Aggregate awareness is a term that describes the ability of 
a universe to
make use of aggregate tables in a database. These are 
tables that contain
pre-calculated data. You can use a function called 
@Aggregate_Aware in the
Select statement for an object that directs a query to be 
run against aggregate
tables rather than a table containing non aggregated data.
Using aggregate tables speeds up the execution of queries, 
improving the
performance of SQL transactions.
The reliability and usefulness of aggregate awareness in a 
universe depends
on the accuracy of the aggregate tables. They must be 
refreshed at the same
time as all fact tables.
A universe that has one or more objects with alternative 
definitions based on
aggregate tables is said to be “aggregate aware”. These 
definitions
correspond to levels of aggregation. For example, an object 
called Profit can
be aggregated by month, by quarter, or by year. These 
objects are called
aggregate objects.
Queries built from a universe using aggregate objects 
return information
aggregated to the appropriate level at optimal speed.

It is an ability to dynamically rewrite sql to the level 
granularity is needed to answer business question.

Allows faster query speed.