1 files changed, 3 insertions, 24 deletions
diff --git a/lib/gitlab/sql/union.rb b/lib/gitlab/sql/union.rb
index b15f2ca385a..7fb3487a5e5 100644
--- a/lib/gitlab/sql/union.rb
+++ b/lib/gitlab/sql/union.rb
@@ -13,30 +13,9 @@ module Gitlab
     #     sql   = union.to_sql
     #
     #     Project.where("id IN (#{sql})")
-    class Union
-      def initialize(relations, remove_duplicates: true)
-        @relations = relations
-        @remove_duplicates = remove_duplicates
-      end
-
-      def to_sql
-        # Some relations may include placeholders for prepared statements, these
-        # aren't incremented properly when joining relations together this way.
-        # By using "unprepared_statements" we remove the usage of placeholders
-        # (thus fixing this problem), at a slight performance cost.
-        fragments = ActiveRecord::Base.connection.unprepared_statement do
-          @relations.map { |rel| rel.reorder(nil).to_sql }.reject(&:blank?)
-        end
-
-        if fragments.any?
-          "(" + fragments.join(")\n#{union_keyword}\n(") + ")"
-        else
-          'NULL'
-        end
-      end
-
-      def union_keyword
-        @remove_duplicates ? 'UNION' : 'UNION ALL'
+    class Union < SetOperator
+      def self.operator_keyword
+        'UNION'
       end
     end
   end