Horton

Re: 2PC-induced lockup

Hans-Jürgen Schönig <postgres@cybertec.at>

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From: Hans-Juergen Schoenig <postgres@cybertec.at>
To: Peter Eisentraut <peter_e@gmx.net>
Cc: pgsql-hackers@postgresql.org
Date: 2007-07-10T13:21:07Z
Lists: pgsql-hackers 
is it good to allow locks on system tables at all?
i am not so sure. have seen some disaster in the past with that. just  
consider somebody placing ACCESS EXCLUSIVE LOCK on a system table. it  
is basically denial of service.

	best regards,

		hans



On Jul 10, 2007, at 3:14 PM, Peter Eisentraut wrote:

> The following command sequence appears to lock up the database system:
>
> BEGIN;
> LOCK pg_authid;
> PREPARE TRANSACTION 'foo';
> \q
>
> After that you can't connect anymore, even in single-user mode.   
> The only way
> I could find is to clear out the pg_twophase directory, but I'm not  
> sure
> whether it is safe to do that.
>
> Should this be prevented somehow, and is there a better recovery path?
>
> -- 
> Peter Eisentraut
> http://developer.postgresql.org/~petere/
>
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