understanding 'manual purge'

The purge routine reads the settings for visitor, bot, and rss purges, and then deletes entries from the hits table that are older than those settings specify. If there is nothing older to delete, nothing is deleted. Depending on your settings, it could take some time for the hits table to hold entries old enough to exceed the purge values.

After the hits table purge, there may be entries in the IP, User Agent, Referrer, and Req. URI tables that are no longer referenced from the hits table, and they, too, are deleted.

gotchya – thanks