#33655: Unnecessary column in a GROUP BY clause with QuerySet.exists()
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Reporter: Marc Perrin | Owner: Marc
Type: | Perrin
Cleanup/optimization | Status: assigned
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 Mariusz Felisiak):
Replying to [comment:8 Marc Perrin]:
> Yeah, I guess I can do that, with Simon's suggestion the whole thing
should be straightforward enough.
> I'll take the ticket - I'll have to look up the contribution guide etc.
/ especially about the tests, as I haven't really contributed before.
Great, thanks! In this ticket we are forced to check a generated SQL, IMO
it's fine to add assertions to an existing test e.g.
`aggregation.tests.AggregateTestCase.test_aggregation_subquery_annotation_exists`:
{{{#!python
with self.assertNumQueries(1) as ctx:
self.assertTrue(publisher_qs.exists())
sql = ctx[0]["sql"]
self.assertIn("SELECT 1 ", sql)
self.assertNotIn("(1)", sql)
# There is just one GROUP BY clause (zero commas means at most one
# clause).
self.assertEqual(sql[sql.index("GROUP BY") :].count(", "), 0)
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/33655#comment:10>
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