Re: [HACKERS] [PATCH] Incremental sort

On 03/16/2018 09:47 AM, Alexander Korotkov wrote:
> On Fri, Mar 16, 2018 at 5:12 AM, Tomas Vondra
> <tomas.vondra@2ndquadrant.com <mailto:tomas.vondra@2ndquadrant.com>> wrote:
> 
>     I agree those don't seem like an issue in the Incremental Sort patch,
>     but like a more generic costing problems.
> 
> 
> Yes, I think so too.

I wonder if we could make the costing a bit more pessimistic, to make
these loses less likely, while still keeping the main wins (particularly
for the LIMIT queries). But that seems a bit like a lost case, I guess.

> Do you think we can mark this patch RFC assuming that it have
> already got pretty much of review previously.
> 

Actually, I was going to propose to switch it to RFC, so I've just done
that. I think the patch is clearly ready for a committer to take a
closer look. I really like this improvement.

I'm going to rerun the tests, but that's mostly because I'm interested
if the change from i++ to i-- in cmpSortPresortedCols makes a measurable
difference. I don't expect to find any issues, so why wait with the RFC?

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services