True, but no matter what your choice of optimization, you will have a snag. You will be doing more reads than writes, and you will be doing an in-table mathematic transformation (set LFT=LFT+1 or RGT=RGT+2 for all rows whose left exceeds the newly inserted one...) That's linear, but IMHO well worth it...
Check http://www.intelligententerprise.com/001020/celko1_1.jhtml, someone already wrote an import query from adjacency list (which is what everyone's used to -- row points to parent row) into this app. <Disclaimer message="this might not make sense">I've never done this, but I'm sure you can avoid re-balancing your tree if you assign LFT,RGT values in increments of 100 (remember good old' prodos BASIC from my early apple childhood). This way a single insert won't force a rebalance. (you'd insert parent.LFT+1, and have for your children, all numbers between parent.LFT+2 until your sibling's LFT, or your parent's RGT (if you are an only child)... It would complicate things, but slow down your update rate...</Disclaimer> -Dov -----Original Message----- From: Ian Buzer [mailto:[EMAIL PROTECTED] Sent: Thursday, December 23, 2004 8:51 AM To: CF-Talk Subject: Re: In One? >You could set your table up in a "modified preorder tree traversal", so >each node has a "LFT" and "RGT" numeric value. I've done this in >several instances and it works great. Hey, thanks Dov, that's lovely. As far as I understand it so far, it does have the snag that if you make a change near the top of the hierachy, a whole lot of data below has to be updated. Also, in this particular instance, I'm importing the category heirachy from another app on a daily basis which uses the other schema, so I'm probably looking at a long process to convert it from one schema to another during the import. Ian ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Special thanks to the CF Community Suite Gold Sponsor - CFHosting.net http://www.cfhosting.net Message: http://www.houseoffusion.com/lists.cfm/link=i:4:188646 Archives: http://www.houseoffusion.com/cf_lists/threads.cfm/4 Subscription: http://www.houseoffusion.com/lists.cfm/link=s:4 Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4 Donations & Support: http://www.houseoffusion.com/tiny.cfm/54
