On Wed, Jan 16, 2013 at 11:44 PM, Bruce Momjian <br...@momjian.us> wrote: > On Wed, Jan 16, 2013 at 05:04:05PM -0800, Jeff Janes wrote: >> On Tuesday, January 15, 2013, Stephen Frost wrote: >> >> * Gavin Flower (gavinflo...@archidevsys.co.nz) wrote: >> > How about being aware of multiple spindles - so if the requested >> > data covers multiple spindles, then data could be extracted in >> > parallel. This may, or may not, involve multiple I/O channels? >> >> Yes, this should dovetail with partitioning and tablespaces to pick up >> on exactly that. >> >> >> I'd rather not have the benefits of parallelism be tied to partitioning if we >> can help it. Hopefully implementing parallelism in core would result in >> something more transparent than that. > > We will need a way to know we are not saturating the I/O channel with > random I/O that could have been sequential if it was single-threaded. > Tablespaces give us that info; not sure what else does.
I do also think tablespaces are a safe bet. But it wouldn't help for parallelizing sorts or other operations with tempfiles (tempfiles reside on the same tablespace), or even over a single table (same tablespace again). And when the query is CPU-bound, it could be parallelized by simply making a multithreaded memory sort. Well, not so simply, but I do think it's an important building block. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers