Re: Optimising compactify_tuples()

On Mon, Aug 17, 2020 at 4:01 AM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> While writing this email, I checked the archives and discovered that a
> couple of other people have complained about this hot spot before and
> proposed faster sorts already[2][3], and then there was a wide ranging
> discussion of various options which ultimately seemed to conclude that
> we should do what I'm now proposing ... and then it stalled.

I saw compactify_tuples() feature prominently in profiles when testing
the deduplication patch. We changed the relevant nbtdedup.c logic to
use a temp page rather than incrementally rewriting the authoritative
page in shared memory, which sidestepped the problem.

I definitely think that we should have something like this, though.
It's a relatively easy win. There are plenty of workloads that spend
lots of time on pruning.

--
Peter Geoghegan