_renderUrl() problems

[itdpong]

problem 1:
when I use _renderUrl() to generate url (http://server.com/store?sortBy=+groupid) and pass to server side.
in server side, the sortBy value in php is ' groupid', + character was ignored since the url hasen't encoded.

problem 2:
I create a one page application, user may filter the records by a form when they submit the form.
the result is the url become longer and longer when user submit the form more than 1 time. for example:

the url is like this: http://server.com/store

user submit the form and I generate the url to server by _renderUrl()
http://server.com/store?memberId=10&shopId=5

user change the option and submit again
http://server.com/store?memberId=10&shopId=5&memberId=14&shopId=2

user change the option and submit again
http://server.com/store?memberId=10&shopId=5&memberId=14&shopId=2&memberId=20&shopId=6

the query string become longer and longer

[itdpong]

1 more question, I know that the RQL using in dstore was come from here
https://github.com/persvr/rql

area there any php library can extract the RQL query string back into php variables????