#16937: Prefetch related objects
-------------------------------------+-------------------------------------
Reporter: lukeplant | Owner: nobody
Type: New feature | Status: new
Component: Database layer | Version: 1.3
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: | Needs documentation: 0
Has patch: 0 | Patch needs improvement: 1
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
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Comment (by akaariai):
About the concerns of speed and memory usage because of `QuerySet`
caching: I now think that this is not a problem, if in future
prefetch_related will be extended in a way that you can avoid the caching.
For example:
{{{
Book.objects.prefetch_related(R('authors', to_attr='authors_prefetched'))
}}}
Now you will have authors in an ordinary list, accessible in
book.authors_prefetched. This way you will gain the no related manager
memory usage and speed when needed, while in the normal cases you can use
the convenient .prefetch_related('authors') and use the related
manager.all().
That being said, I don't have any problems any more with the extensibility
of the API, or with the implementation where the objects are accessible
through related_manager.all(). Once the patch is updated with the minor
corrections + the dict_join.diff patch I think this will be ready for
commit.
I would like to work already on the custom `QuerySet` / other
extensibility issues so that it could be included already in 1.4. Should I
create a new ticket or is it too early? Or of course if Luke Plant has
plans already for this work I am more than happy just to be a reviewer.
Sorry for being a bit insistent about the extensibility /
related_manager.all() issues. At least there is hope the discussion has
been useful for future work.
--
Ticket URL: <https://code.djangoproject.com/ticket/16937#comment:19>
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