Remove ORDER BY from count subquery

rafaelsales · rafaelsales · commit 6fd65f2ace35 · 2018-04-03T01:58:29.000-03:00
Queries like `SELECT COUNT(*) FROM (SELECT DISTINCT resources.* FROM resources ORDER BY resources.created_at DESC LIMIT 1 OFFSET 30) subquery_for_count`
are too inefficient
diff --git a/lib/active_admin/resource_controller/decorators.rb b/lib/active_admin/resource_controller/decorators.rb
@@ -68,7 +68,7 @@ def self.wrap!(parent, name)
           ::Class.new parent do
             delegate :reorder, :page, :current_page, :total_pages, :limit_value,
                      :total_count, :offset, :to_key, :group_values, :except,
-                     :find_each, :ransack
+                     :reorder, :find_each, :ransack
 
             define_singleton_method(:name) { name }
           end
diff --git a/lib/active_admin/views/components/paginated_collection.rb b/lib/active_admin/views/components/paginated_collection.rb
@@ -102,7 +102,7 @@ def build_pagination
           # you pass in the :total_pages option. We issue a query to determine
           # if there is another page or not, but the limit/offset make this
           # query fast.
-          offset = collection.offset(collection.current_page * @per_page.to_i).limit(1).count
+          offset = collection.reorder(nil).offset(collection.current_page * @per_page.to_i).limit(1).count
           options[:total_pages] = collection.current_page + offset
           options[:right] = 0
         end
