“…In smart cities' environments, different data sources (e.g., Internet of things, IoT, devices, points of interest, POIs, and geographical information systems) can be used to support different objectives (e.g., improving life quality, providing suggestions to city users and operators, and assisting decision makers by means of predictions, simulations, and plans) [3]. One of the major challenges in this context is dealing with the data ingestion process [1, [4][5][6][7], addressing the import and pre-processing of complex multi-dimensional data (historical and real-time data with their metadata, which can be considered as static and real-time data, respectively). Acquired and derived data are stored to be further accessed and exploited for data analytics, dashboards, and visual analytics views [8].…”