Opened 18 months ago

Last modified 17 months ago

#34659 closed Uncategorized

mysql backend creates queries using CONVERT_TZ even when this is not supported — at Initial Version

Reported by: Klaas van Schelven Owned by: nobody
Component: Database layer (models, ORM) Version: 4.2
Severity: Normal Keywords:
Cc: Triage Stage: Unreviewed
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description

To test whether a mysql server has the zoninfo database loaded (feature name: has_zoneinfo_database), the [following code](https://github.com/django/django/blob/1fe0b167af3611cca79e8a8092ee929312193c6f/django/db/backends/mysql/base.py#L410) is run:

`
CONVERT_TZ('2001-01-01 01:00:00', 'UTC', 'UTC') IS NOT NULL
`

However, this test is not actually used (i.e. there is no condition on the feature being True) when [generating sql](https://github.com/django/django/blob/main/django/db/backends/mysql/operations.py#L94), despite the fact that the generated sql contains something that we know will evaluate to NULL

This shows up when filtering like so:

`
Foo.objects(some_datetimefielddate="2023-06-16")
`
which evaluates to the empty queryset, despite there being such objects. USE_TZ = True, obviously

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