public function convert_anonymous_topic_authors( $start = 1 ) {

		$has_update = false;

		if ( ! empty( $this->sync_table ) ) {
			$query = $this->wpdb->prepare( "SELECT sync_table1.value_id AS topic_id, sync_table1.meta_value AS topic_is_anonymous, sync_table2.meta_value AS topic_author
				FROM {$this->sync_table_name} AS sync_table1
				INNER JOIN {$this->sync_table_name} AS sync_table2
				ON ( sync_table1.value_id = sync_table2.value_id )
				WHERE sync_table1.meta_value = %s
				AND sync_table2.meta_key = %s
				LIMIT {$start}, {$this->max_rows}", 'true', '_bbp_old_topic_author_name_id' );
		} else {
			$query = $this->wpdb->prepare( "SELECT wp_postmeta1.post_id AS topic_id, wp_postmeta1.meta_value AS topic_is_anonymous, wp_postmeta2.meta_value AS topic_author
				FROM {$this->wpdb->postmeta} AS wp_postmeta1
				INNER JOIN {$this->wpdb->postmeta} AS wp_postmeta2
				ON ( wp_postmeta1.post_id = wp_postmeta2.post_id )
				WHERE wp_postmeta1.meta_value = %s
				AND wp_postmeta2.meta_key = %s
				LIMIT {$start}, {$this->max_rows}", 'true', '_bbp_old_topic_author_name_id' );
		}

		foreach ( $this->count_rows_by_results( $query ) as $row ) {
			$anonymous_topic_author_id = 0;
			$this->query( $this->wpdb->prepare( "UPDATE {$this->wpdb->posts} SET post_author = %d WHERE ID = %d LIMIT 1", $anonymous_topic_author_id, $row->topic_id ) );

			add_post_meta( $row->topic_id, '_bbp_anonymous_name', $row->topic_author );

			$has_update = true;
		}

		return ! $has_update;
	}