On Tue, Jun 11, 2013 at 9:45 AM, Tatsuo Ishii <is...@postgresql.org> wrote:
> > On Sat, Jun 8, 2013 at 5:04 AM, Simon Riggs <si...@2ndquadrant.com> > wrote: > > > >> On 7 June 2013 20:23, Tom Lane <t...@sss.pgh.pa.us> wrote: > >> > >> > As for other databases, I suspect that ones that have parallel > execution > >> > are probably doing it with a thread model not a process model. > >> > >> Separate processes are more common because it covers the general case > >> where query execution is spread across multiple nodes. Threads don't > >> work across nodes and parallel queries predate (working) threading > >> models. > >> > > Indeed. Parallelism based on processes would be more convenient for > > master-master > > type of applications. Even if no master-master feature is implemented > > directly in core, > > at least a parallelism infrastructure based on processes could be used > for > > this purpose. > > As long as "true" synchronous replication is not implemented in core, > I am not sure there's a value for parallel execution spreading across > multile nodes because of the delay of data update propagation. > True, but we cannot drop the possibility to have such features in the future either, so a process-based model is safer regarding the possible range of features and applications we could gain with. -- Michael
