Add index to last verification columns on repository states

db/schema.rb

@@ -2179,6 +2179,8 @@ ActiveRecord::Schema.define(version: 20181204135932) do
     t.datetime_with_timezone "last_wiki_verification_ran_at"
     t.index ["last_repository_verification_failure"], name: "idx_repository_states_on_repository_failure_partial", where: "(last_repository_verification_failure IS NOT NULL)", using: :btree
     t.index ["last_wiki_verification_failure"], name: "idx_repository_states_on_wiki_failure_partial", where: "(last_wiki_verification_failure IS NOT NULL)", using: :btree
+    t.index ["project_id", "last_repository_verification_ran_at"], name: "idx_repository_states_on_last_repository_verification_ran_at", where: "((repository_verification_checksum IS NOT NULL) AND (last_repository_verification_failure IS NULL))", using: :btree
+    t.index ["project_id", "last_wiki_verification_ran_at"], name: "idx_repository_states_on_last_wiki_verification_ran_at", where: "((wiki_verification_checksum IS NOT NULL) AND (last_wiki_verification_failure IS NULL))", using: :btree
     t.index ["project_id"], name: "idx_repository_states_outdated_checksums", where: "(((repository_verification_checksum IS NULL) AND (last_repository_verification_failure IS NULL)) OR ((wiki_verification_checksum IS NULL) AND (last_wiki_verification_failure IS NULL)))", using: :btree
     t.index ["project_id"], name: "index_project_repository_states_on_project_id", unique: true, using: :btree
   end

ee/db/migrate/20181121175359_add_index_to_last_verification_columns_on_project_repository_states.rb

+# frozen_string_literal: true
+
+class AddIndexToLastVerificationColumnsOnProjectRepositoryStates < ActiveRecord::Migration[4.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  REPOSITORY_INDEX_NAME = 'idx_repository_states_on_last_repository_verification_ran_at'
+  WIKI_INDEX_NAME = 'idx_repository_states_on_last_wiki_verification_ran_at'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index(:project_repository_states,
+      [:project_id, :last_repository_verification_ran_at],
+      name: REPOSITORY_INDEX_NAME,
+      where: 'repository_verification_checksum IS NOT NULL AND last_repository_verification_failure IS NULL')
+
+    add_concurrent_index(:project_repository_states,
+      [:project_id, :last_wiki_verification_ran_at],
+      name: WIKI_INDEX_NAME,
+      where: 'wiki_verification_checksum IS NOT NULL AND last_wiki_verification_failure IS NULL')
+  end
+
+  def down
+    remove_concurrent_index_by_name(:project_repository_states, REPOSITORY_INDEX_NAME)
+    remove_concurrent_index_by_name(:project_repository_states, WIKI_INDEX_NAME)
+  end
+end