----- Original Message -----
From: "Rickard �berg" <[EMAIL PROTECTED]>
> Do you agree?
I think the confusion may stem from the "locking" that an appserver may do
versus the database's "locking" mechanism.
In the appserver, pessimistic refers to those ejb containers that choose to
serialize access to their entity beans. Optimistic indicates that the ejb
container creates a separate instance of the entity bean to service each
concurrent thread.
On the database side, locking only has meaning with the context of a
transaction. The database won't allow more than one transaction to modify
the same record in a table. There is nothing inherent in databases to cause
a transaction to rollback if a previous transaction modified data that the
current transaction will be writing. This is true no matter what isolation
level is imposed on the database.
I believe that most of the discussion in this thread refers to the
containers choice on whether to be pessimistic or optimistic, and not the
databases isolation levels.
jim
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