> Yes, you could use CFtransaction for this type of isolation, > but this can also cause problems that you wouldn't see with > cflock. Cftransaction isoloation='serializabile' for example > will give you an exclusive lock to all tables within the > transaction (most restrictive level of isloation). Depending > on what you're doing, this can be desirable or problematic as > this can easily cause database deadlocks which are almost > always highly frustrating to the end user, and are usually > equally frustrating to debug. Cflock will not (directly) > cause database deadlocks, but can be problematic if you have > a large number of requests that are going to be using the > cflock'ed code as a lock will wait (until timeout) for the > locked resource to be released. > > So potential database lock error vs potential cflock timeout > error - the choice is yours. :)
Databases provide concurrency control for exactly this purpose. If I want to control concurrent access within the database, I want to use the functionality that the database provides. It's there for a reason. Recommending the synchronization of application code to solve database concurrency problems goes against best practices for database applications as well as common sense. If you can use a less restrictive isolation level, of course, you should. As for deadlocks, these don't just happen - they require a certain level of complexity within your transactional logic. You need to have conflicting transactions which access the same resources in different order. For example, transaction 1 locks table A and needs to then lock table B, while transaction 2 locks table B and needs to then lock table A. This isn't as common as you imply. In any case, most DBMSs simply kill one of the two transactions to resolve the deadlock, and I don't see how that's any worse than a lock timeout from the end user's perspective - they both result in "no workie". Dave Watts, CTO, Fig Leaf Software http://www.figleaf.com/ Fig Leaf Software provides the highest caliber vendor-authorized instruction at our training centers in Washington DC, Atlanta, Chicago, Baltimore, Northern Virginia, or on-site at your location. Visit http://training.figleaf.com/ for more information! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Get the answers you are looking for on the ColdFusion Labs Forum direct from active programmers and developers. http://www.adobe.com/cfusion/webforums/forum/categories.cfm?forumid-72&catid=648 Archive: http://www.houseoffusion.com/groups/CF-Talk/message.cfm/messageid:288241 Subscription: http://www.houseoffusion.com/groups/CF-Talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=11502.10531.4
