ALL_ROWS would indeed prefer hash join and S/M over NL.
On 2004.01.06 17:14, Jay Wade wrote:
> Thanks again for all your help.
> Does the ALL_ROWS hint force a preference in Join Types as well?
> If so would it try to force a HASH JOIN?
>
>
> >From: Mladen Gogala <mgogala_at_adelphia.net>
> >Reply-To: ORACLE-L_at_fatcity.com
> >To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> >Subject: Re: Re[2]: OCP Question (Perf Tuning)
> >Date: Tue, 06 Jan 2004 13:24:25 -0800
> >
> >Oracle doesn't but Jonathan Lewis does, in his "Tutorials". I found out
> >about that
> >from Scott Gosset in 8i internals class in NYC. Seems still to be true.
> >Gospel of Jonathan should suffice, however. I just discovered that my
> >10053 trace name errorstack forever, level 12 causes ORA-600 in 9.2. Let me
> >look
> >for a patch and I'll come back later. As for the question being nontrivial
> >and unfair,
> >I agree.
> >
> >
> >On 2004.01.06 14:29, Jonathan Gennick wrote:
> > > Tuesday, January 6, 2004, 1:59:26 PM, Mladen Gogala
> >(mgogala_at_adelphia.net) wrote:
> > > MG> Nope. The answer is b). In the FIRST_ROWS mode, optimizer prefers NL
> >to all other
> > > MG> methos despite the price.
> > >
> > > Does Oracle themselves *document* that what you say is the
> > > case? I believe you, but I'm not sure that Oracle documents
> > > what you just said, so short of looking at the code, I'm not
> > > sure how anyone could be expected to really *know* what the
> > > answer to the original question was, which makes me wonder
> > > if the question is really even a fair question to ask.
> > >
> > > Do we *know* that B is the case, or have we just always
> > > *observed* that it *happens to be* the case?
> > >
> > > Best regards,
> > >
> > > Jonathan Gennick --- Brighten the corner where you are
> > > http://Gennick.com * 906.387.1698 * mailto:jonathan@gennick.com
> > >
> > > Join the Oracle-article list and receive one
> > > article on Oracle technologies per month by
> > > email. To join, visit
> >http://four.pairlist.net/mailman/listinfo/oracle-article,
> > > or send email to Oracle-article-request_at_gennick.com and
> > > include the word "subscribe" in either the subject or body.
> > >
> > >
> > >
> > >
> > > MG> On 2004.01.06 13:44, Jay Wade wrote:
> > > >> Hello:
> > > >>
> > > >> I was looking through some OCP questions posted on the web and came
> >across
> > > >> the one below.
> > > >> I believe the answer is (D), because the join type would be dependent
> >on the
> > > >> number of rows within the table. Is this correct or does the
> >OPTIMIZER_MODE
> > > >> set to FIRST_ROWS alter this behavior?
> > > >>
> > > >>
> > > >> The cost-based optimizer can choose between a nested loops join and a
> >sort
> > > >> merge join operation. All tables are analyzed and the OPTIMIZER_MODE
> >is set
> > > >> to FIRST_ROWS. Which execution plan will be the result?
> > > >>
> > > >> a. The sort-merge join.
> > > >>
> > > >> b. The nested loops join.
> > > >>
> > > >> c. This depends on some sort parameter values.
> > > >>
> > > >> d. This depends on the number of rows in each table.
> > > >>
> > > >> _________________________________________________________________
> > > >> Check your PC for viruses with the FREE McAfee online computer scan.
> > > >> http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
> > > >>
> > > >> --
> > > >> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > > >> --
> > > >> Author: Jay Wade
> > > >> INET: fish_dba_at_hotmail.com
> > > >>
> > > >> Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > >> San Diego, California -- Mailing list and web hosting services
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> > > >>
> > >
> > > MG> --
> > > MG> Mladen Gogala
> > > MG> Oracle DBA
> > > MG> --
> > > MG> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > >
> > > --
> > > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > > --
> > > Author: Jonathan Gennick
> > > INET: jonathan_at_gennick.com
> > >
> > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > > San Diego, California -- Mailing list and web hosting services
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> > > also send the HELP command for other information (like subscribing).
> > >
> >
> >--
> >Mladen Gogala
> >Oracle DBA
> >--
> >Please see the official ORACLE-L FAQ: http://www.orafaq.net
> >--
> >Author: Mladen Gogala
> > INET: mgogala_at_adelphia.net
> >
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> >also send the HELP command for other information (like subscribing).
>
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Jay Wade
> INET: fish_dba_at_hotmail.com
>
> Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> San Diego, California -- Mailing list and web hosting services
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--
Mladen Gogala
Oracle DBA
--
Please see the official ORACLE-L FAQ: http://www.orafaq.net
--
Author: Mladen Gogala
INET: mgogala_at_adelphia.net
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Received on Tue Jan 06 2004 - 16:34:29 CST
