diff --git a/app/models/bulletin.rb b/app/models/bulletin.rb
index bb3eec9..b752a89 100644
--- a/app/models/bulletin.rb
+++ b/app/models/bulletin.rb
@@ -85,6 +85,8 @@ class Bulletin
   scope :filter_cats_and_tags, ->(cats,tags) {filter_by_widget_categories(cats,false).filter_by_tags(tags)}
   before_create :set_expire
   before_save :check_limit
+  index({postdate: 1}, { unique: false, background: true })
+  index({is_top: -1,postdate: -1, _id: -1}, { unique: false, background: true })
   def to_calendar_param
     self.to_param
   end