Re: delete based on multipart key

In article <33421BB9.2197@gte.net>, Douglas Wilson <dgwilson@gte.net> wrote: >Rudy Fernandes wrote: >> >> delete from first_table >> where a || b in ( select a || b from second_table);> >This works, but it is not exactly efficient since it will >not take advantage of the index on first_table columns (a,b). > This is odd! But true. Funnily, if the following statement is run, the index does get used. select a || b from first_table where a || b in (select a || b from second_table); but select * from first_table where a || b in (select a || b from second_table); results in a SEQUENTIAL SCAN of first_table Isn't this an optimizer goof up? Why should a || b be treated differently from a, b? Isn't the index (a,b) stored as a || b? ----------------------- Rudy Fernandes GIC, Kuwait OL 7.20UC4, 4GL 6.04UC1 -----------------------