In June 1970 Dr. E. F. Codd published the seminal paper, "A Relational Model of Data for Large Shared Data Banks", in the Association of Computer Machinery (ACM) journal, Communications of the ACM. This paper laid the foundation of relational databases and Codd's model got accepted as the definitive model for relational database management systems (RDBMS) across research institutes in all continents.
For the past three decades SQL has been accepted as the standard RDBMS language. There are three key reasons for the longevity of SQL. They are a) Simplicity, b) Strong Mathematical Foundation and c) Adoption (by several vendors). The power of SQL increased tremendously over the past three decades and SQL emerged as the de-facto standard for relational databases.
The NoSQL movement of 1998 supports database implementations that are non-relational data stores of several categories such as document stores, graph databases, key-value stores, multi-valued databases, etc. There are several flavors of NoSQL implementations such as Oracle Corporation’s BerkeleyDB, Google’s BigTable, Apache’s Cassandra, and Amazon’s SimpleDB.
It is very evident that SQL and NoSQL movement are complementary. RDBMS and SQL implementations will continue to thrive in ecosystems that require OLTP support on relational data stores. What Next?