#7512: including a nullable foreign key reference in Meta ordering has
unexpected
results
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Reporter: R. Bailey <[EMAIL PROTECTED]> | Owner: gav
Status: new | Milestone: 1.0
Component: Database wrapper | Version: SVN
Resolution: | Keywords:
1.0-blocker
Stage: Accepted | Has_patch: 1
Needs_docs: 0 | Needs_tests: 0
Needs_better_patch: 1 |
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Comment (by mtredinnick):
The fact that one of the tests in `regressiontests/queries/models.py` that
was testing for the absence of outer joins had to be changed to show that
there was a (completely unnecessary) outer join shows that this patch is
doing something wrong. It's not that test that is wrong; it's the
resulting query that is now wrong. We should ''never'' do outer joins
unless they are required. They are much more expensive at the database
side.
Unconditionally promoting joins just because the foreign key can be
nullable is therefore not the way to do this, because you don't need an
outer join unless you care about null values -- not the case when
comparing across a nullable join to a non-null value.
--
Ticket URL: <http://code.djangoproject.com/ticket/7512#comment:9>
Django Code <http://code.djangoproject.com/>
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