On Fri, Aug 7, 2009 at 7:34 PM, Scott Carey<scott@xxxxxxxxxxxxxxxxx> wrote: > Well, there is CPU overhead for reading postgres pages and tuples. On a > disk subsystem that gets 1GB/sec sequential reads, I can't get more than > about 700MB/sec of I/O and on a select count(*) query on very large tables > with large rows (600 bytes) and its closer to 300MB/sec if the rows are > smaller (75 bytes). In both cases it is CPU bound with little i/o wait and > disk utilization under 65% in iostat. > > I also get over 13GB/sec to RAM from a single thread (Nehalem processor). > > I don't see how on any recent hardware, random access to RAM is slower than > sequential from disk. RAM access, random or not, is measured in GB/sec... I don't think anybody's arguing that. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
