Question

The following SQL generates all matching records between two tables that have identical schemas and then proceeds to iterate over the cursor that stores this result set. I do a row by row insert with a commit at the end of this function. My question is how can I get the maximum performance from this type of query? Code follows:

BEGIN  
DECLARE    
   CURSOR foo IS  
        SELECT * FROM tableOne to  
        WHERE EXISTS (SELECT * FROM tableTwo tt  
                       WHERE TO.FOO = TT.FOO  
                       AND TO.BAR = TT.BAR);  --THIS TAKES 5 MINUTES (66 MILLION ROWS)
     BEGIN  
           FOR nextFoo IN foo  
     LOOP  
            INSERT INTO tracker t  
               (id,foo,bar,baz)  
            VALUES(trackerSequence.nextval, nextFoo.foo,nextFoo.bar,nextFoo.baz);  
     END LOOP;   
     COMMIT;  
     END;  
END;

This query can take upwards of an hour and I am trying to reduce the time cost associated with it. I will be processing 140 million records in general so I am expecting to double the amount of time this process takes. All columns are indexed.

Version information:

10g 10.2

Answer 1

I have found the following will do 130 million inserts in about 49 minutes.

INSERT INTO tracker t  
    SELECT * FROM tableOne to  
        WHERE NOT EXISTS (SELECT * FROM tableTwo tt  
                       WHERE TO.FOO = TT.FOO  
                       AND TO.BAR = TT.BAR);