Improving scalability of the modified preorder tree traversal algorithm

Question

I\'ve been thinking about the modified preorder tree traversal algorithm for storing trees within a flat table (such as SQL).

One property I dislike about the standard a

Answer 1

I have heard of people doing this before, for the same reasons, yes.

Note that you do lose at a couple of small advantages of the algorithm by doing this

• normally, you can tell the number of descendants of a node by ((right - left + 1) div 2). This can occasionally be useful, if e.g. you'd displaying a count in a treeview which should include the number of children to be found further down in the tree
• Flowing from the above, it's easy to select out all leaf nodes -- WHERE (right = left + 1).

These are fairly minor advantages and may not be useful to you anyway, though for some usage patterns they're obviously handy.

That said, it does sound like materialized paths may be more useful to you, as suggested above.