TreeCache with INVALIDATION_SYNC mode and DB sync issue.

[balderman]

Hi
I am using TreeCach with INVALIDATION_SYNC mode.
I cache large object graphs so I just want just to notify all cluster nodes when an entry is modified and make rest of the nodes fetch a fresh copy from DB.
Lets say I have 2 nodes cluster with node#1 and node#2.
A cached object is modified on node#1, it sends notification to the other node and update the records on DB.Now the load balancer ask node#2 to do something with this object, so it tries to fetch from cache, see its not there and goes to DB to get a fresh copy.
My concern is: What if node#1 did not commit the update yet? node#2 will get an old copy...
How can I make sure that I will fetch a "fresh" copy from DB?
Using the pojo cache will bypass this problem but I am limited with memory so I am afraid I cant use it.

Thanks

Avishay

[manik]

Invalidation messages are only sent out at commit-time. If your DB update is a part of the transaction (e.g., using a cache loader) then the 2nd node will see the change in time.

[balderman]

Hi
I am not sure I understand:
What do you suggest is that I will use a cache loader and wrap the the invalidation message with a transaction.
And since I am using a cache loader the object will be serialized to the DB (lets assume I am using JDBC cache loader) after the transaction is committed the other node will fetch the "fresh" copy from the cache loader DB table.
Is that what you mean?
Thanks
Avishay

[manik]

Yes