#26434: Inconsistent results of QuerySet.count() when ordering is not a subset
of
explicit grouping.
-------------------------------------+-------------------------------------
Reporter: kamandol | Owner: Michal
| Mládek
Type: Bug | Status: closed
Component: Database layer | Version: dev
(models, ORM) |
Severity: Normal | Resolution: fixed
Keywords: postgresql queryset | Triage Stage: Ready for
count annotate aggreagate | checkin
order_by |
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Mariusz Felisiak):
This caused a [https://djangoci.com/job/django-
oracle/database=oracle19,label=oracle,python=python3.14/lastCompletedBuild/testReport/
regression] on Oracle but not only. `group_by` is a tuple of `Col`
expressions, `order_by` is a list of strings, so `{*self.order_by,
*self.extra_order_by}` will never be a subset of `group_by`.
Previously:
{{{#!sql
SELECT
...
FROM "AGGREGATION_REGRESS_BOOK"
WHERE "AGGREGATION_REGRESS_BOOK"."ID" IN (
SELECT MAX(U0."ID") AS "ID__MAX"
FROM "AGGREGATION_REGRESS_BOOK" U0
GROUP BY U0."CONTACT_ID"
)
ORDER BY "AGGREGATION_REGRESS_BOOK"."ID" ASC
}}}
with this patch
{{{#!sql
SELECT
...
FROM "AGGREGATION_REGRESS_BOOK"
WHERE "AGGREGATION_REGRESS_BOOK"."ID" IN (
SELECT MAX(U0."ID") AS "ID__MAX"
FROM "AGGREGATION_REGRESS_BOOK" U0
GROUP BY U0."CONTACT_ID"
ORDER BY U0."CONTACT_ID" ASC
)
ORDER BY "AGGREGATION_REGRESS_BOOK"."ID" ASC
}}}
As far as I'm aware, we would need to translate string aliases (`order_by`
and `extra_order_by`) to `Col` expressions but this may be expensive here
(or at least non-trivial).
--
Ticket URL: <https://code.djangoproject.com/ticket/26434#comment:29>
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