[GENERAL] json_agg doesn't generate the smallest json possible?

Hi all,

I'm trying to use json_agg to generate some json array from the rows (which contain some json columns) I selected. But
itseems the returned json contains some extraneous whitespace characters. Any efficient way I can get rid of them? 

Also a quick question, if the final result is meant to be sent to a client, should I use json_agg or jsonb_agg?

Thanks.

Glen