Datomic For The 96 Percent

Traditional SQL databases have great power, via ACID transactions and
via a declarative, logic-based query language (SQL). But SQL
databases encounter two problems on the web:

• SQL databases have a rigid information model, and typically a rigid
  deployment model. This rigidity creates impedance mismatches both with
  development languages and with emerging cloud strategies.

• SQL databases struggle with the extremely high write volumes that
  characterize the top four percent of the web, e.g. the Amazons,
  Facebooks, etc.

Much of the effort of the NoSQL movement has gone to solve the second
problem, the problem of the four percent, under the mantra “web scale”.
Datomic solves the first problem – with a flexible information model
and a deployment model suited to the dynamic web, and to the cloud.

Datomic is for the ninety-six percent.

Datomic's information model is based on a universal relation, and an
entity abstraction over that relation. The universal relation
eliminates the join keys and join tables imposed by SQL's plethora of
specific relations, making queries easier to write, read, and
understand. Entities expose the universal relation as associative
collections, which correspond directly to the navigable, associative
style of OO, eliminating the impedance mismatch and the need for
libraries such as ActiveRecord and Hibernate.

Datomic's deployment model is designed for a virtualized world. All
components of the system are designed from the ground up to be
ephemeral. More importantly, Datomic treats storage as a separate
service. You can store your data on the local filesystem during
development, and upgrade to using a SQL database for storage for
production. When you are ready for the cloud, you can store your data
in a distributed storage such as Amazon's DynamoDB, Couchbase, or
Riak.

Datomic's flexibility comes with the expressive power you know and
love in SQL databases. Where the four percent need “web scale”, and
the complex programming model imposed by eventual consistency, most
programs would be better off with the traditional values: ACID
transactions and powerful queries. Datomic gives you these in spades:
transactions always run at the highest isolation level (serialized),
and the Datalog query language has greater expressive power than the
relational algebra at the foundation of SQL.

If you are among the ninety-six percent, and manage transactional data
of record on the web, Datomic may be a good fit for you.