Refresh issues

Question

I wish to know if there are any refresh issues in the following scenario.
Consider the same application running in 2 distinct VM, jvm1 and jvm2 in a
simple
configuration without L2 cache.
In jvm1 I have:
PersistenceManager pm = pmf.getPersistenceManager();
pm.currentTransaction().begin();
Object oid = xxx;
Object o = pm.getObjectById(oid)
System.err.println(o.xxxx);
pm.currentTransaction().commit();
pm.close():
Then in jvm2:
PersistenceManager pm = pmf.getPersistenceManager();
pm.currentTransaction().begin();
Object oid = xxx;
Object o = pm.getObjectById(oid)
o.setSomeAttribute(xxxx);
pm.currentTransaction().commit();
pm.close():
Now if I execute in jvm1 the first code fragment, do I see the modification
applied in
jvm2 ?
Thanks in advance,
Guido Anzuoni.
BTW, are you going to include oid (and hopefully, class) keyword in
projection in kodo3 ?

Answer 1

Guido,
Yes, you will see the modification in the next PM. The only "stale data"
issues you might see are when you get object ID X in JVM1, modify and
commit object ID X in JVM2, and then continue to reference it in JVM1
(without any closing or refreshing): you will continue to see the cached
version of object ID X.
When this situation is intolerable, you can use pessimistic
transactions: that will guarantee up-to-date views of the object, at the
cost of keeping database locks on the rows open.
In article <[email protected]>, Guido Anzuoni wrote:
No, no, just for confirmation. I have read some posts on this topic and I
have only shown my tipical usage.
Is this behaviour somehow dependent on optimistic settings ?
What if the DB schema is a preexisting one and there is no column for
optimistic locking check ?
Thanks again,
Guido.
"Stephen Kim" <[email protected]> ha scritto nel messaggio
news:[email protected]...
Yes. Are you not seeing this behavior?
As for oid and class keywords, I'm not sure if the feature has been
resolved one way or another yet.
Guido Anzuoni wrote:
I wish to know if there are any refresh issues in the following
scenario.
Consider the same application running in 2 distinct VM, jvm1 and jvm2 ina
simple
configuration without L2 cache.
In jvm1 I have:
PersistenceManager pm = pmf.getPersistenceManager();
pm.currentTransaction().begin();
Object oid = xxx;
Object o = pm.getObjectById(oid)
System.err.println(o.xxxx);
pm.currentTransaction().commit();
pm.close():
Then in jvm2:
PersistenceManager pm = pmf.getPersistenceManager();
pm.currentTransaction().begin();
Object oid = xxx;
Object o = pm.getObjectById(oid)
o.setSomeAttribute(xxxx);
pm.currentTransaction().commit();
pm.close():
Now if I execute in jvm1 the first code fragment, do I see themodification
applied in
jvm2 ?
Thanks in advance,
Guido Anzuoni.
BTW, are you going to include oid (and hopefully, class) keyword in
projection in kodo3 ?
Stephen Kim
[email protected]
SolarMetric, Inc.
http://www.solarmetric.com
Marc Prud'hommeaux [email protected]
SolarMetric Inc. http://www.solarmetric.com