  Outsourcing databases, i.e., resorting to Database-as-a-Service (DBaaS), is
nowadays a popular choice due to the elasticity, availability, scalability and
pay-as-you-go features of cloud computing. However, most data are sensitive to
some extent, and data privacy remains one of the top concerns to DBaaS users,
for obvious legal and competitive reasons.In this paper, we survey the
mechanisms that aim at making databases secure in a cloud environment, and
discuss current pitfalls and related research challenges.
