new hashing function
От | Neil Conway |
---|---|
Тема | new hashing function |
Дата | |
Msg-id | 1015135371.5258.10.camel@jiro обсуждение исходный текст |
Ответы |
Re: new hashing function
Re: new hashing function |
Список | pgsql-hackers |
Hi, I've implemented Bob Jenkin's hash function for PostgreSQL; more information on the hash function can be found at http://burtleburtle.net/bob/hash/doobs.html I'm posting this to -hackers because I'd like to get some feedback on whether this actually improves performance. I've tested 2 situations locally: (1) pgbench, btree indexes (to test typical performance) (2) pgbench, hash indexes I haven't looked at the implementation of hash joins; if they happen to use this hash function as well, that would be another informative situation to benchmark. In my local tests, the performance in (1) is basically the same, while the performance in (2) is increased by 4% to 8%. If you could let me know the results on your local setup, it should become clear whether this patch is a performance win overall. Note that to test case (2) properly, you'll need to drop and re-create your pgbench indexes after you apply the patch (so that when the new indexes are created, they use the new hash function). Also, it would be a good idea to use concurrency level 1; at higher concurrency levels, hash indexes have a tendancy to deadlock (yes, I'm currently trying to fix that too ;-) ). Cheers, Neil -- Neil Conway <neilconway@rogers.com> PGP Key ID: DB3C29FC
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