#33655: Unnecessary column in a GROUP BY clause with QuerySet.exists()
-------------------------------------+-------------------------------------
Reporter: Marc Perrin | Owner: nobody
Type: | Status: new
Cleanup/optimization |
Component: Database layer | Version: 4.0
(models, ORM) |
Severity: Normal | Resolution:
Keywords: exists group by | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Simon Charette):
Maybe we should stop relying on ''extra'' and use `Value(1)` instead
[https://github.com/django/django/blob/ed0a2c3238aa0b9c0d01c436d5bcd70930d696b0/django/db/models/expressions.py#L990-L991
which already disables grouping].
{{{#!diff
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 64e7927f7a..1097de4f79 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -27,6 +27,7 @@
OuterRef,
Ref,
ResolvedOuterRef,
+ Value,
)
from django.db.models.fields import Field
from django.db.models.fields.related_lookups import MultiColSource
@@ -582,8 +583,7 @@ def exists(self, using, limit=True):
q.clear_ordering(force=True)
if limit:
q.set_limits(high=1)
- q.add_extra({"a": 1}, None, None, None, None, None)
- q.set_extra_mask(["a"])
+ q.add_annotation(Value(1), "a")
return q
def has_results(self, using):
}}}
Anything that relies on ''extra'' is a black box to the compiler as it
could be an aggregate function or not.
--
Ticket URL: <https://code.djangoproject.com/ticket/33655#comment:4>
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