In this reddit blog post, the author talks about MD5 key caching and therefore why it is very difficult for them to scale,
Can someone tell me why it would be necessary to use md5 cache keys? I did not understand the reasons, although they explained it as
"A few years ago, we decided to md5 all our cache keys. At the moment memcached (which is what memcachedb is based on) use only keys of a certain length. In fact, the version based on has this limitation. MD5ing of keys was good a solution to this problem, so we thought. "
source
share