<p>Is there a limit to the length of a GET request?</p>

Not in the
RFC
, no, but there are practical limits.
The HTTP protocol does not place any a priori limit on the length of
a URI. Servers MUST be able to handle the URI of any resource they
serve, and SHOULD be able to handle URIs of unbounded length if they
provide GET-based forms that could generate such URIs. A server
SHOULD return 414 (Request-URI Too Long) status if a URI is longer
than the server can handle (see section 10.4.15).
Note: Servers should be cautious about depending on URI lengths
above 255 bytes, because some older client or proxy implementations
may not properly support these lengths.