Forum OpenACS Improvement Proposals (TIPs): Re: TIP #71 (Proposed): Add Jon Griffin's new Paginator Procs to Core Release
Filling the cache is very slow if you have a large datastructure, for instance 5,600 threads in a forum like we do in the openacs Q&A forum. The query itself's not too bad, it's pulling the rows out of the rowset and stuffing them into an nsv cache variable that's taking most of the time.
The design philosphy behind the paginator seems to be "pay a fairly steep up-front cost so accessing every page afterwards costs roughly the same".
This isn't good. Normally people are going to reference more recent threads, blog entries, bugs sorted by some criteria, etc. LIMIT/OFFSET and Oracle ROWNUM tricks are faster for early entries in the rowset than those at the end, but that's OK given common usage patterns. Besides both Oracle and PG implement these constructs quite well, we don't really care if accessing the very first thread in the openacs Q&A forum takes a couple of tenths of a second longer than accessing the most recent one.
To put it bluntly the paginator's a bit evil and I'll just rewrite list builder to not use it, except perhaps the bits that generate that nice navigation bar.