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From: Pavel Stehule <[email protected]>
To: Haritabh Gupta <[email protected]>
Cc: [email protected]
Subject: Re: proposal: schema variables
Date: Wed, 4 Mar 2026 20:15:26 +0100
Message-ID: <CAFj8pRDBr516DeKjQ4kRg8XZeScsTBFLZMY3dpN8kpVM2TKv1A@mail.gmail.com> (raw)
In-Reply-To: <177261853144.1094601.11795093672679754617.pgcf@coridan.postgresql.org>
References: <CAFj8pRDY+m9OOxfO10R7J0PAkCCauM-TweaTrdsrsLGMb1VbEQ@mail.gmail.com>
	<CAFj8pRDLL-srue=m+je26vFrMzwETWwOfsEVNwr7=_KhuWA1bQ@mail.gmail.com>
	<177261853144.1094601.11795093672679754617.pgcf@coridan.postgresql.org>

Hi

st 4. 3. 2026 v 11:03 odesílatel Haritabh Gupta <[email protected]>
napsal:

> Hi,
>
> While reviewing I came across this behaviour and wanted to
> check whether it's intended:
>
>     CREATE TEMP VARIABLE y AS int;
>     LET y = 42;
>
>     BEGIN;
>     SAVEPOINT s1;
>     LET y = generate_series(1,2);  -- ERROR: too many rows
>     ROLLBACK TO s1;
>     SELECT VARIABLE(y);            -- returns 1, not 42
>
> It looks like svariableReceiveSlot writes the first row to the
> variable (pfree'ing the old datum) before the second row triggers the
> error, so the old value is lost even though LET failed.
>
> I understand variable values are intentionally non-transactional, but
> is it expected that a failed LET has this side effect?
>

Yes, it does like you describe it. It is the most simple solution, because
I don't need any extra buffer, and I can assign the value immediately when
I have the value.

I think I can postpone an assignment to svariableShutdownReceiver with a
few more lines to get the behaviour that you expect.

Regards

Pavel


> ---
> Haritabh Gupta
> Supabase


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