Real Time Data Aggregation

i would like get some inputs, best practices around populating Periodic aggregation and Accumulated Aggregation tables from Real Time Data Source (PowerExchange)

Does the aggregation need to occur in real time or is the source simply real time?

If the aggragation can happen later, then simply batch up the real time transactions and process them when needed. Otherwise, update the aggregate as transactions come in (and deal with queueing and load distribution issues as needed).