Task 1 5 Marks In this task, we will practice the authentication and user/role management in NEO4J. You can read more about authentication and authorization in NEO4J under this url: https://neo4j.com/docs/operations-manual/3.3/security/ authentication-authorization/. You can use an empty database or an existing database, which was used in previous tasks.

If at any point you do not have access any more, because you do not know the password to your database, try deleting the file auth, which is located in Neo4j Home/data/dbms/

(a) List the built-in roles in NEO4J. What is the difference between editor and architect roles.

(b) Log in as admin. Write Cypher statements to create a new user student and assign the role reader to him.

(c) Log in as student. Write a Cypher statement to check if it is possible to create a new node, and explain your result.

(d) Write Cypher statements to revoke the role reader from a user student and assign the new role publisher to him, then try again to create a new node using user student.

(e) Write a Cypher statement to list all users with their current roles, then delete the user student.

Task 2 3 Marks In this task, we will practice the Hippocratic databases and learn their principles. You can read more about Hippocratic databases in the research paper under this url: http: //www.vldb.org/conf/2002/S05P02.pdf

(a) Explain the difference between limited disclosure and limited retention.

(b) Suppose your favorite social network wants to use a Hippocratic database. Which privacy authorizations (including purposes, tables/attributes, authorized users) would you recommend?

(c) Draw a purpose DAG for your example

Task 3 2 Marks In this task we will practice the indexes in Neo4j. You can read more about indexes under this url: http://neo4j.com/docs/developer-manual/current/cypher/schema/ index/.

(a) Write a cypher query to create a composite-index on the name, birthplace properties for all nodes that have a Actor label. Datenbanken II 3

(b) Explain in your words how using the index may effect the performance of retrieving data from database