> On Sat, Jun 8, 2013 at 5:04 AM, Simon Riggs <simon@2ndquadrant.com> wrote: > >> On 7 June 2013 20:23, Tom Lane <tgl@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
