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Home -> Community -> Mailing Lists -> Oracle-L -> [oracle-l] Re: PL/Sql Update Table runs 38 hrs (so far)
Good catch! I would have locked the wrong table.
Kevin
-----Original Message-----
From: paul bennett [mailto:pbennett_at_good-sam.com]
Sent: Monday, January 26, 2004 4:25 PM
To: oracle-l_at_freelists.org
Subject: [oracle-l] Re: PL/Sql Update Table runs 38 hrs (so far)
Hi Kevin:
I like the idea of using the cursor for a loop but I did not want to make
too many changes to the original code. As written however I do not think
your
code will work. For one thing we need to update pub17.pub_sysdate and not
pub14.mdate.
Paul Bennett
>>> ktoepke_at_rlcarriers.com 01/26/04 03:08PM >>>
Why not use a cursor for loop? Makes the code easy to read as well as
reduces errors (such as having the fetch in the wrong place!)
Kevin
DECLARE
CURSOR pub14_cur IS
SELECT pub14.mdate
FROM advdb.pub_14 pub14, advdb.pub pub_17
WHERE pub17.adno = pub14_rec.adno
AND pub17.pubno = pub14_rec.pubno
AND pub17.vno = pub14_rec.vno
AND pub17.pub_sysdate <> pub14_rec.mdate
FOR UPDATE OF mdate;
BEGIN
FOR pub14_rec IN pub14_cur LOOP
UPDATE advdb.pub pub17
SET pub17.pub_sysdate = pub14_rec.mdate
WHERE CURRENT OF pub14_cur;
v_insert := v_insert + 1;
IF MOD(v_insert,1000) = 0 THEN
COMMIT;
END IF;
END LOOP;
COMMIT;
DBMS_OUTPUT.PUT_LINE (v_insert||' records were inserted.');
END;
-----Original Message-----
From: paul bennett [mailto:pbennett_at_good-sam.com]
Sent: Monday, January 26, 2004 4:04 PM
To: oracle-l_at_freelists.org
Subject: [oracle-l] Re: PL/Sql Update Table runs 38 hrs (so far)
Here is some untested code that might address some of the issues:
DECLARE
CURSOR pub14_cur IS
SELECT pub17.ROWID row_id,
pub14.mdate
FROM advdb.pub_14 pub14, advdb.pub pub_17
WHERE pub17.adno = pub14_rec.adno
AND pub17.pubno = pub14_rec.pubno
AND pub17.vno = pub14_rec.vno
AND pub17.pub_sysdate <> pub14_rec.mdate;
pub14_rec pub14_cur%ROWTYPE;
BEGIN OPEN pub14_cur;
LOOP
FETCH pub14_cur INTO pub14_rec;
EXIT WHEN pub14_cur%NOTFOUND;
UPDATE advdb.pub pub17
SET pub17.pub_sysdate = pub14_rec.mdate
WHERE pub17.ROWID = pub14_rec.row_id;
v_insert := v_insert + 1;
IF MOD(v_insert,1000) = 0
THEN COMMIT;
END IF;
END LOOP;
COMMIT;
CLOSE pub14_cur;
DBMS_OUTPUT.PUT_LINE (v_insert||' records were
inserted.');
END; Paul Bennett
>>> jonathan_at_jlcomp.demon.co.uk 01/26/04 02:41PM >>>
That will work, given Wolfgang's assumption about uniqueness. But as it stands, Oracle will have to execute two subqueries for every row in the 18,000,000 row table (I'm not sure that any of the optimizer versions is currently smart enough to convert his query into a hash join with subquery update - but don't take my word for that, I haven't tested it).
The pl/sql loop will make a maximum of 500,000 probes into the 18,000,000 row table to update.
(I think we are also both assuming that all three of the join columns are not null, but the pl/sql may behave contrary to the OP's expectations if that were the case).
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
The educated person is not the person who can answer the questions, but the person who can question the answers -- T. Schick Jr
Next public appearances:
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One-day tutorials:
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Three-day seminar:
see http://www.jlcomp.demon.co.uk/seminar.html
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Agreed.
What about modified code Wolfgang suggested?
Igor Neyman, OCP DBA
ineyman_at_perceptron.com
Received on Mon Jan 26 2004 - 15:28:41 CST
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