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PODjango - consecutive dumpdata calls fail, even though work correctly when run separately
 

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  1. PODjango - consecutive dumpdata calls fail, even though work correctly when run separately
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    <p>I've run into an issue trying to set up automatic backups on my site. The problem boils down to the following.</p> <p>I open the Python shell and I call the dumpdata command twice. It <strong>works</strong> for the first time and it returns <strong>empty list</strong> the second time. After that all further dumpdata calls return empty list:</p> <pre><code>&gt;&gt;&gt; python manage.py shell &gt;&gt;&gt; from django.core.management import call_command &gt;&gt;&gt; call_command("dumpdata") [{"pk": 1, (...) // lots of data // &gt;&gt;&gt; call_command("dumpdata") &gt;&gt;&gt; [] </code></pre> <p>To make it work again I need to restart the python shell.</p> <p>Edit: I use Django 1.4 and Python 2.6</p> <p>Edit2: My current hypothesis is that the problem is related to this issue: <a href="https://code.djangoproject.com/ticket/5423" rel="nofollow">https://code.djangoproject.com/ticket/5423</a> - identified 5 years ago and according to Django 1.5 release notes, to-be resolved in the next release. Does anybody have an idea how to workaround this issue without altering the 1.4 framework code being run on the machine?</p> <p>Edit3: However sql dump of the whole database is only 0.5 MB, which makes it rather unprobable that the serialization is running out of memory. And anyway, wouldn't I get an explicit error in such case?</p> <p>Edit4: Mystery solved. As Tomasz Gandor correctly determined, the problem was that shell executes the commands in one transaction, and after one of the commands causes DBError, further DB calls are ignored, as described here: <a href="https://code.djangoproject.com/ticket/10813" rel="nofollow">https://code.djangoproject.com/ticket/10813</a> . Why the DB error during the first dumpdata wasn't explicitely reported remains a mystery to me.</p>
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    1. USPrzemysław Pietrzkiewicz
    1. USPrzemysław Pietrzkiewicz
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    1. COI've made a simple test and works fine for me. What type of database do you use? Also which Django/Python versions?
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      1. USTisho
    2. CODjango 1.4 and Python 2.6. I suspect the problem is data-dependent, as it does not occur on my local machine, where I have different db content (less data in general).
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      1. PODjango - consecutive dumpdata calls fail, even though work correctly when run separately
      1. USPrzemysław Pietrzkiewicz
    3. CO"I used this patch and changed model.objects.all() to model.objects.iterator() in django/core/management/commands/dumpdata.py. After that I was successfully able to dump a considerably big database (1Gb SQLite file). Python process resident memory size was at about 20M all the time" (in your refered page)
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      1. USdani herrera
 

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