id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
28211	Inefficient query produced when using OR'ed Q objects	Tom Forbes	nobody	"When using OR'ed Q objects in a `.filter()` call Django could be more intelligent about the query it produces.

For example, the following two queries both produce `LEFT OUTER JOIN`:

`SomeModel.objects.filter(Q(related_objects__field=1) | Q(related_objects__other_field=1)`

`SomeModel.objects.filter(Q(related_objects__field=1) | Q())`

In the case of the second query it could be reduced to a `INNER JOIN` as the `OR` is redundant and it is functionally the same as a `.filter(related_objects__field=1)`. 

It is also quite a common pattern to do:

{{{
filters = Q()
if condition:
   filters |= Q(x=1)
if other_condition:
   filters |= Q(y=2)
}}}


And with the current implementation it will always produce a query that assumes `filters` is a valid `OR`. Django should/could be more intelligent and detect if there is only one `OR` condition, and reduce it."	Cleanup/optimization	closed	Database layer (models, ORM)	dev	Normal	fixed			Ready for checkin	1	0	0	0	0	0