#29794: Duplicate object returned using filter
-------------------------------------+-------------------------------------
     Reporter:  Lars Solberg         |                    Owner:  nobody
         Type:  Bug                  |                   Status:  closed
    Component:  Database layer       |                  Version:  2.1
  (models, ORM)                      |
     Severity:  Normal               |               Resolution:  invalid
     Keywords:  duplicate, vacuum    |             Triage Stage:
                                     |  Unreviewed
    Has patch:  0                    |      Needs documentation:  0
  Needs tests:  0                    |  Patch needs improvement:  0
Easy pickings:  0                    |                    UI/UX:  0
-------------------------------------+-------------------------------------
Changes (by Claude Paroz):

 * status:  new => closed
 * resolution:   => invalid


Comment:

 Sorry, but I don't see anything shocking in what you showed us, even if
 it's a bit surprising.

 For example:
 {{{
 In [6]: Server.objects.filter(name='server1').order_by('-name')[0].pk
 Out[6]: 2

 In [7]: Server.objects.filter(name='server1').order_by('-name')[1].pk
 Out[7]: 2
 }}}

 You are doing two queries with undefined ordering (as `name` is
 identical). So it's totally possible that the first query returns pk [1,
 2], while the second query returns [2, 1].

 It would be shocking if you'd obtain a similar result with one unique
 queryset:
 {{{
 qs = Server.objects.filter(name='server1').order_by('-name')
 qs[0].pk => 2
 qs[1].pk => 2
 }}}

-- 
Ticket URL: <https://code.djangoproject.com/ticket/29794#comment:1>
Django <https://code.djangoproject.com/>
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