tagged_with should have option to exclude tag counts and order_by

[dignoe]

We have to use Model.tagged_with() in a complicated sql query that is used within another sql query for the purposes of getting the MAX(table.updated_at) for a cache key. The current implementation adds complexity (and therefore processing time) to the query by always forcing

select{count(tags.id).as( tags_count)}.
select{"#{t}.*"}.
order("tags_count desc")

This also creates a MySQL error (duplicate column) when paired with .select("table_name.updated_at"). So that Model.select('table_name.updated_at').tagged_with(['my','tags']) fails.

I'm forking this project and will attempt a patch and pull request.

[thbar]

Seconded - I was fairly surprised to see that there was this cound, and now the alias query too.

Having a way to disable counting and alias tags at query time would be neat.

@dignoe I'm going to extract the query for just retrieving the tagged objects, but if you already did that, could you please share it? Thanks!