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help / color / mirror / Atom feedFrom: Alexander Korotkov <[email protected]>
To: SATYANARAYANA NARLAPURAM <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Subject: Re: Bug: WAIT FOR LSN crashes with assertion failure inside PL/pgSQL DO blocks and procedures
Date: Thu, 9 Apr 2026 09:00:06 +0300
Message-ID: <CAPpHfdsZ6YrzX-5uenwvw1VXuG7mpBXSOT6JFTg6aCCC0SaNEg@mail.gmail.com> (raw)
In-Reply-To: <CAHg+QDcN-n3NUqgRtj=BQb9fFQmH8-DeEROCr=PDbw_BBRKOYA@mail.gmail.com>
References: <CAHg+QDcN-n3NUqgRtj=BQb9fFQmH8-DeEROCr=PDbw_BBRKOYA@mail.gmail.com>
Hi, Satya!
On Thu, Apr 9, 2026 at 5:03 AM SATYANARAYANA NARLAPURAM
<[email protected]> wrote:
> An assertion failure (server crash in assert-enabled builds) occurs when WAIT FOR LSN ... INTO is used inside PL/pgSQL DO blocks or within void procedures.
>
> Repro:
>
> -- Run this on a standby
>
> CREATE PROCEDURE test_wait()
> LANGUAGE plpgsql AS $$
> DECLARE
> result text;
> BEGIN
> WAIT FOR LSN '0/1234' INTO result;
> RAISE NOTICE '%', result;
> END;
> $$;
> CALL test_wait();
>
>
> The WAIT FOR itself succeeds, but the very next PL/pgSQL statement that requires a snapshot crashes the backend with:
>
> TRAP: failed Assert("portal->portalSnapshot == NULL"),
> File: "pquery.c", Line: 1776
>
> Attached patches for both the test case and a potential fix. Please review.
Thank you for reporting. But I doubt the fix is correct. Even that
this particular might work OK, I don't think it's safe to release
snapshots belonging to functions/procedures: it might affect them. I
tend to think we must forbid wrapping WAIT FOR LSN with
functions/procedures. I'll explore more on this today.
------
Regards,
Alexander Korotkov
Supabase
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To: [email protected]
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Subject: Re: Bug: WAIT FOR LSN crashes with assertion failure inside PL/pgSQL DO blocks and procedures
In-Reply-To: <CAPpHfdsZ6YrzX-5uenwvw1VXuG7mpBXSOT6JFTg6aCCC0SaNEg@mail.gmail.com>
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