#34538: Incorrect query generated with on subquery WHERE depending on the order
of
the Q() objects
-------------------------------------+-------------------------------------
Reporter: Alex | Owner: nobody
Type: Bug | Status: closed
Component: Database layer | Version: 4.2
(models, ORM) |
Severity: Normal | Resolution: duplicate
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Hana Burtin):
Looks like the issue is the priorities of operators in postgres:
{{{
postgres=# select false and false or true;
?column?
t
}}}
{{{
postgres=# select false and true or false;
?column?
f
}}}
And I think we are expecting the same operation priority as python:
{{{
>>> 1 & 0 | 1
<<< 1
>>> 1 & 1 | 0
<<< 1
}}}
To make things simpler: in python OR operators (`|` and `or`) are
evaluated before AND operators (`&` and `and`), while for postgres they
have the same priority order.
To solve this issue and similar ones, we might want to always add brackets
around `OR` operator.
--
Ticket URL: <https://code.djangoproject.com/ticket/34538#comment:4>
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