Databases are the core of all the business services that are offered online. Cloud computing has drastically changed the way these online services are being offered. Hence it is of significance importance that the databases need to be compatible with cloud computing. The data is growing enormously with every passing day. With the paradigm shift in the technology used to store, manage and retrieve the data from file storage to relational databases to today's cloud databases, the need to process the query efficiently while preserving the privacy had always been the priority. The dynamism of the query and the optimization of the resources used for query execution are the aspects that doesn't change in any situation. The timing constraint on the query execution could be either instantaneous, urgent, leisurly or indefinite. But in almost all the scenarios the effective storage, manipulation and data retrieval is the key. While retrieving the data stored in cloud, privacy preservation is of utmost importance. To improve query efficiency in cloud with preserving the privacy can be achieved by introducing dataflow optimization techniques and defining data descriptor based algorithms.