Re: disfavoring unparameterized nested loops

On Mon, Jun 21, 2021 at 4:52 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I'm willing to take some flak if there's not an easy proof that the outer
> scan is single-row, but I don't think we should just up and change it
> for cases where there is.

I think that's a reasonable request. I'm not sure that I believe it's
100% necessary, but it's certainly an improvement on a technical
level, and given that the proposed change could impact quite a lot of
plans, it's fair to want to see some effort being put into mitigating
the possible downsides. Now, I'm not sure when I might have time to
actually try to do the work, which kind of sucks, but that's how it
goes sometimes.

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