Re: New 9.6 external sort guidance around temp_tablespaces and maintenance_work_mem

On Sat, Apr 30, 2016 at 4:26 PM, Bruce Momjian <bruce@momjian.us> wrote:
> On Sat, Apr 30, 2016 at 04:23:00PM -0700, Peter Geoghegan wrote:
>> Maybe there is a place to emphasize this change in the release notes.
>> I don't really want to make it about the external sort feature,
>> though, because enabling higher work_mem settings by making sure that
>> does not disadvantage external sorts is as much about enabling
>> HashAggregates as it is about enabling internal sorts.
>
> We do often mention in the release notes areas that will need retuning.

How do you feel about it in this instance?

As you may have gathered, my perspective is that the external sorting
patches were more about fixing a problem with tuplesort than about
improving its performance. The performance characteristics of the old
approach to sorting runs were all over the place, which made
increasing work_mem like taking one step forward, then two steps
backwards.

-- 
Peter Geoghegan