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From Aristedes Maniatis <>
Subject Re: Caching query results
Date Mon, 25 Sep 2006 13:34:01 GMT

On 25/09/2006, at 10:41 PM, Francesco Fuzio wrote:

> <<It is important to understand that caching of *result lists* is  
> done independently from caching of *individual DataObjects and  
> DataRows*. Therefore the API is different as well. Also cached  
> results lists _are not synchronized across VMs (even the shared  
> cache)._>>_
> _So it seems that if my application is deployed in a cluster I have  
> to implement a custom _distributed_ invalidation mechanism.

It depends on how important it is that the data is up to date. One  
solution might be to add functionality to Cayenne which invalidates  
objects in the cache after a certain period of time (for instance 1  
hour). It is now possible to invalidate objects one at time (http://

We are examining the same problem in our application (not a web  
cluster, but a client/server application). For now we switched off  
caching, but we need to think through the issues. One solution is to  
implement a distributing messaging system to send notifications  
between clients - I think Andrus was looking at XMPP at one time  
( for this. Certainly it would be  
handy if a messaging system was built into Cayenne for this. It would  
also be useful for things like pessimistic locking.

Ari Maniatis

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