Derived tables are tables that you define in the universe schema. You create objects on them as you do with any other table. A derived table is defined by an SQL query at the universe level that can be used as a logical table in Designer.
Derived tables have the following advantages:
· Reduced
amount of data returned to the document for analysis.
You can include complex calculations and functions in a derived table.
These operations are performed before the result set is returned to a
document, which saves time and reduces the need for complex analysis of
large amounts of data at the report level.
· Reduced
maintenance of database summary tables.
Derived tables can, in some cases, replace statistical tables that hold
results for complex calculations that are incorporated into the universe
using aggregate awareness. These aggregate tables are costly to maintain
and refresh frequently. Derived tables can return the same data and provide
real time data analysis.
Derived tables are similar to database views, with the advantage that the SQL for a derived table can include prompts.