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[eluser]jplanet[/eluser]
Thanks for the replies. I have seen the posts regarding the nested sets and adjacency lists. What I have is more similar to adjacency...a parent id column in categories for infinitely nestable categories, but products can belong to any number of categories, so I have a separate many-to-many table for ProductCategories:

- product_id
- category_id

So, I suppose the real question is whether there is any benefit SEO-wise to reduce the URL to contain only a product or category key, without specifying the function name...My guess is that it's likely not an issue, but perhaps more of a general SEO question rather than something specific to CodeIgniter...