Re: Re[2]: [Firebird-devel] Max transaction duration

[David J. <dav...@di...>]

On 2002.12.12 05:02:55 -0500 Pavel Cisar wrote:
> Hi,
> 
> On 11 Dec 2002 at 15:43, Daniel Rail wrote:
> 
> > I, too, like the idea of a maximum transaction duration.
> 
> No! Trying to solve the problem that majority doesn't have or can solve 
> in different way by shifting the whole system out of balance is really a 
> bad idea. Linus or Jim Starkey would send any such proposal promptly and 
> colourfully to the place it deserve - a tenth circle of hell.

Umm, then they should share their wisdom on reliable distributed system
design with the  rest of the world, which AFAIK universally uses timeouts
to model node failure in distributed systems.  This can be explicit as in
the XA transaction model with transaction timeouts (a fairly old example)
and JINI leases (a much newer example) or implicit as in systems with
heartbeats.


Typically transaction managers use "presumed abort" optimization so they
don't make any permanent record of a transaction until the prepare phase is
successful.  They don't make any cleanup attempts on transactions they
haven't prepared.  Therefore some kind of "forget on timeout" for
unprepared transactions in the database is needed for automatic recovery. 
I'm considerably less enthusiasitic about  heuristic completion of prepared
transactions on timeout.

david jencks



> 
> Better solution is to provide a method to monitor transactions (for 
> example through temporary system tables like in IB7), so anyone 
> interested can write a small monitor app. that will kill the long 
> transaction or far better page the sysadmin's beeper.
> 
> Best regards
> Pavel Cisar
> http://www.ibphoenix.com
> For all your upto date Firebird and
> InterBase information
> 
> 
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