Well a good tip for me was that the difference between two left values is not one but for example 10. In this case you can update your left & right values without having to update all the left & right values larger than a particular one when you insert a record or delete one. You can then reorganize your tree once a day and then you have your usual differences again. So check the following example:
Classical Nested Set: Node Left Right A 1 10 ? B 2 5 | ? C 3 4 ? D 6 9 ? E 7 8 If you now insert a new node F below the node B you have to update several nodes: Node Left Right A 1 12 ? B 2 7 | ? C 3 4 | ? F 5 6 ? D 8 11 ? E 9 10 In this particular case you had to update all nodes! The new more spaced nested set would look like: Node Left Right A 10 100 ? B 20 50 | ? C 30 40 ? D 60 90 ? E 70 80 An insert of the Node F below the node B would only require one insert: Node Left Right A 10 100 ? B 20 50 | ? C 30 40 | ? F 41 42 ? D 60 90 ? E 70 80 You see the rest of the nodes keep their values. Of course after several insert the tree might get crowdy, but with a little logic, you can manage this quite easily and get rid of tons of updates. Another good practice is to keep the left & right values in a separate table. Then only these values get updated and the main Table where the tree resides is untouched. I use a combination of nested set and parent child values. In this case I can reorganize the tree at any time. BTW: a very good book about nested set tree model is Joe Celko's "SQL for Smarties". He has released one about hierarchies in SQL as well. You might want to have a look at it. Greetings from Switzerland Gert Franz Railo Technologies GmbH [EMAIL PROTECTED] www.railo.ch Join our Mailing List german: http://de.groups.yahoo.com/group/railo/ english: http://groups.yahoo.com/group/railo_talk/ linked in: http://www.linkedin.com/e/gis/71368/0CF7D323BBC1 Mike Kear schrieb: > @Brad: thanks for the advice. Throws my plans into a spin, but not > as much as it might have it if the whole shebang gor fubared. (I > didnt know 'fubar' was a verb!). > > @Mark: It's MSSql 2005. Thanks for the tip Mark, I'll have a look at that. > > What is going to happen is event type {a} happens (lets say it's a > sale). That triggers a default action plan of umpteen things that > have to follow based on that event, documents that have to be filed, > people notified, approvals gained etc, then the the default plan has > to be modified to allow for the specifics of this particular > transaction. > > So the event has to trigger the generation of a whole heirarchy of > maybe up to 50 things that have to happen, some of which rely on > previous things being done > > Cheers > Mike Kear > Windsor, NSW, Australia > Adobe Certified Advanced ColdFusion Developer > AFP Webworks > http://afpwebworks.com > ColdFusion, PHP, ASP, ASP.NET hosting from AUD$15/mont > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;203748912;27390454;j Archive: http://www.houseoffusion.com/groups/CF-Talk/message.cfm/messageid:312749 Subscription: http://www.houseoffusion.com/groups/CF-Talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4
