From: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
---|---|
To: | Peter Geoghegan <pg(at)heroku(dot)com> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Corey Huinker <corey(dot)huinker(at)gmail(dot)com> |
Subject: | Re: Parallel tuplesort (for parallel B-Tree index creation) |
Date: | 2016-09-07 05:28:03 |
Message-ID: | 7bce3c43-c7a3-9708-1f39-d0d54b2bac80@iki.fi |
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Lists: | pgsql-hackers |
On 09/06/2016 10:42 PM, Peter Geoghegan wrote:
> On Tue, Sep 6, 2016 at 12:39 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
>> On Tue, Sep 6, 2016 at 12:08 AM, Heikki Linnakangas <hlinnaka(at)iki(dot)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
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