  NoSQL databases are becoming increasingly popular as more developers seek new
ways for storing information. The popularity of these databases has risen due
to their flexibility and scalability needed in domains like Big Data and Cloud
Computing. This paper examines asynchronous replication, one of the key
features for a scalable and flexible system. Three of the most popular
Document-Oriented Databases, MongoDB, CouchDB, and Couchbase, are examined. For
testing, the execution time for CRUD operations for a single database instance
and for a distributed environment with two nodes is taken into account and the
results are compared with tests outcomes obtained for three relational database
management systems: Microsoft SQL Server, MySQL, and PostgreSQL.
