From: Michael Paquier <michael@paquier.xyz>
To: Robert Haas <robertmhaas@gmail.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: pgsql: Prevent tuples to be marked as dead in subtransactions on standb
Date: Sun, 24 Dec 2023 11:30:21 +0900
Message-ID: <ZYeXvRzLAUMo0oVK@paquier.xyz> (raw)
In-Reply-To: <CA+TgmobQNViB1E+b4njpXxcYH-ZG7f_c_yOvAautU26neY8q1w@mail.gmail.com>
References: <E1rD5HX-009rzG-AO@gemulon.postgresql.org>
<CA+TgmobQNViB1E+b4njpXxcYH-ZG7f_c_yOvAautU26neY8q1w@mail.gmail.com>
On Tue, Dec 19, 2023 at 03:15:42PM -0500, Robert Haas wrote:
> I don't think this is a good commit message. It's totally unclear what
> it means, and when I opened up the diff to try to see what was
> changed, it looked nothing like what I expected.
(Not my intention to ignore you here, my head has been underwater for
some time.)
> I think a better message would have been something like
> "startedInRecovery flag must be propagated to subtransactions".
You are right, sorry about that. Something like "Propagate properly
startedInRecovery in subtransactions started during recovery" would
have been better than what I used.
> And I
> think there should have been some analysis in the commit message or
> the comments within the commit itself of whether it was intended that
> this be propagated to subtransactions or not. It's hard to understand
> why the flag would have been placed in the TransactionState if it
> applied globally to the transaction and all subtransactions, but maybe
> that's what happened.
Alvaro has mentioned something like that on the original thread where
we could use comments when a transaction state is pushed to a
subtransaction to track better the fields used and/or not used.
Documenting more all that at the top of TransactionStateData is
something we should do.
> Instead of discussing that issue, your commit message focuses in the
> user-visible consequences, but in a sort of baffling way. The
> statement that "Dead tuples are ignored and are not marked as dead
> during recovery," for example, is clearly false on its face. If
> recovery didn't mark dead tuples as dead, it would be completely
> broken.
Rather than "dead" tuples, I implied "killed" tuples in this sentence.
Killed tuples are ignored during recovery.
--
Michael
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To: pgsql-committers@postgresql.org
Cc: michael@paquier.xyz, robertmhaas@gmail.com, pgsql-hackers@postgresql.org
Subject: Re: pgsql: Prevent tuples to be marked as dead in subtransactions on standb
In-Reply-To: <ZYeXvRzLAUMo0oVK@paquier.xyz>
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