Re: Use generation context to speed up tuplesorts

On Sat, 7 Aug 2021 at 12:10, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
>
> On 8/6/21 3:07 PM, David Rowley wrote:
> > All of the tests show that the patches to improve the allocation
> > efficiency of generation.c don't help to improve the results of the
> > test cases. I wondered if it's maybe worth trying to see what happens
> > if instead of doubling the allocations each time, quadruple them
> > instead. I didn't try this.
> >
>
> I doubt quadrupling the allocations won't help very much, but I suspect
> the problem might be in the 0004 patch - at least that's what shows
> regression in my results. Could you try with just 0001-0003 applied?

But 0004 only changes the logic which controls the threshold of when
we allocate an oversized chunk. It looks like the threshold is 512KB
with the 0004 patch. My test is only doing a maximum allocation of
296 bytes so will never allocate an oversized chunk.

Can you explain why you think 0004 would cause performance regressions?

David