#23797: SQL generated for negated F() expressions is incorrect
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Reporter: mssnlayam | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.7
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: | Needs documentation: 0
Has patch: 0 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
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Comment (by akaariai):
After a quick test, it seems the `WHERE ("testapp_rectangle"."length" =
("testapp_rectangle"."width")) IS NOT true` approach will not work that
well. At least PostgreSQL wont use indexes for a query `select * from
foobar where (id > 1 and id < 20) is true`, but will use the index for
`select * from foobar where (id > 1 and id < 20)`. This tells me
PostgreSQL's optimizer will not handle the is true / is not true
conditions well.
If somebody is able to provide a somewhat clean solution to this, I am all
for fixing this.
--
Ticket URL: <https://code.djangoproject.com/ticket/23797#comment:2>
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