Add DB index on users.state

Closes #17920

CHANGELOG

@@ -7,6 +7,7 @@ v 8.9.0 (unreleased)
   - Fix groups API to list only user's accessible projects
   - Redesign account and email confirmation emails
   - Use gitlab-shell v3.0.0
+  - Add DB index on users.state
   - Add rake task 'gitlab:db:configure' for conditionally seeding or migrating the database
   - Changed the Slack build message to use the singular duration if necessary (Aran Koning)
   - Fix issues filter when ordering by milestone

db/migrate/20160528043124_add_users_state_index.rb

+class AddUsersStateIndex < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  def change
+    add_concurrent_index :users, :state
+  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: 20160525205328) do
+ActiveRecord::Schema.define(version: 20160528043124) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -1000,6 +1000,7 @@
   add_index "users", ["name"], name: "index_users_on_name", using: :btree
   add_index "users", ["name"], name: "index_users_on_name_trigram", using: :gin, opclasses: {"name"=>"gin_trgm_ops"}
   add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true, using: :btree
+  add_index "users", ["state"], name: "index_users_on_state", using: :btree
   add_index "users", ["username"], name: "index_users_on_username", using: :btree
   add_index "users", ["username"], name: "index_users_on_username_trigram", using: :gin, opclasses: {"username"=>"gin_trgm_ops"}