Horton

Re: [PATCH] Use optimized single-datum tuplesort in ExecSort

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Ranier Vilela <ranier.vf@gmail.com>
Cc: Ronan Dunklau <ronan.dunklau@aiven.io>, James Coleman <jtc331@gmail.com>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2021-07-15T01:21:51Z
Lists: pgsql-hackers 
On Thu, 15 Jul 2021 at 12:30, Ranier Vilela <ranier.vf@gmail.com> wrote:
>
> Em qua., 14 de jul. de 2021 às 21:21, David Rowley <dgrowleyml@gmail.com> escreveu:
>> But, in v8 there is no additional branch, so no branch to mispredict.
>> I don't really see how your explanation fits.
>
> In v8 the branch occurs at :
> + if (ExecGetResultType(outerPlanState(sortstate))->natts == 1)

You do know that branch is in a function that's only executed once
during executor initialization, right?

David

Commits

  1. Make nodeSort.c use Datum sorts for single column sorts