On Tue, Nov 1, 2011 at 6:19 PM, christian.oudard <christian.oud...@gmail.com
> wrote:
> I am doing a very simple aggregation using the Django ORM, and it is
> producing a GROUP BY clause that includes the data field, which is
> very large, and is slowing down the query by over 100-fold.
>
> Here is a simplified version of the model:
>
> class Document(models.Model):
> data = models.TextField()
>
> class Attachment(models.Model):
> document = models.ForeignKey(Document)
>
> And the query I am running:
>
> Document.objects.annotate(num_attachments=Count('attachment'))
>
>
The SQL generated by the ORM for this query changed between Django version
1.2 and 1.3. The 1.2 SQL did a group by only on the id field. With 1.3
we're getting id twice and then all other fields in the model. Bisection
shows the change was made with r14715:
https://code.djangoproject.com/changeset/14715
It certainly looks to me like the old SQL was correct and preferable for
this particular case. In a brief search I did not find a ticket reporting
this issue -- could you open one?
Karen
--
http://tracey.org/kmt/
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