How to handle deadlocks ?

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 ? Received on Mon Jun 10 1996 - 00:00:00 CEST