#25789: Inefficient Queries Generated due to not using WHERE EXISTS
-------------------------------------+-------------------------------------
Reporter: Alex Rothberg | Owner: nobody
Type: | Status: new
Cleanup/optimization |
Component: Database layer | Version: 1.8
(models, ORM) |
Severity: Normal | Resolution:
Keywords: QuerySet.extra | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by James Howe):
Similarly, I have a use-case where this query structure has the only
acceptable performance (in PostgreSQL):
{{{#!sql
... FROM model_1
WHERE NOT EXISTS (
SELECT TRUE FROM model_2
WHERE model_1.pkey = model_2.fkey
AND (model_2.property IS NULL OR model_2.property >= 42)
)
}}}
Currently using `extra()` to do it.
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Ticket URL: <https://code.djangoproject.com/ticket/25789#comment:7>
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