[oracle-l] Re: PL/Sql Update Table runs 38 hrs (so far)

From: paul bennett <pbennett_at_good-sam.com>
Date: Mon, 26 Jan 2004 15:03:55 -0600
Message-Id: <s0152c6d.089@gwmail3.corp.good-sam.com>

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;
  v_insert NUMBER(9,0) := 0;

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

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• Original Message ----- From: "Igor Neyman" <ineyman_at_perceptron.com> To: <oracle-l_at_freelists.org> Sent: Monday, January 26, 2004 8:33 PM Subject: [oracle-l] Re: PL/Sql Update Table runs 38 hrs (so far)

Agreed.
What about modified code Wolfgang suggested?

Igor Neyman, OCP DBA
ineyman_at_perceptron.com Received on Mon Jan 26 2004 - 15:03:55 CST