What is better and fast to use between decode and case

Question

Hi friends,
i wanted to know what is better to use decode or case in sql,which gives faster result.
thks
sonal....

Answer 1

Here's a very simple timing comparison. This table (actually it's a partition) has a little over 1 million rows.
As you can see, the timing difference is trivial. (I ran an earlier query to fetch the blocks from disk).
SQL> select sum(decode(balloon_flag
  2                   ,'Y',1
  3                   ,0
  4                   )
  5            ) bal_count
  6  from   prod.loan_master
  7  where  report_date = to_date('31-DEC-2005');
           BAL_COUNT
                9036
Elapsed: 00:00:07.65
SQL> select sum(case balloon_flag
  2                  when 'Y' then 1
  3                  else  0
  4             end
  5            ) bal_count
  6  from   prod.loan_master
  7  where  report_date = to_date('31-DEC-2005');
           BAL_COUNT
                9036
Elapsed: 00:00:07.68
SQL> select sum(case
  2                  when balloon_flag = 'Y' then 1
  3                  else  0
  4             end
  5            ) bal_count
  6  from   prod.loan_master
  7  where  report_date = to_date('31-DEC-2005');
           BAL_COUNT
                9036
Elapsed: 00:00:07.46