You don't specify any performance requirements, so take a look at this: http://en.wikipedia.org/wiki/Nested_set_model http://en.wikipedia.org/wiki/Nested_set_m

You don't specify any performance requirements, so take a look at this: http://en.wikipedia.org/wiki/Nested_set_model http://en.wikipedia.org/wiki/Nested_set_model You will be able to update, but it will not be efficient. Also - questions of this type are more appropriate for StackOverflow than HackerNews.