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Technologies for Information Systems Part I (10 points) prof. L. Tanca – July 21st, 2017 Available time: 25 minutes Last Name _________________________________________________________________ First Name ________________________________________________________________ Student ID ________________ Signature_______________________________________ 1) Define the concepts of valid time and transaction time in temporal databases also describing their advantages and disadvantages. 2) Describe flow, level, and unitary measures in the data warehouse context. Provide a set of examples.  During this part of the exam, students are not allowed to consult books or notes.  Students should answer the theoretical questions using their own words, in order for the teachers to be able to assess their real level of understanding. Technologies for Information Systems Part II (22 points) prof. L. Tanca – July 21st, 2017 Available Time: 2h 00m Last Name _________________________________________________________________ First Name _______________________________________________________________ Student ID ________________ Signature_______________________________________ PoliTwitter and UniTwitter are two social data prov iders: they collect Twitter data and store them in an internal database . Then, they grant access to this database to their customers . PoliTwitter collects only tweets coming from Europe an users and stores them into a relational database, while UniTwitter collects only tweets coming from American users and stores them into a document-based NoSQL database. UniPoliTwitter, on the contrary, is a company dealing with social data analysis, and has purchased the access to the data sources provided by PoliTwitte r and UniTwitter. Since PoliTwitter and UniTwitter update regularly…