Re: Parallel tuplesort (for parallel B-Tree index creation)

On 09/06/2016 10:42 PM, Peter Geoghegan wrote:
> On Tue, Sep 6, 2016 at 12:39 PM, Peter Geoghegan <pg@heroku.com> wrote:
>> On Tue, Sep 6, 2016 at 12:08 AM, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
>>>> I attach a patch that changes how we maintain the heap invariant
>>>> during tuplesort merging.
>>
>>> Nice!
>>
>> Thanks!
>
> BTW, the way that k-way merging is made more efficient by this
> approach makes the case for replacement selection even weaker than it
> was just before we almost killed it.

This also makes the replacement selection cheaper, no?

> I hate to say it, but I have to
> wonder if we shouldn't get rid of the new-to-9.6
> replacement_sort_tuples because of this, and completely kill
> replacement selection. I'm not going to go on about it, but that seems
> sensible to me.

Yeah, perhaps. But that's a different story.

- Heikki