On Tue, May 3, 2016 at 10:58 AM, Robert Haas <robertmh...@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 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

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