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From: Andy Fan <[email protected]>
To: PostgreSQL Hackers <[email protected]>
Subject: Re: raise ERROR between EndPrepare and PostPrepare_Locks causes ROLLBACK 2pc PAINC
Date: Wed, 25 Mar 2026 08:39:07 +0800
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

Andy Fan <[email protected]> writes:

> Hi,
>
> With the following hack in PrepareTransaction:
>
> @@ -2697,6 +2697,8 @@ PrepareTransaction(void)
>  	 */
>  	EndPrepare(gxact);
>  
> +	elog(ERROR, "some error");
> +
>  	/*
>  	 * Now we clean up backend-internal state and release internal resources.
>  	 */
>
> Then we can do the following test:
> CREATE TABLE t(a int);
> begin;
> insert into t values(1);
> prepare transaction 'foo';
> ERROR: some error.  //  before the lock transfer
> rollback prepared 'foo';
> PANIC:  failed to re-find shared lock object // because lock is released
> when ERROR.

I found a similar but not exactly same case at 2014 [1] which 
might be helpful to recall a boarder understanding on this area. 

[1] https://www.postgresql.org/message-id/534AF601.1030007%40vmware.com

-- 
Best Regards
Andy Fan

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