Certain rules and guidelines apply when you create an aggregate view.
Consider the following rules and guidelines when you create an aggregate view:
Use sorted input to decrease the use of aggregate caches. Sorted input reduces the amount of data cached during the session and improves session performance.
Limit the number of input/output columns to reduce the amount of data the aggregate view stores in the data cache.
Filter the data before aggregating it.
If you create a column in the aggregate view, verify that the datatype, precision, and scale match the PowerCenter datatype, precision, and scale shown in the
Column Definitions
area. By default, the scale is 0.
You can either include single level functions, for example,
SUM(QUANTITY)
, or nested functions, for example,
MAX(COUNT(ITEM))
, in the output columns of an aggregate view. However, you cannot include both single level and nested functions in an aggregate view.