ALTER DIMENSION

Purpose

Use the ALTER DIMENSION statement to change the hierarchical relationships or dimension attributes of a dimension.

See Also: CREATE DIMENSION for more information on dimensions

Prerequisites

The dimension must be in your schema or you must have the ALTER ANY DIMENSION system privilege to use this statement.

A dimension is always altered under the rights of the owner.

Syntax

level_clause::=

hierarchy_clause::=

join_clause::=

attribute_clause::=

Keywords and Parameters

The following keywords and parameters have meaning unique to ALTER DIMENSION. The remaining keywords and parameters have the same functionality that they have in the CREATE DIMENSION statement.

See Also: CREATE DIMENSION

schema

Specify the schema of the dimension you want to modify. If you do not specify schema, Oracle assumes the dimension is in your own schema.

dimension

Specify the name of the dimension. This dimension must already exist.

ADD

The ADD clauses let you add a level, hierarchy, or attribute to the dimension. Adding one of these elements does not invalidate any existing materialized view.

Oracle processes ADD LEVEL clauses prior to any other ADD clauses.

DROP

The DROP clauses let you drop a level, hierarchy, or attribute from the dimension. Any level, hierarchy, or attribute you specify must already exist.

Restriction: If any attributes or hierarchies reference a level, you cannot drop the level until you either drop all the referencing attributes and hierarchies or specify CASCADE.

CASCADE	Specify CASCADE if you want Oracle to drop any attributes or hierarchies that reference the level, along with the level itself.
RESTRICT	Specify RESTRICT if you want to prevent Oracle from dropping a level that is referenced by any attributes or hierarchies. This is the default.

COMPILE

Specify COMPILE to explicitly recompile an invalidated dimension. Oracle automatically compiles a dimension when you issue an ADD clause or DROP clause. However, if you alter an object referenced by the dimension (for example, if you drop and then re-create a table referenced in the dimension), the dimension will be invalidated, and you must recompile it explicitly.

Example

Modifying a Dimension Example

This example modifies the time dimension:

ALTER DIMENSION time 
   DROP HIERARCHY week_month;
ALTER DIMENSION time
   DROP ATTRIBUTE cur_date;
ALTER DIMENSION time
   ADD LEVEL day IS time_tab.t_day
   ADD ATTRIBUTE day DETERMINES t_holiday;