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Make less DB queries (particularly in the Forum)

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Skia
2017-05-14 04:36:04 +02:00
parent 862a4619b3
commit 23fe797a9e
2 changed files with 17 additions and 3 deletions
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13
forum/models.py
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@ -136,10 +136,19 @@ class Forum(models.Model):
def last_message(self):
return self.get_last_message()
forum_list = {} # Class variable used for cache purpose
def get_last_message(self):
last_msg = None
for m in ForumMessage.objects.select_related('topic__forum', 'author').order_by('-id'):
forum = m.topic.forum
for m in ForumMessage.objects.select_related('topic__forum').order_by('-id'):
if m.topic.forum.id in Forum.forum_list.keys(): # The object is already in Python's memory,
# so there's no need to query it again
forum = Forum.forum_list[m.topic.forum.id]
else: # Query the forum object and store it in the class variable for further use.
# Keeping the same object allows the @cached_property to work properly.
# This trick divided by 4 the number of DB queries in the main forum page, and about the same on many other forum pages.
# This also divided by 4 the amount of CPU usage for thoses pages, according to Django Debug Toolbar.
forum = m.topic.forum
Forum.forum_list[forum.id] = forum
if self in (forum.parent_list + [forum]) and not m.deleted:
return m