In my version (new one) it's in "Chapter 8: Effective SQL", paragraph "Top-N Query Processing with ROWNUM". mvg/regards Jo Igor Neyman <ineyman@xxxxxxxxxxxxxx> Sent by: oracle-l-bounce@xxxxxxxxxxxxx 03/11/2004 22:32 Please respond to oracle-l To: oracle-l@xxxxxxxxxxxxx cc: Subject: RE: query for top 10 sql? It's in "Effective Oracle". Don't have book with me to reference the page. Igor Neyman, OCP DBA ineyman@xxxxxxxxxxxxxx -----Original Message----- From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Mladen Gogala Sent: Thursday, March 11, 2004 1:44 PM To: oracle-l@xxxxxxxxxxxxx Subject: Re: query for top 10 sql? On 03/11/2004 10:39:05 AM, Igor Neyman wrote: > Obviously in this case (second out of 3) it doesn't make any difference. > But, if asked for top 10 out of 1000: > - Without optimization: all 1000 would have been sorted; > - With optimization: find top 10 and stop, no need to sort the rest 990. > > Igor Neyman, OCP DBA > ineyman@xxxxxxxxxxxxxx > > Quite frankly, I still don't know which book are you referring to, "effective oracle" or "101" and, if "1-on-1", which edition? I'm asking because things don't look very logical to me, so I'd like to read them. I'd be thankful if you specified the book more closely. It doesn't look logical to me to sort only 10 out of 1000 if I want to find the 10 maximal ones. Namely, to find 10 largest, I need to sort them all. I can stop producing output after 10th row, but I must sort them all, or use some fancy sort algorithm, significantly slower then topological sort or quick sort (see Knuth for the description of those). Tom's explanation of those seemingly contradicting facts is probably wonderful and I'd like to read it. As I have all 3 of his books, I'd appreciate if you could reveal your source. ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------