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Refs #28333 -- Added partial support for filtering against window functions.

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Adds support for joint predicates against window annotations through
subquery wrapping while maintaining errors for disjointed filter
attempts.

The "qualify" wording was used to refer to predicates against window
annotations as it's the name of a specialized Snowflake extension to
SQL that is to window functions what HAVING is to aggregates.

While not complete the implementation should cover most of the common
use cases for filtering against window functions without requiring
the complex subquery pushdown and predicate re-aliasing machinery to
deal with disjointed predicates against columns, aggregates, and window
functions.

A complete disjointed filtering implementation should likely be
deferred until proper QUALIFY support lands or the ORM gains a proper
subquery pushdown interface.
This commit is contained in:
Simon Charette 2022-08-10 08:22:01 -04:00 • committed by Mariusz Felisiak
parent f3f9d03edf
commit f387d024fc
9 changed files with 489 additions and 67 deletions
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15
django/db/models/expressions.py
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@ -836,6 +836,7 @@ class ResolvedOuterRef(F):
"""
contains_aggregate = False
contains_over_clause = False
def as_sql(self, *args, **kwargs):
raise ValueError(
@ -1210,6 +1211,12 @@ class OrderByList(Func):
return "", ()
return super().as_sql(*args, **kwargs)
def get_group_by_cols(self):
group_by_cols = []
for order_by in self.get_source_expressions():
group_by_cols.extend(order_by.get_group_by_cols())
return group_by_cols
@deconstructible(path="django.db.models.ExpressionWrapper")
class ExpressionWrapper(SQLiteNumericMixin, Expression):
@ -1631,7 +1638,6 @@ class Window(SQLiteNumericMixin, Expression):
# be introduced in the query as a result is not desired.
contains_aggregate = False
contains_over_clause = True
filterable = False
def __init__(
self,
@ -1733,7 +1739,12 @@ class Window(SQLiteNumericMixin, Expression):
return "<%s: %s>" % (self.__class__.__name__, self)
def get_group_by_cols(self, alias=None):
return []
group_by_cols = []
if self.partition_by:
group_by_cols.extend(self.partition_by.get_group_by_cols())
if self.order_by is not None:
group_by_cols.extend(self.order_by.get_group_by_cols())
return group_by_cols
class WindowFrame(Expression):