PERF: reverse index on topic users to speed up join

discourse · Sep 10, 2014 · af75360 · af75360
1 parent ca2100d
commit af75360
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/db/migrate/20140910130155_create_topic_user_index.rb b/db/migrate/20140910130155_create_topic_user_index.rb
@@ -0,0 +1,6 @@
+class CreateTopicUserIndex < ActiveRecord::Migration
+  def change
+    # seems to be the most effective for joining into topics
+    add_index :topic_users, [:user_id, :topic_id], unique: true
+  end
+end