Re: Unnecessary calculations in Execproject

From: Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>
To: Aleksander Alekseev <aleksander(at)tigerdata(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, 赵庭海(庭章) <zhaotinghai(dot)zth(at)alibaba-inc(dot)com>
Subject: Re: Unnecessary calculations in Execproject
Date: 2025-09-19 17:28:42
Message-ID: CAEze2Wh74ToCU+rO-ogCSE5PLcGYqwYXeh_LF6g034ca_Zpo5Q@mail.gmail.com
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On Fri, 19 Sept 2025 at 15:59, Aleksander Alekseev
<aleksander(at)tigerdata(dot)com> wrote:
>
> Hi Zhao,
>
> Thanks for sharing.
>
> > I hacked some of the code into my extension to skip these unnecessary operations,
> > and the performance will improve by 2%~5%. Then I think that if there is a way
> > to remove the nodes corresponding to these redundant operations in the targetlist
> > when initializing the execute node, this performance optimization will be applicable
> > widely. If this idea can be approved, I can try to write a patch for it.
>
> Sounds like a promising area of research / improvement. If it improves
> performance for certain queries and doesn't cause any performance
> degradation for others, I don't see why it wouldn't be approved.
> Unfortunately it's hard to tell more without any specific patch on
> hands.

FYI, this issue has been discussed a few times before over time, more
recently with [0] and [1].

Kind regards,

Matthias van de Meent
Databricks

[0] https://postgr.es/m/2ca5865b-4693-40e5-8f78-f3b45d5378fb%40iki.fi
[1] https://postgr.es/m/flat/CABSN6Vc0VXr%2B1w%2Bdn0iUJ--LgGUwM6XwBxcXN%2BvF15fMsYE9cg%40mail.gmail.com

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