A bigger error in option (d) is that it leaves open the ambiguity of whether the rows should, or should not, be part of the answer to the join.
Oracle's choice of join could be affected by adding 1000000 rows to the table that should be included in the join, but remain unchanged if you add 1000000 rows that should not be included in the join. Frankly it's an appallingly bad question, and I think your assumption about the wrong answer you are required to give is correct. 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 One-day tutorials: http://www.jlcomp.demon.co.uk/tutorial.html Three-day seminar: see http://www.jlcomp.demon.co.uk/seminar.html ____UK___November The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.html ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Tuesday, January 06, 2004 9:54 PM > Jonathan noted that > > > Nope. The answer is b). In the FIRST_ROWS mode, optimizer > > prefers NL > > > to > > all other > > > methos despite the price. > > > > > > > Unless the alternative is a full tablescan on the inner > > table - in which case merge or hash joins can be > > considered. > > For some reason hash joins were excluded from the question. I can't > speculate as to what, other than oversight or limiting the answers to 4, the > reason for this might be. > > > I suspect the answer *wanted* is b) the focus being that FIRST_ROWS favours > index scans and NL joins. ISTM that d) ought to be ruled out as it refers to > rows not blocks but as usual I am probably wrong. > > Niall > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Jonathan Lewis INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
