ALTER DIMENSION [ schema. ] dimension
  { ADD { level_clause
        | hierarchy_clause
        | attribute_clause
        | extended_attribute_clause
        }
  } ...
  |
  { DROP { LEVEL level [ RESTRICT | CASCADE ]
         | HIERARCHY hierarchy
         | ATTRIBUTE attribute [ LEVEL level [ COLUMN column ] ]...
         }
  } ...
  |
  COMPILE
  ;