On 5/24/23 22:19, Andres Freund wrote:
>
> ...
>
> Hm - stepping back a bit, why are we doing the work in ExecGetAllUpdatedCols()
> over and over? Unless I am missing something, the result doesn't change
> across rows. And it doesn't look that cheap to compute, leaving aside the
> allocation that bms_union() does.
>
> It's visible in profiles, not as a top entry, but still.
>
> Perhaps the easiest to backpatch fix is to just avoid recomputing the value?
> But perhaps it'd be just as problmeatic, because callers might modify
> ExecGetAllUpdatedCols()'s return value in place...
>
Yes, I think that's a perfectly valid point - I was actually wondering
about that too, but I was focused on fixing this in backbranches so I
left this as a future optimization (assuming it can be cached).
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
