On Thu, Sep 4, 2008 at 7:13 PM, Tom Lane <[EMAIL PROTECTED]> wrote: > "Alex Hunsaker" <[EMAIL PROTECTED]> writes: >> Ok let me know if this is to naive of an approach or not hitting the >> right cases you want tested. > > You have the unique-versus-not dimension, but I'm also wondering about > narrow vs wide index keys (say about 8 bytes vs 50-100 or so). In the > former case we're not saving any index space by storing only the hash > code, so these could be expected to have different performance > behaviors.
Arg yes... I just read the last part of your mail in this thread. I think it was the one on -hackers that talked about narrow vs wide... so I figured I would just try to do what the thread where you posted the patch talked about namley the below: >So my thinking right now is that we should just test this patch as-is. >If it doesn't show really horrid performance when there are lots of >hash key collisions, we should forget the store-both-things idea and >just go with this. So I thought, lets try to generate lots of hash collisions... obviosly though using the same key wont do that... Not sure what I was thinking > As for specifics of the suggested scripts: > > * might be better to do select count(*) not select 1, so that client > communication is minimized Yar. > * check that the queries actually use the indexes (not sure that the > proposed switch settings ensure this, not to mention you didn't create > the indexes) Well I was assuming I could just test the speed of a hash join... > * make sure the pgbench transaction counts are large enough to ensure > significant runtime > * the specific table sizes suggested are surely not large enough Ok -- Sent via pgsql-patches mailing list (pgsql-patches@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-patches
