Re: Organize working memory under per-PlanState context

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Andrei Lepikhov <lepihov(at)gmail(dot)com>, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Organize working memory under per-PlanState context
Date: 2025-08-20 17:00:49
Message-ID: d776d2de48e6f0e71b110913b24aab44326fee36.camel@j-davis.com
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On Wed, 2025-08-20 at 09:22 +0200, Andrei Lepikhov wrote:
> I'm not sure I understand your reasoning clearly. How do you know
> that
> the current subtree will not be rescanned with the same parameter
> set?
> Building a hash table repeatedly may be pretty costly, no?

We can check the eflags for EXEC_FLAG_REWIND. That might not be the
only condition we need to check, but we should know at plan time
whether a subtree might be executed more than once.

Regards,
Jeff Davis

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