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Home -> Community -> Mailing Lists -> Oracle-L -> RE: full usefullness of CURRENT OF ???
I believe (I could be totally wrong here) the reason for the CURRENT OF is
both for performance and consistency.
The second example has to run the update statement seperately. CURRENT OF can go directly to the row(s) affected. CURRENT OF still has to modify each block header in the table to lock which is a small performance hit. To prevent that you could update by rowid and avoid the header updates.
Also, the CURRENT OF locks the table so that no one can modify (or even read) it while the transaction is taking place. This guarantees nothing is changing between retrieving values from the cursor and updating the table based on those values.
-----Original Message-----
Sent: Friday, July 11, 2003 1:54 PM
To: Multiple recipients of list ORACLE-L
Could anyone give us an idea as to the full usefullness
of CURRENT OF? Here are my two separate examples:
/* 1 this one has a CURRENT OF */
DECLARE CURSOR EmpCursor IS
SELECT * FROM Emp
FOR UPDATE; BEGIN FOR EmpRec IN EmpCursor LOOP
UPDATE EMP SET SALARY = SALARY * 1.08 WHERE CURRENT OF EmpCursor
END LOOP; END; /* 2 same as above, except without the CURRENT OF */
DECLARE CURSOR EmpCursor IS
SELECT * FROM Emp
FOR UPDATE; BEGIN FOR EmpRec IN EmpCursor LOOP
UPDATE EMP SET SALARY = SALARY * 1.08 WHERE EMP_ID = EmpRec.Emp_ID;
END LOOP; END; /
Is one more efficient than the other? If I could have done
business without the CURRENT OF, then why did oracle made
it available?
thx
maa
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