IntegrityError: duplicate key value violates unique constraint "djapian_change_content_type_id_key"

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Has anyone any ideas?

In our project we are using django with postgresql and receive "sometimes"
the following error:

IntegrityError: duplicate key value violates unique constraint
"djapian_change_content_type_id_key"

Is it possible to deactivate the "autoupdate" functionality? Or how can we
solve this problem?

Here our traceback:

  File "/usr/local/lib/python2.6/dist-packages/django/db/models/base.py",
line 410, in save
    self.save_base(force_insert=force_insert, force_update=force_update)

  File "/usr/local/lib/python2.6/dist-packages/django/db/models/base.py",
line 506, in save_base
    created=(not record_exists), raw=raw)

  File
"/usr/local/lib/python2.6/dist-packages/django/dispatch/dispatcher.py",
line 166, in send
    response = receiver(signal=self, sender=sender, **named)

  File
"/usr/local/lib/python2.6/dist-packages/Djapian-2.3-py2.6.egg/djapian/signals.py
",
line 8, in post_save
    Change.objects.create(object=instance, action= created and "add" or "edit")

  File
"/usr/local/lib/python2.6/dist-packages/Djapian-2.3-py2.6.egg/djapian/models.py"
,
line 32, in create
    old_change.save()

  File
"/usr/local/lib/python2.6/dist-packages/Djapian-2.3-py2.6.egg/djapian/models.py"
,
line 65, in save
    super(Change, self).save()

  File "/usr/local/lib/python2.6/dist-packages/django/db/models/base.py",
line 410, in save
    self.save_base(force_insert=force_insert, force_update=force_update)

  File "/usr/local/lib/python2.6/dist-packages/django/db/models/base.py",
line 495, in save_base
    result = manager._insert(values, return_id=update_pk)

  File
"/usr/local/lib/python2.6/dist-packages/django/db/models/manager.py", line
177, in _insert
    return insert_query(self.model, values, **kwargs)

  File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py",
line 1087, in insert_query
    return query.execute_sql(return_id)

  File
"/usr/local/lib/python2.6/dist-packages/django/db/models/sql/subqueries.py", 
line
320, in execute_sql
    cursor = super(InsertQuery, self).execute_sql(None)

  File
"/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py",
line 2369, in execute_sql
    cursor.execute(sql, params)

Thanks, Hans

Original issue reported on code.google.com by braxmeie...@gmail.com on 23 Nov 2009 at 3:09

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To explore more precisely this issue I need concrete information about 
"sometimes" cases.

Original comment by daevaorn on 23 Nov 2009 at 10:25

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Hi daevaorn,

Thanks for your answer...

I'm sorry, but I could not reconstruct the "sometimes" cases. We have a running
webpages and every day while readers visit our pages we receive this error.

Is there an option to deactivate the autoupdate function? For us it would be
sufficient to update the database once a day...

Thx, Hans

Original comment by braxmeie...@gmail.com on 26 Nov 2009 at 8:54

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Hi daevaorn,

Now we found a solution. The problem arises using postgres together with 
djapian. The
problem was a sequence out of sync with its automatically incremented field data
(http://docs.djangoproject.com/en/dev/ref/django-admin/ -> django-admin.py
sqlsequencereset)

Regards, Hans

Original comment by braxmeie...@gmail.com on 5 Dec 2009 at 9:59

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Oh, this is intersting!

How do you think can Djapian do something to prevent such error conditions?

Original comment by daevaorn on 5 Dec 2009 at 10:19

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May be this is an idea?

From http://trac.edgewall.org/ticket/8575

... We add a update_sequence method to the db backend classes, which is much 
like the
get_last_id method. The plugins would be responsible for calling it, but at 
least
there would be a db independent method for it. 

Original comment by braxmeie...@gmail.com on 8 Dec 2009 at 1:47

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Ok. I think this issue is not the Djapian authority.

Original comment by daevaorn on 13 Dec 2009 at 9:08

• Changed state: WontFix

[GoogleCodeExporter]

Update: The IntegrityError "duplicate key value violates unique constraint 
djapian_change_content_type_id_key" is caused, if there are equal search 
requests at 
the same time. That explains why we "received" the error only sometimes. It 
looks like 
there's a problem with postgres transactions and the save method in 
django/djapian.

Original comment by i...@pagewizz.com on 17 Feb 2010 at 12:51

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This looks like a race condition on 
https://code.google.com/p/djapian/source/browse/trunk/src/djapian/models.py#32 
: if multiple saves happen on the same model in parallel, it's possible that 
another thread will create a conflicting Change record in the window between 
the 'get' test returning no results, and the subsequent 'save' on the new 
change object.

Wrapping the 'create' method in a @transaction.commit_on_success decorator (as 
per the attached patch) seems to fix it for me, but I'm damned if I know how to 
write a unit test to reliably replicate this!

Original comment by westdotc...@gmail.com on 17 Apr 2013 at 10:05

Attachments:

• djapian-issue97-transaction.patch