Efficient implementation of faceted search in relational databases

Question

I am trying to implement a Faceted search or tagging with multiple-tag filtering. In the faceted navigation, only not-empty categories are displayed and the number of items

Answer 1

Regarding the counts, why pull them via SQL? You'll have to iterate through the result set in your code anyway, so why not make your count there?

I'm currently using this approach in a faceted search app I'm developing and it's working fine. The only tricky part is to setup your code to not output the facet until it reaches a new facet. At that time, output the facet and the number of rows you found for it.

This approach assumes you're pulling back a list of all matching items, and thus, multiple rows with the same facet. When you order this result by facet it's easy to get the count in your code instead.