Re: [PoC] Asynchronous execution again (which is not parallel)

On Tue, Dec 8, 2015 at 9:10 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Mon, Nov 30, 2015 at 7:47 AM, Kyotaro HORIGUCHI
> <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>
> But is it important enough to be worthwhile? Maybe, maybe not. I
> think we should be working toward a world where the Gather is at the
> top of the plan tree as often as possible, in which case
> asynchronously kicking off a Gather node won't be that exciting any
> more - see notes on the "parallelism + sorting" thread where I talk
> about primitives that would allow massively parallel merge joins,
> rather than 2 or 3 way parallel. From my point of view, the case
> where we really need some kind of asynchronous execution solution is a
> ForeignScan, and in particular a ForeignScan which is the child of an
> Append. In that case it's obviously really useful to be able to kick
> off all the foreign scans and then return a tuple from whichever one
> coughs it up first.
>

How will this be better than doing the same thing in a way we have done
Parallel Sequential Scan at ExecutorRun() time?

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com