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