about GET: how much I can GET?

[realMakc]

ftp://ftp.rfc-editor.org/in-notes/rfc2616.txt

10.4.15 414 Request-URI Too Long

The server is refusing to service the request because the Request-URI
is longer than the server is willing to interpret. This rare
condition is only likely to occur when a client has improperly
converted a POST request to a GET request with long query
information, when the client has descended into a URI "black hole" of
redirection (e.g., a redirected URI prefix that points to a suffix of
itself), or when the server is under attack by a client attempting to
exploit security holes present in some servers using fixed-length
buffers for reading or manipulating the Request-URI.

Это означает, что максимум зависит от сервера.