Hey guys, you are too fast ...
... or no, I'm too slow, that's it :-), while writing my last message
Hey guys, you are too fast ...
... or no, I'm too slow, that is :-), while writing my last
message, you almost completely discussed the topic, someone
already implemented part of it and I can't keep up with your
speed. Facinating!
> > |but, I really don't think you should expose transaction-isolation
levels
> > |within CMP or in the definition of entities. This really belongs in
the
> > |creation of the connection pool. CMP cannot really guarantee that a
> > |connection will not be shared between different entity types
> > |within the same
> > |transaction that use the same connection pool. Actually, I'm pretty
sure
> >
> > which is why I am asking if the jdbc drivers support reconfiguration of
the
> > isolation level on the fly or is it pretty much a "constructor" thingy.
>
>
> It's on the fly, but it (generally) has to be set at the beginning of
> the transaction only.
As I just reviwed the Informix docs I have to correct:
With SET ISOLATION (the Informix way) you can change isolation 'on
the fly' inbetween SQL statements even inside a TX. With SET
TRANSACTION (the ANSI way to set isolation and RO/RW access) the
level is set at the beginning of a TX and remains in effect until
the TX ends.
With the current impl of JBoss pool picking the connection by TX
from the pool, both ways should be safe to use. The ANSI way
seems to be more portable, but less flexible.
The Informix way, beeing more flexible, seems to be risky, as the
order of accessing the DB with CMP seems to be not the order the
bean developer has in mind (remember deferred updates discussed
on another thread). Thus the isolation level has to be set before
every SQL statement issued against the DB, when switching the
level from bean to bean or even from method to method.
regards
Georg
___ ___
| + | |__ Georg Rehfeld Woltmanstr. 12 20097 Hamburg
|_|_\ |___ [EMAIL PROTECTED] +49 (40) 23 53 27 10
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