#16759: Expensive sql.Query cloning
-------------------------------------+-------------------------------------
Reporter: Suor | Owner: Suor
Type: Bug | Status: closed
Component: Database layer | Version: 1.3
(models, ORM) | Resolution: fixed
Severity: Normal | Triage Stage: Ready for
Keywords: orm performance | checkin
cloning | Needs documentation: 0
Has patch: 1 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
-------------------------------------+-------------------------------------
Changes (by Anssi Kääriäinen <akaariai@…>):
* status: new => closed
* resolution: => fixed
Comment:
In [changeset:"23ca3a01940c63942885df4709712cebf4df79ec"]:
{{{
#!CommitTicketReference repository=""
revision="23ca3a01940c63942885df4709712cebf4df79ec"
Fixed #16759 -- Remove use of __deepcopy__ in qs.clone()
The original problem was that queryset cloning was really expensive
when filtering with F() clauses. The __deepcopy__ went too deep copying
_meta attributes of the models used. To fix this the use of
__deepcopy__ in qs cloning was removed.
This commit results in some speed improvements across the djangobench
benchmark suite. Most query_* tests are 20-30% faster, save() is 50%
faster and finally complex filtering situations can see 2x to order
of magnitude improvments.
Thanks to Suor, Alex and lrekucki for valuable feedback.
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/16759#comment:36>
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