Database Reference
In-Depth Information
the application code. Sharded databases make the operational tasks (backup, schema alter-
ation, and adding index) difficult. To find out more about the hardships of sharding, visit
There are ways to loosen up consistency by providing various isolation levels, but concur-
rency is just one part of the problem. Maintaining relational integrity, difficulties in man-
aging data that cannot be accommodated on one machine, and difficult recovery, were all
making the traditional database systems hard to be accepted in the rapidly growing big
data world. Companies needed a tool that could support hundreds of terabytes of data on
the ever-failing commodity hardware reliably. This led to the advent of modern databases
like Cassandra, Redis, MongoDB, Riak, HBase, and many more. These modern databases
promised to support very large datasets that were hard to maintain in SQL databases, with
relaxed constrains on consistency and relation integrity.
