| From: | David Steele <david(at)pgmasters(dot)net> |
|---|---|
| To: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [PATCH] Incremental sort |
| Date: | 2017-03-28 14:27:14 |
| Message-ID: | 47ce55a6-dd08-d15b-e9cf-ecaebe25ee21@pgmasters.net |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Hi Alexander,
On 3/20/17 10:19 AM, Heikki Linnakangas wrote:
> On 03/20/2017 11:33 AM, Alexander Korotkov wrote:
>> Please, find rebased patch in the attachment.
>
> I had a quick look at this.
<...>
> According to 'perf', 85% of the CPU time is spent in ExecCopySlot(). To
> alleviate that, it might be worthwhile to add a special case for when
> the group contains exactly one group, and not put the tuple to the
> tuplesort in that case. Or if we cannot ensure that the Incremental Sort
> is actually faster, the cost model should probably be smarter, to avoid
> picking an incremental sort when it's not a win.
This thread has been idle for over a week. Please respond with a new
patch by 2017-03-30 00:00 AoE (UTC-12) or this submission will be marked
"Returned with Feedback".
--
-David
david(at)pgmasters(dot)net
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