Here's something: http://www.scenic-route.com/program/db/lists3.htm
-- Arj� > -----Original Message----- > From: Eirikur Hrafnsson [mailto:[EMAIL PROTECTED] > Sent: woensdag 8 december 2004 16:23 > To: Slide Developers Mailing List > Subject: Re: Optimizing SQL tree > > > Do you have any website references to that? > > > On 8.12.2004, at 13:58, Richard Emberson wrote: > > > Forget Mr. Celko's work on nested sets - its old stuff. Look for > > Vadim Tropashko's work on Farey Sequences and Continued Fractions - > > a much improved way of creating trees with generic SQL. > > > > Richard > > > > > > Max Pfingsthorn wrote: > >> Dear Developers, > >> I was recently looking up different algorithms to store > trees in an > >> SQL database. I have found these very interesting articles > from 1996. > >> The author, Joe Celko, writes that trees can be > represented as Nested > >> Sets (see the first article for some explanation). I think, this > >> might be useful to Slide's SQL backend and the querying of > the WebDAV > >> tree. 'Recursive' searches, i.e. depth=infinity, reduce to mere > >> SELECTs comparing integers rather than making the DB match > strings. > >> And, with a little extra, depth=1 is also a simple SELECT. > However, > >> inserts are a bit more expensive, which would be fine, > however, since > >> in general, the WebDAV repository is not written to so often in > >> comparison to the reads. > >> What do you think about restructuring the SQL to take advantage of > >> this? > >> For complete reference on the Nested Sets, see: > >> http://www.dbmsmag.com/9603d06.html > >> http://www.dbmsmag.com/9604d06.html > >> http://www.dbmsmag.com/9605d06.html > >> http://www.dbmsmag.com/9606d06.html > >> In general, I am very interested in optimizing the SQL > backend a bit > >> more. I noticed that the LIMIT clause is actually emulated > within the > >> backend instead of using the SQL feature. We are using > MySQL behind > >> Slide, so that would help us a lot. What do you think about > >> specializing the backend(s) even more to take full > advantage of the > >> different vendor-specific implementations? Of course, maintenance > >> would be harder, but it sure would give performance a kick. > >> Best regards, > >> Max Pfingsthorn > >> Hippo > >> Oosteinde 11 > >> 1017WT > >> Amsterdam > >> The Netherlands > >> > --------------------------------------------------------------------- > >> To unsubscribe, e-mail: [EMAIL PROTECTED] > >> For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > -- > > This email message is for the sole use of the intended > recipient(s) and > > may contain confidential information. Any unauthorized review, use, > > disclosure or distribution is prohibited. If you are not > the intended > > recipient, please contact the sender by reply email and destroy all > > copies of the original message. > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > > Best Regards > > Eirikur S. Hrafnsson, [EMAIL PROTECTED] > Chief Software Engineer > Idega Software > http://www.idega.com > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
