On 28 January 2013 10:47, Heikki Linnakangas <hlinnakan...@vmware.com> wrote:
> There's also some overhead from empty > buckets when scanning the hash table Seems like we should measure that overhead. That way we can plot the cost against number per bucket, which sounds like it has a minima at 1.0, but that doesn't mean its symmetrical about that point. We can then see where the optimal setting should be. Having said that the hash bucket estimate is based on ndistinct, which we know is frequently under-estimated, so it would be useful to err on the low side. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
