From f0be2cb19274bb6029f84ca274a72c4d7fbee2d3 Mon Sep 17 00:00:00 2001 From: Prem Sichanugrist Date: Thu, 20 Oct 2011 17:15:28 -0400 Subject: Add some note on adding index to HABTM table --- activerecord/lib/active_record/associations.rb | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'activerecord/lib/active_record/associations.rb') diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb index 2449df079a..34684ad2f5 100644 --- a/activerecord/lib/active_record/associations.rb +++ b/activerecord/lib/active_record/associations.rb @@ -1432,6 +1432,10 @@ module ActiveRecord # end # end # + # It's also a good idea to add indexes to each of those columns to speed up the joins process. + # However, in MySQL it is advised to add a compound index for both of the columns as MySQL only + # uses one index per table during the lookup. + # # Adds the following methods for retrieval and query: # # [collection(force_reload = false)] -- cgit v1.2.3