On Sun, Apr 19, 2015 at 7:09 PM, Jeff Janes <jeff.ja...@gmail.com> wrote: > I did literally the simplest thing I could think of as a proof of concept > patch, to see if it would actually fix things. I just jumped back a certain > number of blocks occasionally and prefetched them forward, then resumed the > regular backward scan. IIRC, this patches introduces optional prefetch for the backward scan where file system prefetch may not work well. The result is promising!
> Also, what would be the best way to drill a hole through bufmgr.c into md.c > so that the prefetch could specify an entire range, rather than looping over > each individual block? > Different from mdread(), which requires a buffer in argument. Extending mdprefetch() looks natural and safe to me. This shall also layout a foundation for other scan style optimizations. > What would have to be done to detect people running on SSD and disable the > feature, if anything? > There are other call sites of prefetch - so this shall be a topic not just for this optimization. Regards, Qingqing -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
