> >> blank=True, null=True)
> >>
> >> class Position(models.Model):
> >> date = models.DateField(db_index=True)
> >> inst = models.ForeignKey(Inst)
> >> quantity = fields.NumberField()
> > [...]
> > Neither table (Analyst or Strategy) is being cached - both expressions
> > result
> > in 20 separate select queries but its going back to the DB for the same
> > ID many times. That still seems like a problem to me.
>
> select_related does not read in the tables that are related with
> null=True, like in your case. I don't know the reason for it,
> though. Would like to know, too ;-)
>
> Michael
Thanks, that explains it. I would guess that the reason they aren't
joined in is because it uses inner joins and you'd drop rows. I wonder
if you could just use an outer join for null FKs or if its more
complicated than that.
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