id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
12560	Unique validation should not check for null atuo-assigned PK	Karen Tracey	nobody	"Initially noted here: http://groups.google.com/group/django-developers/browse_thread/thread/b45c4d599ea93b74#

The model validation unique check code is issuing an unnecessary query when adding new instances of models with auto-assigned PKs:

{{{
Python 2.5.2 (r252:60911, Oct  5 2008, 19:24:49) 
[GCC 4.3.2] on linux2
Type ""help"", ""copyright"", ""credits"" or ""license"" for more information.
(InteractiveConsole)
>>> import django
>>> django.get_version()
u'1.2 alpha 1 SVN-12120'
>>> from ttt.models import Tag
>>> from django import forms
>>> class TagForm(forms.ModelForm):
...     class Meta:
...         model = Tag
... 
>>> tf1 = TagForm({'name': 'T1'})
>>> tf1.is_valid()
True
>>> from django.db import connection
>>> connection.queries
[{'time': '0.002', 'sql': u'SELECT (1) AS `a`, `ttt_tag`.`id`, `ttt_tag`.`name` FROM `ttt_tag` WHERE `ttt_tag`.`id` IS NULL LIMIT 1'}]
>>> 
}}}

Besides being unnecessary, that's a query that will potentially return an unexpected result on MySQL, see: http://groups.google.com/group/django-developers/browse_thread/thread/d4180b8addf5e970/

This is similar to #12132, only for adding new instances instead of changing existing ones."		closed	Uncategorized	dev		fixed			Unreviewed	1	0	0	0	0	0