Re: [Firebird-devel] Max transaction duration

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

On 2002.12.14 04:25:12 -0500 Roman Rokytskyy wrote:
> > No, just a timeout detector IMO.  My basic argument is that detecting
> > connection failure is fine and good, but you can't rely on clients
> being
> > well behaved enough to kill their connections when they forget about
> their
> > transactions, so we need timeouts or leases or something for
> transactions
> > as well.
> 
> I this case I tend to agree with others that it is a responsibility of
> transaction manager to kill such client. As far as I know, no database
> tries
> to solve this problem.

It is a standard part of the xa stuff, and you'd only encounter it using
the xa parts of a database.  For instance, in java it's available through
the XAResource interface.

Even though the xa spec is perhaps more "advice on how to confuse your
customers" than an explanation of how its supposed to work, I'd be very
surprised if most db vendors didn't implement something as fundamental to
reliability as this in their xa support.  I think most databases actually
go much further than I am proposing and heuristically decide to rollback or
commit prepared transactions that are not ended within a timeout.  These
transactions can theoretically be recovered when the tm comes back up: the
reason for the database to end them unilaterally is to avoid problems with
too many locks.  I think the mga provides enough flexibility that we can
wait for the tm to provide the actual disposition of these tx.

david jencks
> 
> Does Firebird send keep-alive messages even there is no requests from the
> client, only open connection? If yes, I think JayBird is not replying on
> them now...
> 
> Best regards,
> Roman Rokytskyy
> 
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