On Sun, Sep 27, 2009 at 11:18 AM, Sam Mason <sam@xxxxxxxxxxxxx> wrote: > On Sun, Sep 27, 2009 at 06:05:51PM +0200, Gerhard Wiesinger wrote: >> A google research has shown that Gregory Stark already worked on that issue >> (see references below) but as far as I saw only on bitmap heap scans. > > Greg Stark's patches are about giving the IO subsystem enough > information about where the random accesses will be ending up next. > This is important, but almost completely independent from the case > where you know you're doing sequential IO, which is what you seem to be > talking about. FWIW I did work to write code to use FADV_SEQUENTIAL and FADV_RANDOM but couldn't demonstrate any performance improvement. Basically Postgres was already capable of saturating any raid controller I could test doing a normal sequential scan with 8k block sizes and no special read-ahead advice. -- greg -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
