Optimized tag DB queries

boards/models/tag.py

@@ -1,9 +1,8 b''
 from django.template.loader import render_to_string
 from django.db import models
-from django.db.models import Count, Sum
+from django.db.models import Count
 from django.core.urlresolvers import reverse
 
-from boards.models import Thread
 from boards.models.base import Viewable
 
 
@@ -17,13 +16,8 b' class TagManager(models.Manager):'
         Gets tags that have non-archived threads.
         """
 
-        not_empty_tags = list()
-        tags = self.order_by('-required', 'name')
-        for tag in tags:
-            if tag.get_thread_count() > 0:
-                not_empty_tags.append(tag)
-
-        return not_empty_tags
+        return self.filter(thread__archived=False)\
+            .annotate(num_threads=Count('thread')).filter(num_threads__gt=0)
 
 
 class Tag(models.Model, Viewable):
@@ -54,34 +48,16 b' class Tag(models.Model, Viewable):'
     def get_thread_count(self) -> int:
         return self.get_threads().count()
 
-    def get_post_count(self, archived=False):
-        """
-        Gets posts count for the tag's threads.
-        """
-
-        posts_count = 0
-
-        threads = self.get_threads().filter(archived=archived)
-        if threads.exists():
-            posts_count = threads.annotate(posts_count=Count('replies')) \
-                .aggregate(posts_sum=Sum('posts_count'))['posts_sum']
-
-        if not posts_count:
-            posts_count = 0
-
-        return posts_count
-
     def get_url(self):
         return reverse('tag', kwargs={'tag_name': self.name})
 
     def get_threads(self):
-        return Thread.objects.filter(tags__in=[self]).order_by('-bump_time')
+        return self.thread_set.order_by('-bump_time')
 
     def is_required(self):
         return self.required
 
     def get_view(self):
-        #prefix = '##' if self.is_required() else '#'
         link = '<a class="tag" href="{}">{}</a>'.format(
                 self.get_url(), self.name)
         if self.is_required():