diff --git a/sstables/key.hh b/sstables/key.hh
index 000bda3090..c2af2c68e2 100644
--- a/sstables/key.hh
+++ b/sstables/key.hh
@@ -6,6 +6,7 @@
 #include "bytes.hh"
 #include "schema.hh"
 #include <boost/any.hpp>
+#include "core/future.hh"
 
 class partition_key;
 class clustering_key;
@@ -112,10 +113,14 @@ class composite {
     bytes _bytes;
 public:
     composite (bytes&& b) : _bytes(std::move(b)) {}
+    template <typename Describer>
+    future<> describe_type(Describer f) const { return f(const_cast<bytes&>(_bytes)); }
+
     static composite from_bytes(bytes b) { return composite(std::move(b)); }
     static composite from_clustering_key(const schema& s, const clustering_key& ck);
     static composite from_exploded(const std::vector<bytes_view>& v);
     static composite static_prefix(const schema& s);
+    size_t size() const { return _bytes.size(); }
     explicit operator bytes_view() const {
         return _bytes;
     }