Our application uses JSON throughout, and i've found the JSON functions in postgres to be invaluable!

I recently refactored several functions which kind of organically grew from several different functions each with it's own SQL query into one big query.

Not only did performance increase by a significant amount, the whole function is basically just "run this query and return the result" as the JSON functions in postgres allow me to leave the actual processing in the database and to not have to do the always annoying "loop over the 30,000 rows that were returned to build a JSON file" thing which is never fast.