1 files changed, 37 insertions, 0 deletions
diff --git a/db/migrate/20170727123534_add_index_on_events_project_id_id.rb b/db/migrate/20170727123534_add_index_on_events_project_id_id.rb
new file mode 100644
index 00000000000..1c4aaaf9dd6
--- /dev/null
+++ b/db/migrate/20170727123534_add_index_on_events_project_id_id.rb
@@ -0,0 +1,37 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddIndexOnEventsProjectIdId < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  COLUMNS = %i[project_id id].freeze
+  TABLES = %i[events events_for_migration].freeze
+
+  disable_ddl_transaction!
+
+  def up
+    TABLES.each do |table|
+      add_concurrent_index(table, COLUMNS) unless index_exists?(table, COLUMNS)
+
+      # We remove the index _after_ adding the new one since MySQL doesn't let
+      # you remove an index when a foreign key exists for the same column.
+      if index_exists?(table, :project_id)
+        remove_concurrent_index(table, :project_id)
+      end
+    end
+  end
+
+  def down
+    TABLES.each do |table|
+      unless index_exists?(table, :project_id)
+        add_concurrent_index(table, :project_id)
+      end
+
+      unless index_exists?(table, COLUMNS)
+        remove_concurrent_index(table, COLUMNS)
+      end
+    end
+  end
+end