Re: Use generation context to speed up tuplesorts

On Fri, Jul 30, 2021 at 2:42 AM David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
> Master:
> Sort Method: quicksort Memory: 5541kB
> Patched:
> Sort Method: quicksort Memory: 3197kB

Whoa.

> work_mem = '4GB';
> Test master gen sort compare
> Test1 317.2 665.6 210%
> Test2 228.6 388.9 170%
> Test3 207.4 330.7 159%
> Test4 185.5 279.4 151%
> Test5 292.2 563.9 193%

Very impressive.

An early version of what eventually became DSA worked with
backend-local memory and I saw very substantial memory usage
improvements on large sorts, similar to what you show here. I am not
sure I saw the same CPU improvements, and in any case I abandoned the
idea of using that infrastructure to manage backend-local memory at
some point, since the whole thing had lots of problems that I didn't
know how to solve. What you've done here looks like a much more
promising approach.

--
Robert Haas
EDB: http://www.enterprisedb.com