Aggregate Table: Aggregate tables store precalculated measures that have been aggregate over a set of dimensional attributes.
This is very useful technique for speeding up query response time in decision support systems. This eliminates the need of run time calculations and delivers faster results to users.
The calculations are done ahead of time and the results are stored in the tables.
The key point is that the aggregate table should have fewer rows than the non aggregate table and therefore processing should be quicker.
Aggregate Persistence Wizard
Go to: OBIEE Admin > tool> Utilities > Aggregate Persistence Wizard