title: Copying all keys in Redis database using MIGRATE
body: <p>Is it possible to copy all keys from one Redis instance to another remote instance using <code>MIGRATE</code>? I've tried <code>COPY</code>, <code>REPLACE</code> and <code>KEYS</code> without any luck. Each time I get a <code>NOKEY</code> response. If I use any of the <code>MIGRATE</code> commands with a single key it works.</p>
  
  <p>Examples:</p>
  
  <pre><code>MIGRATE my.redis 6379 "*" 0 5000 REPLACE // NOKEY
  MIGRATE my.redis 6379 "*" 0 5000 COPY // NOKEY
  MIGRATE my.redis 6379 "" 0 5000 KEYS * // NOKEY
  
  MIGRATE my.redis 6379 "" 0 5000 KEYS test // OK
  </code></pre>