#27260: Performance Issue because of LEFT OUTER JOIN instead the better INNER
JOIN
-------------------------------------+-------------------------------------
Reporter: Sven R. Kunze | Owner: nobody
Type: | Status: new
Cleanup/optimization |
Component: Database layer | Version: 1.8
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Sven R. Kunze):
Replying to [comment:1 Tim Graham]:
> Please also provide your models.
{{{
class BigTable:
# a lot of unrelated fields
}}}
{{{
class TableA:
big_table = models.OneToOneField(BigTable, related_name='...',
primary_key=True)
item_id = models.CharField(max_length=1024)
}}}
{{{
class TableB:
big_table = models.ForeignKey(BigTable, related_name='...')
item_id = models.CharField(max_length=1024)
}}}
> I'm not certain whether or not your proposed changes are correct. If you
can provide a patch so we can check whether or not it breaks existing
behavior, it'll be more easily to evaluate the idea.
Neither are we. Maybe, a {{{UNION}}} could also work. The real issue we
have is the slow execution of the original query.
--
Ticket URL: <https://code.djangoproject.com/ticket/27260#comment:2>
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