#34538: Incorrect query generated with on subquery WHERE depending on the order
of
the Q() objects
-------------------------------------+-------------------------------------
Reporter: Alex | Owner: nobody
Type: Bug | Status: new
Component: Database | Version: 4.2
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
I have reproduced this error on
Django 4.1.9 and Mysql 5.7.
Django 4.2.1 and Mysql 8.0, Postgres 14.1 and Sqlite 3.
Models:
{{{
#!python
from django.db import models
class Child(models.Model):
pass
class ParentLink(models.Model):
enabled = models.BooleanField(db_index=True)
class ChildLink(models.Model):
enabled = models.BooleanField(db_index=True)
origin_child = models.ForeignKey(
Child,
on_delete=models.PROTECT,
related_name='origin_children',
)
parent_link = models.ForeignKey(
ParentLink,
on_delete=models.PROTECT,
related_name='child_links',
)
}}}
Data
{{{
#!python
Child.objects.create(id=1)
Child.objects.create(id=2)
ParentLink.objects.create(id=1, enabled=True)
ParentLink.objects.create(id=2, enabled=True)
ChildLink.objects.create(id=1, enabled=True, origin_child_id=1,
parent_link_id=1)
ChildLink.objects.create(id=2, enabled=True, origin_child_id=2,
parent_link_id=2)
ChildLink.objects.create(id=3, enabled=True, origin_child_id=2,
parent_link_id=1)
ChildLink.objects.create(id=4, enabled=True, origin_child_id=1,
parent_link_id=2)
}}}
This code generates the correct SQL query and returns the correct results
(0 results for the test data)
{{{
#!python
(
ParentLink.objects
.filter(
~Q(child_links__origin_child_id=1) |
Q(child_links__origin_child_id=1, child_links__enabled=False),
enabled=True
)
)
}}}
SQL query generated in Postgres
{{{
#!sql
SELECT "testquery_parentlink"."id", "testquery_parentlink"."enabled" FROM
"testquery_parentlink" LEFT OUTER JOIN "testquery_childlink" ON
("testquery_parentlink"."id" = "testquery_childlink"."parent_link_id")
WHERE ((NOT (EXISTS(SELECT 1 AS "a" FROM "testquery_childlink" U1 WHERE
(U1."origin_child_id" = 1 AND U1."parent_link_id" =
("testquery_parentlink"."id")) LIMIT 1)) OR (NOT
"testquery_childlink"."enabled" AND
"testquery_childlink"."origin_child_id" = 1)) AND
"testquery_parentlink"."enabled")
}}}
This one returns incorrect results (Returns both ParentLinks in the test
data)
{{{
#!python
(
ParentLink.objects
.filter(
Q(child_links__origin_child_id=1, child_links__enabled=False) |
~Q(child_links__origin_child_id=1),
enabled=True
)
)
}}}
SQL query generated in Postgres
{{{
#!sql
SELECT "testquery_parentlink"."id", "testquery_parentlink"."enabled" FROM
"testquery_parentlink" LEFT OUTER JOIN "testquery_childlink" ON
("testquery_parentlink"."id" = "testquery_childlink"."parent_link_id")
WHERE (((NOT "testquery_childlink"."enabled" AND
"testquery_childlink"."origin_child_id" = 1) OR NOT (EXISTS(SELECT 1 AS
"a" FROM "testquery_childlink" U1 WHERE (U1."origin_child_id" = 1 AND
U1."id" = ("testquery_childlink"."id") AND
"testquery_childlink"."parent_link_id" = ("testquery_parentlink"."id"))
LIMIT 1))) AND "testquery_parentlink"."enabled")
}}}
The WHERE in the subquery in the second case is incorrect.
--
Ticket URL: <https://code.djangoproject.com/ticket/34538>
Django <https://code.djangoproject.com/>
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