Expiring the Database

Removing Resource Descriptions that are out of date is expiring the database. Resource Descriptions are removed only when you run the expiration. Expired Resource Descriptions are deleted, but the database size is not decreased.

One attribute of a Resource Description is its expiration date. Your robots can set the expiration date from HTML <meta> tags or from information provided by the resource’s server. By default, Resource Descriptions expire in three months from creation unless the resource specifies a different expiration date. Periodically your search server should purge expired Resource Descriptions from its database.