Speedup the dml ??

Hello, there

   I have two tables a,b ( a with 600000 records, b 60000 records)    Both a and b have the same columns c1 c2 c3 c4 c5.    I want to update a's c5 by b's c5 for the same key value c1-c4.    So,I create two unique indexies on a(c1,c2,c3,c4) and b(c1,c2,c3,c4).    

    update a

         set c5 = ( select c5 
                         from b 
                       where a.c1=b.c1 
                           and a.c2=b.c2 
                           and a.c3=b.c3 
                           and a.c4=b.c4 );
    
    Are there any better statement ( like EXISTS,or any hint to speedup) ??    
    Any ideas ??     
     

Rgds,
Agi Chen            Received on Fri Apr 14 2000 - 00:00:00 CDT