loading notifications raise OperationalError MySQL join limit

Hi,

during my development after couple dozens of notification suddenly I was getting this exception. Have you ever met with this problem?

Method: GET
Request URL: http://localhost:8000/backend/estates/tour/

Django Version: 1.9.6
Python Version: 2.7.11


Template error:
In template /home/truhlik/Dropbox/web/reality/templates/base_list.html, error at line 0
   1116   1 : {% extends request.is_ajax|yesno:"base_ajax.html,base.html" %}
   2 : 
   3 : {% load i18n permissions django_tables2 common_tags %}
   4 : 
   5 : {% block body %}
   6 :     {% render_table list_table %}
   7 : {% endblock %}

Traceback:

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  174.                     response = self.process_exception_by_middleware(e, request)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  172.                     response = response.render()

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/response.py" in render
  160.             self.content = self.rendered_content

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/response.py" in rendered_content
  137.         content = template.render(context, self._request)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/backends/django.py" in render
  95.             return self.template.render(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/base.py" in render
  206.                     return self._render(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/base.py" in _render
  197.         return self.nodelist.render(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/base.py" in render
  992.                 bit = node.render_annotated(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/base.py" in render_annotated
  959.             return self.render(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/loader_tags.py" in render
  173.         return compiled_parent._render(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/base.py" in _render
  197.         return self.nodelist.render(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/base.py" in render
  992.                 bit = node.render_annotated(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/base.py" in render_annotated
  959.             return self.render(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/loader_tags.py" in render
  69.                 result = block.nodelist.render(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/base.py" in render
  992.                 bit = node.render_annotated(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/template/base.py" in render_annotated
  959.             return self.render(context)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/notify/templatetags/notification_tags.py" in render
  150.                 return self.generate_html(notifications)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/notify/templatetags/notification_tags.py" in generate_html
  48.         for nf in notifications:

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/models/query.py" in __iter__
  258.         self._fetch_all()

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/notify/models.py" in _fetch_all
  36.                 prefetch_relations(self)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/notify/utils.py" in prefetch_relations
  102.         models = prefetch_relations(model_class.objects.filter(pk__in=object_ids).select_related())

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/notify/utils.py" in prefetch_relations
  86.     for weak_model in weak_queryset:

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/models/query.py" in __iter__
  258.         self._fetch_all()

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/models/query.py" in _fetch_all
  1074.             self._result_cache = list(self.iterator())

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/models/query.py" in __iter__
  52.         results = compiler.execute_sql()

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in execute_sql
  848.             cursor.execute(sql, params)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/backends/utils.py" in execute
  79.             return super(CursorDebugWrapper, self).execute(sql, params)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/backends/utils.py" in execute
  64.                 return self.cursor.execute(sql, params)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/utils.py" in __exit__
  95.                 six.reraise(dj_exc_type, dj_exc_value, traceback)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/backends/utils.py" in execute
  64.                 return self.cursor.execute(sql, params)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/django/db/backends/mysql/base.py" in execute
  112.             return self.cursor.execute(query, args)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/MySQLdb/cursors.py" in execute
  205.             self.errorhandler(self, exc, value)

File "/home/truhlik/.virtualenvs/reality/local/lib/python2.7/site-packages/MySQLdb/connections.py" in defaulterrorhandler
  36.     raise errorclass, errorvalue

Exception Type: OperationalError at /backend/estates/tour/
Exception Value: (1116, 'Too many tables; MySQL can only use 61 tables in a join')

[truhlik]

Great thank you. Let me know if I can help you with anything.

[v1k45]

I think a simple switch for turning off prefetchs will do. I’ll push a fix as soon as i get time.

PS: ignore the old comment, I didn’t read your comment completely.