The Components of Datomic
The Storage Service
When you are ready for higher performance and scalability, you will integrate a storage service (available in Pro Edition only). A storage 'service' can be anything from a SQL database, to a key/value store, to a true service like Amazon's DynamoDB. You will still use the peer library described above, but will configure it and the transactor to use one of the external storage protocols. The currently supported protocols are ddb backed by DynamoDB, riak backed by Riak, cass backed by Cassandra, couchbase backed by Couchbase, inf backed by Infinispan, or sql backed by a SQL database (like PostgreSQL).
When using EC2 you can use our prebuilt Amazon AMI transactor. You will need an Amazon AWS account. Our tools will help you configure users, security groups, auto-scaling, metrics, cloud-formation and other details of AWS.
When using Riak, Couchbase, Infinispan or SQL, you will need to stand up the storage system/server yourself, with scripts we provide to help you with e.g. installing the schemas Datomic requires.
Integrated memcached Support
Another feature of the Pro Edition is optional memcached support. Simply configure the transactor and peers with your memcached servers and they will be transparently utilized as a distributed backing cache for data segments.
You can move an application from the memory database, to dev mode, to a storage-service based configuration with a switch of the connection string on the peers and a properties file on the transactor. All are fully API-compatible. You can move databases between storages with the backup/restore facilities.