ER/Studio - Embarcadero Technologies Product Documentation

USING ER/STUDIO > COMMON TASKS
• Ragged: In a ragged dimension, the logical parent of at least one member is missing from the level immediately
above the member. Ragged dimensions allow for hierarchies of indeterminate depth, such as organizational
charts and parts explosions. For example, in an organization some employees can be part of a team which is
managed by a team leader, while other employees report directly to the department manager. Another example
of a ragged dimension is illustrated in the model below which shows that cities such as: Washington, D.C.;
Vatican City; and Monte Carlo do not belong to states.
• Shrunken: A shrunken table is a version of the fact table that it is attached to but with fewer attributes in order to
draw attention to those specific attributes.
• Slowly Changing Type 0, 1, 2, 3, 6: Slowly changing dimensions capture information such as the customer’s
income level or income-to-debt ratio which can change overtime. The most commonly used methods to maintain
these changes are:
• Type 0: No effort has been made to deal with the changes.
• Type 1: Overwrites the existing dimension member values. Does not track the change history.
• Type 2: Creates a new row with the current dimension member. Tag the original row as expired.
• Type 3: Used for dimensions that change with a predictable rhythm, such as every year. Every dimension row
has a current category attribute that can be overwritten as well as attributes for each annual designation, such
as 2008 category and 2009 category.
• Type 6: Combines the approaches of types 1, 2, and 3. For changes to this type of table, the row is overwritten
but the table can contain an additional pair of date columns to indicate the date range at which a particular row
in the dimension applies, or the table can contain a revision number.
EMBARCADERO TECHNOLOGIES > ER/STUDIO® 8.0.3 USER GUIDE 91