On Jan 18, 2011, at 8:24 AM, Merlin Moncure wrote: > a few weeks back I hacked an experimental patch that removed the hint > bit action completely. the results were very premature and/or > incorrect, but my initial findings suggested that hint bits might not > be worth the cost from performance standpoint. i'd like to see some > more investigation in this direction before going with a complex > application mechanism (although that would be beneficial vs the status > quo).
If you're not finding much benefit to hint bits, that's *very* interesting. Everything I outlined certainly looks like a pretty damn expensive code path; it's really surprising that hint bits don't help. I think it would be very valuable to profile the cost of the different code paths involved in the HeapTupleSatisfies* functions, even if the workload is just pgBench. > an ideal testing environment to compare would be a mature database > (full clog) with some verifiable performance tests and a mixed > olap/oltp workload. We're working on setting such a framework up. Unfortunately it will only be 8.3 to start, but we hope to be on 9.0 soon. -- Jim C. Nasby, Database Architect j...@nasby.net 512.569.9461 (cell) http://jim.nasby.net -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
