getting existing dictionaries



I want to use dictionary for counting pupose. I need a simple counter
and after looking in the counter package I thought that dictionaries
will serve my purpose better. basically what I need is 3 dimensional
array:
type-merchant-key

type can be 'cmd' or 'url' and merchant have unknown patterns.
..
I saw dictionaries are more 2 dimensional array so I thought of doing:

dict incr $type-$merchant key

and then some command that does

dict getDictionaries $type*

BUT

I saw no command that can give me the dictionaries that exists based
on a pattern:

well... where can I go from here?
is dictinaries the wrong solution? any other way?
.