#34659: mysql backend creates queries using CONVERT_TZ even when this is not
supported
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Reporter: Klaas van Schelven | Owner: nobody
Type: Uncategorized | Status: new
Component: Uncategorized | Version: 4.2
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Description changed by Klaas van Schelven:
Old description:
> To test whether a mysql server has the zoneinfo database loaded (feature
> name: `has_zoneinfo_database`), the
> [https://github.com/django/django/blob/1fe0b167af3611cca79e8a8092ee929312193c6f/django/db/backends/mysql/base.py#L410
> following code] 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
> [https://github.com/django/django/blob/main/django/db/backends/mysql/operations.py#L94
> generating sql], despite the fact that the generated sql contains
> something that we know will evaluate to `NULL`, namely, the very same
> `CONVERT_TZ` mentioned in the above.
>
> This shows up when filtering like so:
>
> {{{
> Foo.objects(some_datetimefield__date="2023-06-16")
> }}}
>
> which evaluates to the empty queryset, despite there being such objects.
> On a mysql database without the zoneinfo database loaden, and with
> `USE_TZ = True`, obviously
New description:
To test whether a mysql server has the zoneinfo database loaded (feature
name: `has_zoneinfo_database`), the
[https://github.com/django/django/blob/1fe0b167af3611cca79e8a8092ee929312193c6f/django/db/backends/mysql/base.py#L410
following code] 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
[https://github.com/django/django/blob/main/django/db/backends/mysql/operations.py#L94
generating sql], despite the fact that the generated sql contains
something that we know will evaluate to `NULL`, namely, the very same
`CONVERT_TZ` mentioned in the above.
This shows up when filtering like so:
{{{
Foo.objects(some_datetimefield__date="2023-06-16")
}}}
which evaluates to the empty queryset, despite there being such objects.
On a mysql database without the zoneinfo database loaded, and with `USE_TZ
= True`, obviously
--
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Ticket URL: <https://code.djangoproject.com/ticket/34659#comment:6>
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