Unbuffered queries

When using php_query(), is this buffering all of the results from the query into memory? If so, is there a parameter I can send to make it not buffer the query? I've also seen comments suggesting that a cursor should be used. There doesn't seem to be any way to get access to the internal cursor used by the PHP pgsql libs... or are they referring to doing something like this:
$result = pg_query($conn, "BEGIN; DECLARE s CURSOR FOR SELECT * FROM users; FETCH ALL IN s; END;");

And then after which I could do this:
while ($row = pg_fetch_assoc($result)) { ...}
I don't have a large enough result set in my development or QA environment to run this query within PHP to know if it works or not. Any suggestions would be helpful. Thank you!
Eric Chamberlain