@Pierre: i know.. but first i'd have to find such a query from real-life. And also, i'm convinced that this query would be faster with a seqscan if the data wenen't cached.
@Arjen: thanks, that helps. But that's only the OS cache. There's also the shared_buffers, which are a postgres specific thing. I've found DISCARD in the manual<http://www.postgresql.org/docs/8.3/interactive/sql-discard.html>, but that only influences a single session, not the shared buffers. I reckon restarting the cluster should help, would it wipe out the cache? (pg_ctlcluster 8.3 main restart) Or is there a more graceful way? Cheers, WBL On Thu, Aug 26, 2010 at 7:37 PM, Pierre C <li...@peufeu.com> wrote: > > The bitmap heap scan is 3% faster, >> > > 3% isn't really significant. Especially if the new setting makes one query > 100 times slower... Like a query which will, by bad luck, get turned into a > nested loop index scan for a lot of rows, on a huge table which isn't in > cache... > -- "Patriotism is the conviction that your country is superior to all others because you were born in it." -- George Bernard Shaw
