Inefficient query produced when using OR'ed Q objects

[Tom Forbes]

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.