Aggregation Improvements

In Oracle11g, the following changes have been made to enhance aggregation:

Aggregation by partition. See AGGREGATE command for details
Clearing variables based on different aggmap objects. See the CLEAR command for details.
Checking to see if there are any changes in an aggmap since the last time a variable was aggregated using that aggmap. See the CHANGEDRELATIONS function for details.
Checking to see any value in a variable has changed (or the number of values that have changed) since the last time a variable was aggregated. See the CHANGEDVALUES function for details.
Checking to see if a variable or one or more of its partitions has values. See the ISEMPTY function for details.
Identifying the depth of a hierarchy. See the HIERDEPTH command for details.