Re: How to handle deadlocks ?

In article <DsszAL.7MC_at_world.std.com>, bgw_at_world.std.com (Bruce G Wilson) says:
>
>
>I've been on a couple of contracting jobs where the client uses
>Sybase (4.9 and System 10). At each place, there were occasions
>where they had problems with deadlock: two processes trying to
>allocate two resources in opposite order. It struck me that part
>of the reason why this is such a problem is that locks are taken
>(and escalated) implicitly in Sybase, so that it's difficult from
>a superficial read of the code to tell when a lock is being taken
>and where the conflict might be occurring. I guess I'm kind of
>surprised to find that locks can't be taken explicitly; with this,
>it would be made clear in the code where the locks are being taken
>and might make it easier to determine where the problem is.
>
>I'm wondering, what kinds of techniques are used in "standard"
>practice with Sybase to detect/prevent deadlocks ? Do IS
>organizations establish rules for accessing the database, like,
>"always do an update to table A before doing an update to table B" ?
>It strikes me that that's really the only way to control this
>sort of problem.
>
>I can't imagine that other databases (Oracle, Informix) don't also
>have this kind of problem. How are deadlocks handled in these ?
>

Ordering access to the objects in your database is the best way to REDUCE dealock, keep transactions as short as possible too. To understand why you have a deadlock you can activate two traceflags, they will generate a stack in your errorlog with all the details (store proc, pages..) about your deadlock. Your applications must presume a deadlock can occurs anywhere, thus code deadlock processing. Received on Mon Jun 10 1996 - 00:00:00 CEST