On Tue, 2009-07-14 at 11:23 +0300, Heikki Linnakangas wrote: > > The single SQL example mentioned already has at least two mechanisms for > > improving performance of that type of query. We probably don't need > > another, or at least we need a good analysis of why. > > Well, another class of queries where index-only scans are beneficial is > when you fetch a range of rows from index, where the heap fetches result > in a lot of random I/O.
Which we just optimised, no? I see it could be even better, but do we really need that class of query to be optimized again? (Possibly...) I'm not doubting your ability to solve every problem we face, just advising that we crunch a few numbers before we spend months on implementing all of this. It would be useful to have projected gains and a useful test case ahead of time, so we can measure the potential as early as possible. Yes, you don't need to convince me before you proceed, but if you can at least share the thoughts that have convinced you that would help. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
