Automattic / jetpack

					$columns  = Jetpack_Sync_Defaults::$default_post_checksum_columns;

				}

				break;

			case "post_meta":

				$object_count = $this->post_count( null, $start_id, $end_id );

				$object_table = $wpdb->postmeta;

				$id_field     = 'meta_id';

				$where_sql    = Jetpack_Sync_Settings::get_whitelisted_post_meta_sql();

				if ( empty( $columns ) ) {

					$columns  = Jetpack_Sync_Defaults::$default_post_meta_checksum_columns;

				}

				break;

			case "comments":

				$object_count = $this->comment_count( null, $start_id, $end_id );

				$object_table = $wpdb->comments;

					$columns  = Jetpack_Sync_Defaults::$default_comment_checksum_columns;

				}

				break;

			case "comment_meta":

				$object_count = $this->post_count( null, $start_id, $end_id );

				$object_table = $wpdb->commentmeta;

				$id_field     = 'meta_id';

				$where_sql    = Jetpack_Sync_Settings::get_whitelisted_comment_meta_sql();

				if ( empty( $columns ) ) {

					$columns  = Jetpack_Sync_Defaults::$default_post_meta_checksum_columns;

				}

				break;

			default:

				return false;

		}