On Sun, 2007-02-09 at 13:04 -0500, Kenneth Marshall wrote: > 2. Evaluate the performance of different hash index implementations > and/or changes to the current implementation. My current plan is > to keep the implementation as simple as possible and still provide > the desired performance. Several hash index suggestions deal with > changing the layout of the keys on a page to improve lookup > performance, including reducing the bucket size to a fraction of > a page or only storing the hash value on the page, instead of > the index value itself.
You might find this patch useful: http://archives.postgresql.org/pgsql-patches/2005-05/msg00164.php It implements the "just store the hash in the index" idea; it also sorts the entries in a bucket by the hash value, which allows binary search to be used to locate candidate matches. I was surprised that this didn't result in a performance improvement for the benchmarks that I ran, but I never got around to investigating further (either running more benchmarks or checking whether there was a bug in the implementation). Unfortunately, the patch doesn't apply cleanly to HEAD, but I can merge it up to HEAD if you'd like. -Neil ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings