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 } ;