Replace Productivity analytics merged_at index

db/migrate/20191101092917_replace_index_on_metrics_merged_at.rb

+# frozen_string_literal: true
+
+class ReplaceIndexOnMetricsMergedAt < ActiveRecord::Migration[5.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :merge_request_metrics, :merged_at
+    remove_concurrent_index :merge_request_metrics, [:merged_at, :id]
+  end
+
+  def down
+    add_concurrent_index :merge_request_metrics, [:merged_at, :id]
+    remove_concurrent_index :merge_request_metrics, :merged_at
+  end
+end

db/post_migrate/20190918104222_schedule_productivity_analytics_backfill.rb

@@ -6,7 +6,7 @@ class ScheduleProductivityAnalyticsBackfill < ActiveRecord::Migration[5.2]
   DOWNTIME = false
 
   def up
-    # no-op since the scheduling times out on GitLab.com
+    # no-op since the migration was removed
   end
 
   def down

db/schema.rb

@@ -2290,7 +2290,7 @@ ActiveRecord::Schema.define(version: 2019_11_05_094625) do
     t.index ["latest_closed_by_id"], name: "index_merge_request_metrics_on_latest_closed_by_id"
     t.index ["merge_request_id", "merged_at"], name: "index_merge_request_metrics_on_merge_request_id_and_merged_at", where: "(merged_at IS NOT NULL)"
     t.index ["merge_request_id"], name: "index_merge_request_metrics"
-    t.index ["merged_at", "id"], name: "index_merge_request_metrics_on_merged_at_and_id"
+    t.index ["merged_at"], name: "index_merge_request_metrics_on_merged_at"
     t.index ["merged_by_id"], name: "index_merge_request_metrics_on_merged_by_id"
     t.index ["pipeline_id"], name: "index_merge_request_metrics_on_pipeline_id"
   end