ALTER CLUSTER [ schema. ]cluster
  { physical_attributes_clause
  | SIZE integer [ K | M ]
  | allocate_extent_clause
  | deallocate_unused_clause
  | { CACHE | NOCACHE }
  }
    [ physical_attributes_clause
    | SIZE integer [ K | M ]
    | allocate_extent_clause
    | deallocate_unused_clause
    | { CACHE | NOCACHE }
    ]...
  [ parallel_clause ] ;