Relational databases have been around for many decades and are the database technology of choice for most traditional data-intensive storage and retrieval applications. Retrievals are usually accomplished using SQL, a declarative query language. Relational database systems are generally efficient unless the data contains many relationships requiring joins of large tables. Recently there has been much interest in data stores that do not use SQL exclusively, the so called NoSQL movement. Examples are Google’s BigTable and Facebook’s Cassandra. Lets have a look at NoSQL vs MySQL (common relational database system).
When to go for NOSQL ??
In recent years, software developers have been investigating storage alternatives to relational databases. NoSQL is a blanket term for some of those new systems. Cassandra,BigTable, CouchDB, Project Voldemort, and Dynamo are all NoSQL projects, as they are all high-volume data stores that actively reject the relational and object-relational models.
Atomicity, consistency, isolation, and durability (ACID) are a set of governing principles of the relational model. Together, they guarantee database reliability. NoSQL rejects ACID.
The term “NoSQL,” as a term for modern web data stores,first began to gain popularity in early 2009. It is a topic that has gained recognition from the IT community but has yet to garner large-scale academic study. Still, the NoSQL movement has its own discussion groups, blogs, and conferences.
As the typical database administrator attempts to question whether to move from the relational model to a NoSQL model, the NoSQL community presents him or her with potential flags that the data might be more suitable for a NoSQL system.
- Having tables with lots of columns, each of which is only used by a few rows.
- Having attribute tables.
- Having lots of many-to-many relationships.
- Having tree-like characteristics.
- Requiring frequent schema changes.