AGGREGATOR

AGGREGATOR

1. ACTIVE

2. COMPONENTS

   • CACHE
     • Data cache - stores row data; in memory
     • Index Cache - stores group values; in memory
     • Aggregate Cache - stores data

3. Aggregate Expression

   • aggregate functions & nested aggregate functions
   • conditional clause - will eval to TRUE or FALSE
   • non-aggregate functions
   • NULL - default is NULL

4. calculations on groups

5. conditional clauses to filter rows

6. Incremental Aggregation - set up in session

   • uses historical cache data to perform aggregation calculations incrementally

7. Group by Ports -

8. Sorted Input - to decrease use of aggregate cache; imrpoves session performance;