deviateltd/silverstripe-googlesitemapautoupdate

Creates a Google sitemap.xml and auto-updates it whenever a page published.

SilverStripe Google Sitemap Auto Update

This module simply passes the responsibility of physically generating a sitemap.xml file to the QueuedJobs Module which it does after each write., _(*1)

The advantage of handing off this procedure to a message queue rather than just doing it immediately, will likely be more apparent on busy, content-heavy sites, who's content authors may already experience time-lags when saving content in the CMS., _(*2)

If you need anything more complicated such as auto-alerting Google of changes to your sitemap, you might consider the standard Google SiteMaps Module., _(*3)