diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/ref/models/expressions.txt | 31 | ||||
| -rw-r--r-- | docs/releases/4.2.txt | 4 |
2 files changed, 28 insertions, 7 deletions
diff --git a/docs/ref/models/expressions.txt b/docs/ref/models/expressions.txt index 25edd1f3e8..95f093e2a3 100644 --- a/docs/ref/models/expressions.txt +++ b/docs/ref/models/expressions.txt @@ -741,12 +741,6 @@ instead they are part of the selected columns. .. class:: Window(expression, partition_by=None, order_by=None, frame=None, output_field=None) - .. attribute:: filterable - - Defaults to ``False``. The SQL standard disallows referencing window - functions in the ``WHERE`` clause and Django raises an exception when - constructing a ``QuerySet`` that would do that. - .. attribute:: template Defaults to ``%(expression)s OVER (%(window)s)'``. If only the @@ -819,6 +813,31 @@ to reduce repetition:: >>> ), >>> ) +Filtering against window functions is supported as long as lookups are not +disjunctive (not using ``OR`` or ``XOR`` as a connector) and against a queryset +performing aggregation. + +For example, a query that relies on aggregation and has an ``OR``-ed filter +against a window function and a field is not supported. Applying combined +predicates post-aggregation could cause rows that would normally be excluded +from groups to be included:: + + >>> qs = Movie.objects.annotate( + >>> category_rank=Window( + >>> Rank(), partition_by='category', order_by='-rating' + >>> ), + >>> scenes_count=Count('actors'), + >>> ).filter( + >>> Q(category_rank__lte=3) | Q(title__contains='Batman') + >>> ) + >>> list(qs) + NotImplementedError: Heterogeneous disjunctive predicates against window functions + are not implemented when performing conditional aggregation. + +.. versionchanged:: 4.2 + + Support for filtering against window functions was added. + Among Django's built-in database backends, MySQL 8.0.2+, PostgreSQL, and Oracle support window expressions. Support for different window expression features varies among the different databases. For example, the options in diff --git a/docs/releases/4.2.txt b/docs/releases/4.2.txt index cb64750009..ed00ee1350 100644 --- a/docs/releases/4.2.txt +++ b/docs/releases/4.2.txt @@ -189,7 +189,9 @@ Migrations Models ~~~~~~ -* ... +* ``QuerySet`` now extensively supports filtering against + :ref:`window-functions` with the exception of disjunctive filter lookups + against window functions when performing aggregation. Requests and Responses ~~~~~~~~~~~~~~~~~~~~~~ |