MC	Which statement is NOT CORRECT?	Slicing represents the operation whereby one of the dimensions is set at a particular value.	incorrect	In terms of data manipulation, a data warehouse focusses on Delete statements.	correct	A pivot or cross-table is a popular data summarization tool.  It essentially cross-tabulates a set of dimensions.	incorrect	In a fact constellation schema, more than one fact table is used.	incorrect	
MC	Which statement is CORRECT?	One way to deal with a rapidly changing dimension in a data warehouse context is by splitting all information into stable and rapidly changing information and put the latter into a separate mini-dimension table with a new surrogate key.  Both tables can then be connected by a introducing an additional table.	correct	In the context of an ETL process, an incremental extraction strategy only extracts data from specific business units.	incorrect	A data lake is targeted towards decision makers at middle and top management level, whereas a data warehouse requires a data scientist, which is a more specialized profile in terms of data handling and analysis.	incorrect	Outdated and inconsistent data is a key risk when working with a virtual data warehouse or virtual data mart.	incorrect	
MC	In terms of data manipulation, a data warehouse focusses on...	Insert/Select statements	correct	Delete statements	incorrect	Select/Update statements	incorrect	Insert/Update/Delete/Select statements	incorrect	
MC	Which statement is CORRECT?	The dimension tables of a star schema contain the criteria for aggregating the measurement data and will typically be used as constraints to answer queries.	correct	A star schema has one large central dimension table which is connected to various smaller fact tables.	incorrect	The dimension tables in a star schema are frequently updated.	incorrect	To speed up report generation and avoid time consuming joins in a star schema, the dimension tables need to be normalized.	incorrect	
MC	Which statement is NOT CORRECT?	At the operational level, day to day business decisions are made, typically in real-time or with a short time frame.	incorrect	A data warehouse provides a centralized, consolidated data platform by integrating data from different sources and in different formats.  As such, it provides a separate and dedicated environment for operational decision making.	correct	At the tactical level, decisions are made by middle management with a medium-term (e.g. a month, a quarter, a year) focus.	incorrect	At the strategic level, decisions are made by senior management with long term implications (e.g., 1, 2, 5 years or more)	incorrect	
MC	Which statement is NOT CORRECT?	To speed up report generation and avoid time consuming joins in a star schema, the dimension tables need to be normalized.	correct	Business keys usually have a business meaning that may change over time.	incorrect	In OLAP, Windowing allows calculating cumulative totals or running averages based on a speci?ed window of values	incorrect	Dependent data marts pulls their data from a central data warehouse, whereas independent data marts are standalone systems drawing data directly from the operational systems, external sources or a combination of both.	incorrect	
MC	Which statement is NOT CORRECT?	In terms of data manipulation, a data warehouse focusses on Insert/Select statements.	incorrect	Slowly changing dimensions in a data warehouse environment can be tackled by adding a new attribute type to the table such that only the most recent and previous value of it are stored. 	incorrect	The GROUPING SETS OLAP operator generates a result set equivalent to that generated by an INTERSECT of multiple simple GROUP BY clauses.	correct	Surrogate keys are typically meaningless integers, used as foreign keys to connect the fact to the dimension tables.	incorrect	
MC	Which statement is NOT CORRECT?	Relational OLAP (ROLAP) stores the data in a relational data warehouse, which can be implemented using a star, snowflake or fact constellation schema.	incorrect	MOLAP scales better to more dimensions than ROLAP.  The query performance may however be inferior to ROLAP unless some of the queries are materialized or high-performance indexes are defined.	correct	Multidimensional OLAP (MOLAP) stores the multidimensional data using a Multidimensional DBMS (MDBMS) whereby the data is stored in a multi-dimensional array-based data structure optimized for efficient storage and quick access.	incorrect	Hybrid OLAP (HOLAP) tries to combine the best of both MOLAP and ROLAP.  An RDBMS can then be used to store the detailed data in a relational data warehouse whereas the pre-computed aggregated data can be kept as a multidimensional array managed by a MDBMS.	incorrect	
MC	Which statement is NOT CORRECT?	Some estimates state that the ETL step can consume up to 80% of all efforts needed to set up a data warehouse.	incorrect	During the loading step of ETL, the data warehouse is populated by filling the fact and dimension tables hereby also generating the necessary surrogate keys to link it all up.  Fact rows should be inserted/updated before the dimension rows.	correct	To decrease the burden on both the operational systems and the data warehouse itself, it is recommended to start the ETL process by dumping the data in a staging area where all the ETL activities can be executed.	incorrect	The extraction strategy of ETL can be either full or incremental.  In the latter case, only the changes since the previous extraction are considered.	incorrect	
MC	Which statement is NOT CORRECT?	Surrogate keys essentially buffer the data warehouse from the operational environment by making it immune to any operational changes.	incorrect	A factless fact table is a fact table which only contains foreign keys and no measurement data.	incorrect	A fact constellation schema has more than one fact table which can share dimension tables.	incorrect	A snowflake schema normalizes the fact table of a star schema.	correct