Remove redundant ci_builds (status) index

changelogs/unreleased/ci-builds-status-index.yml

+---
+title: Remove redundant ci_builds (status) index
+merge_request: 21070
+author:
+type: performance

db/migrate/20180807153545_remove_redundant_status_index_on_ci_builds.rb

+# frozen_string_literal: true
+
+class RemoveRedundantStatusIndexOnCiBuilds < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    remove_concurrent_index :ci_builds, :status
+  end
+
+  def down
+    add_concurrent_index :ci_builds, :status
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20180726172057) do
+ActiveRecord::Schema.define(version: 20180807153545) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -345,7 +345,6 @@ ActiveRecord::Schema.define(version: 20180726172057) do
   add_index "ci_builds", ["stage_id", "stage_idx"], name: "tmp_build_stage_position_index", where: "(stage_idx IS NOT NULL)", using: :btree
   add_index "ci_builds", ["stage_id"], name: "index_ci_builds_on_stage_id", using: :btree
   add_index "ci_builds", ["status", "type", "runner_id"], name: "index_ci_builds_on_status_and_type_and_runner_id", using: :btree
-  add_index "ci_builds", ["status"], name: "index_ci_builds_on_status", using: :btree
   add_index "ci_builds", ["token"], name: "index_ci_builds_on_token", unique: true, using: :btree
   add_index "ci_builds", ["updated_at"], name: "index_ci_builds_on_updated_at", using: :btree
   add_index "ci_builds", ["user_id"], name: "index_ci_builds_on_user_id", using: :btree