All cache tables, by definition, can be cleared at any time without the site breaking down and crying. Generally you shouldn't need to do so yourself, as Drupal will clean up after itself when it needs to. You can, however, just truncate a cache table if you think there's stale data in it without breaking the site.
The exception is cache_views, which in D5 does not rebuild-on-demand but only on certain events, such as adding a module or clicking the "clear views cache" button on the Tools tab of the Views admin page. Don't clear that one manually unless you really know what you're doing. :-)
Other than that, the cache system is usually safe to just leave alone.
--Larry Garfield
On Wed, 27 Feb 2008 11:34:15 -0500, sander-martijn lists@severeddreams.com wrote:
There are a lot of cache related tables in the database. Is there a list somewhere of which ones can be emptied safely, or can they all? Here is a list of the tables I am seeing and the number of rows:
cache 3 cache_block 33 cache_content 403 cache_filter 56 cache_menu 2 cache_page 0 cache_views 11-- [ Drupal support list | http://lists.drupal.org/ ]