Re: what to revert

On Tue, May 3, 2016 at 10:58 AM, Robert Haas <robertmhaas@gmail.com> wrote:

> - Snapshot Too Old.  Tom, Andres, and Bruce want this reverted.
> It regresses performance significantly when turned on.

When turned on, it improves performance in some cases and regresses
performance in others.  Don't forget it is currently back-patched
to 9.4 and in use for production by users who could not use
PostgreSQL without the feature.  PostgreSQL failed their
performance tests miserably without the feature, and passes with
it.

> It originally regressed performance significantly even when
> turned off,

Which was wildly exaggerated since most of the benchmarks
purporting to show that actually had it turned on.  I don't think
the FUD from that has really evaporated.

> but that might be fixed now.

Certainly all evidence suggests that, FUD to the contrary.

> Also, it seems to be broken for hash indexes, per Amit Kapila's
> report.

Yeah, with a fairly simple fix suggested immediately by Amit.  I'm
looking into a couple other angles for possible fixes, but
certainly what he suggested could be done before beta1.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company