The aggregations are done by Storm. persistentAggregate provides only a means to access the datastore to get the current aggregate for the specified key (using the IBackingMap's multiGet() implementation), provide that aggregate as the input to the Aggregator implementation along with other same-keyed tuples in the current batch (the groupBy/GroupedStream), and persist it back to the database using multiPut().
On Tuesday, May 27, 2014, Raphael Hsieh <[email protected]> wrote: > From my understanding, PersistentAggregate should first aggregate the > batch, then once the batch has finished aggregating, send it to whatever > datastore is specified. > > Is this the case ? Or will the Persistent Aggregate use the external > datastore in order to do the aggregations ? > > -- > Raphael Hsieh > > > -- Danijel Schiavuzzi E: [email protected] W: www.schiavuzzi.com T: +385989035562 Skype: danijels7
