Distributed query optimization strategies for cloud environment

Cloud computing services are provided over the internet such as computing, servers, storage, databases, networking, software, and many more. Then, customers get services from cloud providers and pay according to their usage. Nowadays, Database as a service is becoming a more popular service in cloud computing. Due to faster response and more reliability, distributed databases are used in the cloud for storing and managing data. Thus, enterprises are transferring the stored data to the cloud computing center. Although in a distributed database system via cloud environment, the required relations by a query plan may be stored at numerous sites. This exponentially increases the number of potential equivalent plan alternatives to find an optimal Query Execution Plan. Although exhaustively explore all potentials plans in large search space is not computationally reasonable. Therefore, in order to improve the performance in the cloud, query optimization mechanisms are paramount and required in order to optimize data processing time and maximize resource utilization. So, a review of the different techniques used for query optimization is conducted in this paper to provide researchers with a complete view of query processing and its optimization techniques. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2021.