Prepare async indexes for ci table int8 swaps

Add a migration to prepare async index creation for all indexes on
ci_builds_metadata and the unique index on
ci_builds.id_convert_to_bigint.

Changelog: other

db/post_migrate/20210824174615_prepare_ci_builds_metadata_and_ci_build_async_indexes.rb

+# frozen_string_literal: true
+
+class PrepareCiBuildsMetadataAndCiBuildAsyncIndexes < ActiveRecord::Migration[6.1]
+  include Gitlab::Database::MigrationHelpers
+
+  def up
+    prepare_async_index :ci_builds_metadata, :id_convert_to_bigint, unique: true,
+      name: :index_ci_builds_metadata_on_id_convert_to_bigint
+
+    prepare_async_index :ci_builds_metadata, :build_id_convert_to_bigint, unique: true,
+      name: :index_ci_builds_metadata_on_build_id_convert_to_bigint
+
+    prepare_async_index :ci_builds_metadata, :build_id_convert_to_bigint, where: 'has_exposed_artifacts IS TRUE',
+      name: :index_ci_builds_metadata_on_build_id_int8_and_exposed_artifacts
+
+    prepare_async_index_from_sql(:ci_builds_metadata, :index_ci_builds_metadata_on_build_id_int8_where_interruptible, <<~SQL.squish)
+        CREATE INDEX CONCURRENTLY "index_ci_builds_metadata_on_build_id_int8_where_interruptible"
+        ON "ci_builds_metadata" ("build_id_convert_to_bigint") INCLUDE ("id_convert_to_bigint")
+        WHERE interruptible = true
+    SQL
+
+    prepare_async_index :ci_builds, :id_convert_to_bigint, unique: true,
+      name: :index_ci_builds_on_converted_id
+  end
+
+  def down
+    unprepare_async_index_by_name :ci_builds, :index_ci_builds_on_converted_id
+
+    unprepare_async_index_by_name :ci_builds_metadata, :index_ci_builds_metadata_on_build_id_int8_where_interruptible
+
+    unprepare_async_index_by_name :ci_builds_metadata, :index_ci_builds_metadata_on_build_id_int8_and_exposed_artifacts
+
+    unprepare_async_index_by_name :ci_builds_metadata, :index_ci_builds_metadata_on_build_id_convert_to_bigint
+
+    unprepare_async_index_by_name :ci_builds_metadata, :index_ci_builds_metadata_on_id_convert_to_bigint
+  end
+
+  private
+
+  def prepare_async_index_from_sql(table_name, index_name, definition)
+    return unless async_index_creation_available?
+
+    return if index_name_exists?(table_name, index_name)
+
+    async_index = Gitlab::Database::AsyncIndexes::PostgresAsyncIndex.safe_find_or_create_by!(name: index_name) do |rec|
+      rec.table_name = table_name
+      rec.definition = definition
+    end
+
+    Gitlab::AppLogger.info(
+      message: 'Prepared index for async creation',
+      table_name: async_index.table_name,
+      index_name: async_index.name)
+  end
+end

db/schema_migrations/20210824174615

+830cf08352b0d1f0c7f08ea67107466ea1d6a478c6f47d5e19f0ffa6c57f5641
\ No newline at end of file

lib/gitlab/database/async_indexes/migration_helpers.rb

@@ -68,8 +68,6 @@ module Gitlab
           async_index
         end
 
-        private
-
         def async_index_creation_available?
           ApplicationRecord.connection.table_exists?(:postgres_async_indexes) &&
             Feature.enabled?(:database_async_index_creation, type: :ops)