chskumar

 Profile Answers by chskumar 

• Dec 27th, 2007

 

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 amout 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 aggregrate 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 BusinessObjects prompts.