Robert Haas <robertmhaas@xxxxxxxxx> writes: > On Fri, Mar 13, 2009 at 10:06 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: >> I assume you meant effective_io_concurrency. We'd still need a special >> case because the default is currently hard-wired at 1, not 0, if >> configure thinks the function exists. > I think 1 should mean no prefetching, rather than 0. No, 1 means "prefetch a single block ahead". It doesn't involve I/O concurrency in the sense of multiple I/O requests being processed at once; what it does give you is CPU vs I/O concurrency. 0 shuts that down and returns the system to pre-8.4 behavior. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
