Re: Parallell Optimizer

> 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.