Oracle Coherence 3.5

Aggregators

Coherence filters are great when you need to retrieve a subset of objects from the cache based on a certain criteria, but there are cases when you want to process these objects as well in order to return a single result.

For example, you might want to retrieve the total amount of all orders for a particular customer. One possible solution is to retrieve all the orders for the customer using a filter and to iterate over them on the client in order to calculate the total. While this will work, you need to consider the implications:

1. You might end up moving a lot of data across the network in order to calculate a result that is only few bytes long
2. You will be calculating the result in a single-threaded fashion, which might introduce a performance ...