Ask about METHOD_OPT in 9i

Hi all,

   I have some confuse about METHOD_OPT. If my db just have some table configured monitoring. And I use script 1:

begin
  dbms_stats.gather_schema_stats(
      ownname          => 'USER_A',
      estimate_percent => dbms_stats.auto_sample_size,
      method_opt       => 'for all columns size auto',             
      cascade          => true
   );
end;

   If have a highly skewed data distribution, I can use option METHOD_OPT to create histogram for these columns (And seem as this option just effect to only tables that configured monitoring). Normally, if I had not yet determine which columns, I can use script 2:

begin
  dbms_stats.gather_schema_stats(
      ownname          => 'USER_A',