Hello Troels, On Sun, 2 Dec 2007, troels knak-nielsen wrote:
> We're about to implement an application, which will use a tree > structure as the main taxonomy. Instead of implementing the algorithm > ourself, we are considering using the tree from ezc. We are keen on > using a modified preorder (nested set), but looking through the table > at http://ezcomponents.org/docs/tutorials/Tree I had a few questions. > When the phrase "Simple operation" is used, I suppose that it means > that it's "cheap" to execute -- Not that the implementation is simple? Yes, it's often a simple query, which uses an index of some sorts. As the queries are simple, so is the implementation of course. > Also, does "simple" mean that it's a constant cost or what happens, > when the size of the tree scales? I'm sure, an in-depth answer gets > rather complex, but some indication of how each operation scales, > would be most informative. That's basically what the table tries to say without reverting to O notations. The value "Simple Operation" tells you that the backend only has to do one (or two or three) queries to get the result - and that the number of queries is always constant. > For example, I'm not entirely sure, what the implications of using > LIKE on large datasets is? I suppose, that in theory, LIKE should be > able to perform reasonably well, since the match is anchored, but I'm > not sure how well MySql (We use MySql) works. I'm not a real MySQL guru either, but I could run some benchmarks on this next week I suppose. If you have a more specific question about the cost of an operation, I'd be happy to explain you the algorithm. regards, -- Derick Rethans eZ components Product Manager eZ systems | http://ez.no -- Components mailing list [email protected] http://lists.ez.no/mailman/listinfo/components
