Cloud computing is a rapidly evolving technology in terms of speed, scalability, and efficiency. Thanks to open-source software becoming an integral part of the cloud, this is mainly happening. Just to name a few, your candidate should be familiar with MongoDB, CouchDB, and LucidDB. The first one, MongoDB, is written in C++, and it offers high storage capabilities. Also, this database system is schema-free and document-oriented. On the other hand, CouchDB is based on an Apache server and is very efficient and reliable at its job (which is storing data). Finally, we find LucidDB, employed for data warehousing, and it is written in Java/C++.