#29771: Support database-specific syntax for bulk_update
-------------------------------------+-------------------------------------
Reporter: Tom Forbes | Owner: Tom
Type: | Forbes
Cleanup/optimization | Status: assigned
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Changes (by Tom Forbes):
* cc: Tom Forbes (added)
Comment:
I think the groundwork to this is quite difficult to lay. The current
`SQLUpdateCompiler` is not suitable for this, I think.
Also I believe we can mimic this on SQLLite:
{{{
WITH test(id) AS (SELECT 1 UNION ALL SELECT 2)
UPDATE demo
SET name=(select id from test where id=demo.id)
WHERE id IN (select id from test)
}}}
Whether or not this is faster is something I'm not sure of. I believe the
MySQL syntax will be faster, and there is no SQL standard way of doing
this (I believe?), so we are left with a number of pretty different
workarounds. I'm not sure how to structure this nicely.
I can maybe hack Postgres support into the SQLUpdateCompiler, but it's
really not nice. We have to create all the aliases ourselves, manage the
different column names, etc etc.
--
Ticket URL: <https://code.djangoproject.com/ticket/29771#comment:3>
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