update question

I have the following update query that need to join 3 tables. update table_a a
set (col2,col3)
= (select col2,col3 from table_b b

   where a.col1=b.col1
   and col4 in (select col1 from table_c    where col5=12345));

There are only 1k row when retreiving from (select col1 from table_c where col5=12345). However, this query takes forever. I run the explain plan and it looks like it is doing a full scan of table_a. Is it updating every row of table_a? Is there another way to do it?

Thanks in advance!

Ed

-----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own Received on Mon Apr 05 1999 - 17:27:25 CDT