[EMAIL PROTECTED] wrote:
Hi guys, I am quite sure this is the right behavior of the cache, but I would like some clarifications.
1) I read the content of a table and store the corresponding objects in a Collection. 2) I update the content of the objects. 3) I re-read the content of the table without updating the modified object. 4) Instead of replacing the content of the updated object with the content stored in the database, the updated object is retrieved a such with its modifications.
My questions are:
1) Is this due to the internal cache ?
Exactly! If you perform any OJB query, OJB will first check if a result object is already cached. If so, the cached version is returned.
(even when the cached object is dirty (i.e. contains uncommitted changes))!
2) How can I ask OJB to retrieve only comitted changes from the database ?
1. you can call broker.clearCache() to empty the cache before performing a query.
2. you can also set the class-descriptor attribute refresh="true" this will advise OJB to always load instances of a given class from the db and not from the cache.
3. you can use the PerBrokerCache so that changes to cached objects are only visible within one thread.
3) If I use a muti-user environnment will each user get the same copy of the object (i.e. the updated one) even if I have still not store the object ?
By default OJB uses a global cache, so changes to any cached objects are visible across the whole JVM.
You should use the PerBrokerCache in a multi user / multi thread environment to change this behaviour. See OJB.properties for details.
4) Does this behavior have anything to do with the optimistic caching ?
You mean Optimistic Locking? Not really. It's just Global vs. Local cache.
cheers, Thomas
Thanks and regards,
Patrick Reyes
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