Magnus,
So, if the tree depth for an article is 8, and I add
more articles to
search for which all have a depth of 8 or less, no additional database
queries are neccessary. The individual query will grow in size,
though.
Databases aren't about number of queries sent, with our workloads
(ergh, 20000 SQL queries per second on a cluster) query count does
not matter that much. What matters though, is number of rows looked
up by each query, and how hot that data is. Whenever we give users
possibility to hit our disks, we slow our systems down.
limiting several searches to "articles in
[[Category:Physics]] and its
subcategories" appears to be immensely useful, so it might be well
worth
the DB stress from a user standpoint. (Damn you, users! ;-)
For sake of user experience we are in constant fight for and against
features. ;)
*shrug*, just EXPLAIN your queries and take a look how hard it's
going to hit our databases. And try that on our biggest category trees.
Domas