RAM Cache - use different cache "buckets" based on URI string

Just one approach;-

when HTTP_REQUEST {
    if {[URI::query [HTTP::uri]] contains "mykey="} {
        set newq ""
        foreach param [split [URI::query [HTTP::uri]] "&"] {
            if {!($param starts_with "mykey=")} {
                     Build up new query parameter string
                append newq $param
            }
             Add new query portion to path
            HTTP::uri "[HTTP::path]$newq"
        }
    }