I am in the process of mapping the categorization which would include:

- Categories (having one or more subcategories)
- Subcategories (having one or more parent categories, and one or more tags as children)
- Tags (these are further segmentation of categorization, and would have one or more (usually more) parent subcategories).

Each of them would have the following attributes:
- Name
- Slug (for SEO purposes)
- EntryCount (entry = post, number of entries/posts that have assigned that cat/subcat/tag to it)
- ParentCount (for example, how many parent categories this subcat has)
- ChildCount (how many children...)
- Subcategories would have both ParentCount and ChildCount

I'm thinking about a base class, something like Taxonomy - which may hold the common attributes?

Anyway, does anyone think there should be inheritance involved?

You can map the Toxonomy base class as @MappedSuperclass so that the inheritance module is materialized in the DB since it might not be very useful for polymorphic queries.

I will certainly try to implement it that way and see how it goes. Thanks for your input.

At the moment, I've proceeded with @ManyToMany (but actually two @OneToMany, as you suggest in your book) mapping between:

- Entry/post and Category
- Category and Subcategory,
and finally (not yet there),
- Subcategory and Tag

Do you think such a solution would be acceptable or is it too much classes/tables for what I need to achieve?

Don't worry about a few extra classes if they enable you to get better performance and much more flexibility