analytics: Add indexes to optimize performance of aggregation.

These indexes fix some slow queries used in updating the analytics
tables, resulting in the analytics system consuming far less total
resources.

analytics/migrations/0008_add_count_indexes.py

@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.5 on 2017-02-01 22:28
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('zerver', '0050_userprofile_avatar_version'),
+        ('analytics', '0007_remove_interval'),
+    ]
+
+    operations = [
+        migrations.AlterIndexTogether(
+            name='realmcount',
+            index_together=set([('property', 'end_time')]),
+        ),
+        migrations.AlterIndexTogether(
+            name='streamcount',
+            index_together=set([('property', 'realm', 'end_time')]),
+        ),
+        migrations.AlterIndexTogether(
+            name='usercount',
+            index_together=set([('property', 'realm', 'end_time')]),
+        ),
+    ]

analytics/models.py

@@ -86,6 +86,7 @@ class RealmCount(BaseCount):
 
     class Meta(object):
         unique_together = ("realm", "property", "subgroup", "end_time")
+        index_together = ["property", "end_time"]
 
     @staticmethod
     def extended_id():
@@ -107,6 +108,9 @@ class UserCount(BaseCount):
 
     class Meta(object):
         unique_together = ("user", "property", "subgroup", "end_time")
+        # This index dramatically improves the performance of
+        # aggregating from users to realms
+        index_together = ["property", "realm", "end_time"]
 
     @staticmethod
     def extended_id():
@@ -128,6 +132,9 @@ class StreamCount(BaseCount):
 
     class Meta(object):
         unique_together = ("stream", "property", "subgroup", "end_time")
+        # This index dramatically improves the performance of
+        # aggregating from streams to realms
+        index_together = ["property", "realm", "end_time"]
 
     @staticmethod
     def extended_id():