Michael Otey explains why NoSQL isn’t really a viable replacement for SQL Server -
The term “NoSQL” was coined back in 1998, and it originally stood for Not Only SQL. So the name NoSQL is a bit of a misnomer.
NoSQL databases aren’t relational at all.
Today’s NoSQL databases are distributed data stores that are designed for very large-scale data access requirements. Probably the most popular NoSQL database is the Cassandra open source project. Cassandra began as Facebook’s proprietary database, but Facebook released it as open source in 2008.
Other NoSQL implementations include Google BigTable, Apache Hadoop, MapReduce, MemcacheDB, and Voldemort.
...though NoSQL databases are designed for performance and scalability, they aren’t designed to support the atomicity, consistency, isolation, and durability (ACID) properties that are standard in relational databases such as SQL Server....each different NoSQL implementation uses a proprietary data access mechanism.
SQL Server DBAs don’t need to fear that NoSQL represents some new technology wave that will sweep away relational databases like SQL Server. Instead NoSQL is just another tool in the application developer’s toolbox.
NoSQL implementations solve a data storage problem that relational databases weren’t really designed to address. So the bottom line on NoSQL is that NoSQL isn’t a technology that’s going to replace relational database systems like SQL Server—except in very specialized instances.