I. Introduction
Smart cities generate huge amounts of data from numerous connected devices (sensors, vehicles, actuators, etc) and applications (traffic management, healthcare system, stock exchange data, e-shopping, etc.) which are transmitted to geolocated sites for processing or storage [1]. For example, in the healthcare sector, a large amount of medical images and data are generated and stored for use in online medical health records. Similarly, at the consumer end, the content (images, videos, etc.) is generated via social networks for creating a highly connected society. Another example is that of smart meters, deployed at each household, capture the energy usage data continuously thereby generating a multithousand fold data. These kinds of multihundred or multithousand petabyte data sets are creating a new horizon of opportunities in diverse application domains like human genomics, healthcare systems, finance and banking, oil and natural gas exploration, and many more. These data being huge in amount (volume), variable in type and structure (velocity), and generated at different rates or times (variety) have to be analyzed using sophisticated algorithms or big data solutions for identifying hidden patterns which can further lead to several benefits related to decision making in smart ecosystems [2]. In simple words, big data technologies and architectures are designed to extract economical value from a large amount of variable data through high-velocity capture, discover, or analyze process [3].