#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.
--
Ticket URL: <https://code.djangoproject.com/ticket/25789#comment:7>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/067.de37d52893e5e1c2b46b51c6527f126f%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.
