On Fri, Oct 24, 2008 at 12:42 AM, Tom Lane <[EMAIL PROTECTED]> wrote: >> non-portable, requires more user-to-system CPU, ... need I go on? > > I'd be interested to know which of these proposals you claim *is* > portable. The single biggest reason to reject 'em all is that > they aren't.
Yes, that was bad wording on my part. What I mean to say was unpredictable. Different OSes and filesystems handle fadvise differently (or not at all), which makes any claim to performance gain configuration-dependent. My preferred method, using O_DIRECT and fetching directly into shared buffers, is not without its issues or challenges as well. However, by abstracting the multi-block read interface, we could use more optimal calls depending on the OS. Having done a bit of research and testing in this area (AIO and buffer management), I don't see any easy solution. fadvise will work on some systems and will likely give some gain on them, but won't work for everyone. The alternative is to abstract prefetching and allow platform-specific code, which we rarely do. While we could build an abstract prefetch interface and simply use fadvise for it now (rather than OS-specific code), I don't see an easy win in any case. -- Jonah H. Harris, Senior DBA myYearbook.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
