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From: Robert Haas <[email protected]>
To: Etsuro Fujita <[email protected]>
Cc: Pg Hackers <[email protected]>
Subject: Re: postgres_fdw: Provide better emulation of READ COMMITTED behavior
Date: Thu, 5 Dec 2024 12:37:02 -0500
Message-ID: <CA+TgmoaYs6DLXrZB8NWzUi3YPL9yvBhFOG4UMENMCJ+WY2pn5A@mail.gmail.com> (raw)
In-Reply-To: <CAPmGK14Nj7vuJELKuhyiwMMhat8SsyUY+88yAyTZLdqXG0xYuw@mail.gmail.com>
References: <CAPmGK14Nj7vuJELKuhyiwMMhat8SsyUY+88yAyTZLdqXG0xYuw@mail.gmail.com>

On Thu, Dec 5, 2024 at 4:41 AM Etsuro Fujita <[email protected]> wrote:
> Comments welcome!  Maybe I am missing something, though.

I have a hard time seeing how this would work if cursors are in use on
the main server. Say I do this:

DECLARE foo CURSOR FOR SELECT * FROM ft1 UNION ALL SELECT * FROM ft2;
...fetch some rows from cursor foo but few enough that we only scan ft1...
...do something that causes a snapshot refresh like issue another query...
...fetch more rows from cursor foo until we start scanning ft2...

-- 
Robert Haas
EDB: http://www.enterprisedb.com

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