On Tue, Oct 12, 2010 at 3:07 PM, Jon Nelson <jnelson+pgsql@xxxxxxxxxxx> wrote: > On Tue, Oct 12, 2010 at 7:27 AM, Mladen Gogala > <mladen.gogala@xxxxxxxxxxx> wrote: >> >> So, the results weren't cached the first time around. The explanation is the >> fact that Oracle, as of the version 10.2.0, reads the table in the private >> process memory, not in the shared buffers. ÂThis table alone is Â35GB in >> size, ÂOracle took 2 minutes 47 seconds to read it using the full table >> scan. If I do the same thing with PostgreSQL and a comparable table, >> Postgres is, in fact, faster: > > Well, I didn't quite mean that - having no familiarity with Oracle I > don't know what the alter system statement does, but I was talking > specifically about the linux buffer and page cache. The easiest way to > drop the linux caches in one fell swoop is: > > echo 3 > /proc/sys/vm/drop_caches AFAIK this won't affect Oracle when using direct IO (which bypasses the page cache). Luca -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
