Re: Parallel Seq Scan

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Wed, Jan 28, 2015 at 10:40 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I thought the proposal to chunk on the basis of "each worker processes
>> one 1GB-sized segment" should work all right. The kernel should see that
>> as sequential reads of different files, issued by different processes;
>> and if it can't figure out how to process that efficiently then it's a
>> very sad excuse for a kernel.

> I agree. But there's only value in doing something like that if we
> have evidence that it improves anything. Such evidence is presently a
> bit thin on the ground.

Well, of course none of this should get committed without convincing
evidence that it's a win. But I think that chunking on relation segment
boundaries is a plausible way of dodging the problem that we can't do
explicitly hardware-aware scheduling.

regards, tom lane