Thanks.
Would requiring a login for search keep resource usage at reasonable levels? (in future)
It helps, but members search far more than guests - especially when you consider all the clicks on the "New Posts" link.
(Were most searches by people or robots?)
Robots cannot (and should, hopefully, not) perform searches here.
Are searches by userid as expensive as searches for keywords?
No.
One might think searches by userid would merely need to follow a maintained list.
Hmm. Well, so would indexed keyword searches.
No "list" exists until one is created for you. You sound quite interested in search algorithms, and I would encourage you to delve deeper into how relational databases store and retrieve data.
Perhaps it's the construction of the view of the results that's expensive.
Assuming that we're on the same page here, "the construction of the view of the results" is the easy part. Creating all those results is the expensive part.
I sometimes wonder how much redundant work most search queries do. E.g. it might gather all sorts of data for many pages of results, whereas the user likely only looks at the first page.
Assuming that results are not cached, every search of the same type does the same amount of work. Viewing the second page of a search result is just like viewing the first - only the first page of items are skipped.
site:gtplanet.net at
Google is also an option (e.g. to use when local search is down). It has advantages and disadvantages (to the searcher) over local search. It may rely on search working to keep it up-to-date though.
You're essentially doing a site-specific Google search when you use the big search form at the top of all our forum pages. Only the "advanced search" runs a query on GTPlanet's server. Google constantly crawls and indexes the site, and you are searching their database (with their vastly more accurate and powerful algorithms) when you use that. The downside, obviously, is that you can't easily drill down your results to specific users or forums, and it's database may take a few days to catch up with the latest posts.
Oh. You do restrict searches to logged-in members only now, it seems. But the button is still on the pages even if you aren't logged-in. (No more "secret" password... 
) Does Google already have an account?
Once again, if you're using the big search box at the top of the forum pages, you're just querying Google's database. Although the page may contain GTPlanet's header, it's not actually generated by my server.
