Buffer copy data messages (#265)

* Buffer copy data messages

* Update comment

src/server.rs

@@ -510,9 +510,13 @@ impl Server {
                     break;
                 }
 
-                // CopyData: we are not buffering this one because there will be many more
-                // and we don't know how big this packet could be, best not to take a risk.
-                'd' => break,
+                // CopyData
+                'd' => {
+                    // Don't flush yet, buffer until we reach limit
+                    if self.buffer.len() >= 8196 {
+                        break;
+                    }
+                }
 
                 // CopyDone
                 // Buffer until ReadyForQuery shows up, so don't exit the loop yet.