On Wed, Jan 16, 2013 at 11:56:21PM -0300, Claudio Freire wrote: > 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
We can round-robin temp tablespace usage if you list multiple entries. > 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. Yes, and detecting when to use these parallel features will be hard. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
