Subject: Re: [PATCH] Incremental sort (was: PoC: Partial sort)
To: James Coleman <jtc331@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@lists.postgresql.org,
 Alexander Korotkov <a.korotkov@postgrespro.ru>
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From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Message-ID: <cab5f03f-42b4-ee56-d295-0d4903579986@2ndquadrant.com>
Date: Thu, 6 Sep 2018 22:34:33 +0200
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On 09/06/2018 08:04 PM, James Coleman wrote:
> I disagree because it's not ideal to basically have to append pk to
> every index in the system just to get the ability to tie-break when
> there's actually very low likelihood of ties anyway.
> 
> A similar use case is trying to batch through a result set, in which
> case you need a stable sort as well.
> 
> The benefit is retaining the generality of indexes (and saving space in
> them etc.) while still allowing using them for more specific sorts. Any
> time you paginate or batch this way you benefit from this, which in many
> applications applies to a very high percentage of indexes.
> 

I 100% with this.

I see incremental sort as a way to run queries with fewer indexes that
are less query-specific, while still benefiting from them. Which means
lower overhead when writing data, lower disk space usage, and so on.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services