Oracle 5.0 Reference Manual page 1353

Deploying a MySQL Database Using EC2
Using within your EC2 instances should provide better performance. The large and extra
memcached
large instances have a significant amount of RAM. To use in your application, when
memcached
loading information from the database, first check whether the item exists in the cache. If the data you
are looking for exists in the cache, use it. If not, reload the data from the database and populate the
cache.
Sharding divides up data in your entire database by allocating individual machines or machine groups
to provide a unique set of data according to an appropriate group. For example, you might put all users
with a surname ending in the letters A-D onto a single server. When a user connects to the application
and their surname is known, queries can be redirected to the appropriate MySQL server.
When using sharding with EC2, separate the web server and MySQL server into separate EC2
instances, and then apply the sharding decision logic into your application. Once you know which
MySQL server you should be using for accessing the data you then distribute queries to the
appropriate server. You can see a sample of this in the following illustration.
1333