Database Reference
In-Depth Information
clearly not a solution, and that's where the need for NoSQL databases arises. The best
way to adopt databases is to understand the requirements first. If the application is
polyglot in nature, then you may need to choose more than one database from the
available options. In the next section, we will discuss a few points that describe why
Cassandra could be an answer to your big data problem.
CAP Theorem
CAP theorem, which was introduced in early 2000 by Eric Brewer, states that no data-
base can offer
Consistency, Availability,
and
Partition tolerance
together (see
Figure
Figure 1-1
.
CAP theorem excludes the possibility of a database with all three characteristics (the “NA” area)
Traditional relational database management systems (RDBMS) provide atomicity,
consistency, isolation, and durability (ACID) semantics and advocate for strong con-
sistency. That's where most of NoSQL databases differ and strongly advocate for parti-
tion tolerance and high availability with eventual consistency.
High availability
of data means data must be available with minimal
latency. For distributed databases where data is distributed across
multiple nodes, one way to achieve high availability is to replicate it
across multiple nodes. Like most of NoSQL databases, Cassandra
also provides high availability.
