I. Introduction
With the rapid development of information technology such as the Internet, Internet of things (IoT), and cloud computing, a surging amount of massive data are generated anytime and anywhere in various fields such as e-commerce, biomedicine, and financial investment [1]. The scale of these data is growing daily, promoting the advent of the era of big data. As a hot research field, big data brings new challenges and opportunities to the development of information technology on the one hand. Analyzing and processing big data has become a popular technical issue in the industry [2]. Meanwhile, big data itself is still becoming a strategic resource, with which one can become a dominant player in the big data market and even in the field of information technology [3].