MC	Which statement is CORRECT?	Outdated and inconsistent data is a key risk when working with a virtual data warehouse or virtual data mart.	incorrect	In terms of data manipulation, a data warehouse focusses on Insert/Update/Delete/Select statements.	incorrect	A data lake is less agile compared to a data warehouse which has no structure.	incorrect	OLAP allows you to interactively analyze the data, summarize it, and visualize it in various ways	correct	
MC	In terms of data manipulation, a data warehouse focusses on...	Select/Update statements	incorrect	Insert/Update/Delete/Select statements	incorrect	Insert/Select statements	correct	Delete statements	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	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	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	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	
MC	Which statement is NOT CORRECT?	Query and reporting tools are an essential component of a comprehensive business intelligence solution.	incorrect	The key fundament of OLAP is a multidimensional data model which can be implemented in various ways.	incorrect	A pivot or cross-table is a popular data summarization tool.  It essentially cross-tabulates a set of dimensions.	incorrect	A key disadvantage of OLAP is that it does not allow to interactively analyze your data, summarize it and visualize it in various ways.	correct	
MC	Which statement is NOT CORRECT?	A factless fact table is a fact table which only contains foreign keys and no measurement data.	incorrect	In a data warehouse context, an outrigger table can be defined to store a set of attribute types of a dimension table which are not correlated, high in cardinality and updated sequentially.	correct	The data schema de?nitions in a data lake are only determined when the data are read (schema-on-read) instead of when the data are loaded (schema-on-write) as is the case for a data warehouse. 	incorrect	During the loading step of the ETL process, the data warehouse is populated by filling the fact and dimension tables. Dimension rows should be inserted/updated before the fact rows are inserted/updated.	incorrect	
MC	Which statement is CORRECT?	In case of a data warehouse, the data schema definitions are only determined when the data is read (schema-on-read) whereas for data lakes it is fixed when the data is loaded (schema-on-write).	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	A key distinguishing property of a data lake is that it stores raw data in its native format which could be structured, unstructured or semi-structured.	correct	A data lake is less agile compared to a data warehouse which has no structure.	incorrect	
MC	Which statement is NOT CORRECT?	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	A key advantage of virtualization is that it requires no extra processing capacity from the underlying (operational) data stores.	correct	A virtual data warehouse (sometimes also called a federated database) or virtual data mart contains no physical data but provides a uniform and consolidated single point of access to a set of underlying physical data stores.	incorrect	A data mart is a scaled down version of a data warehouse aimed at meeting the information needs of a homogeneous small group of end-users such as a department or business unit (e.g., marketing, finance, logistics, HR, etc.).	incorrect	
MC	Which statement is CORRECT?	A data lake is less agile compared to a data warehouse which has no structure.	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	In case of a data warehouse, the data schema definitions are only determined when the data is read (schema-on-read) whereas for data lakes it is fixed when the data is loaded (schema-on-write).	incorrect	A key distinguishing property of a data lake is that it stores raw data in its native format which could be structured, unstructured or semi-structured.	correct	
MC	Which of the following is not a characteristic of a data warehouse?	Subject-oriented	incorrect	Volatile	correct	Time-variant	incorrect	Integrated	incorrect	
MC	Which statement is NOT CORRECT?	A charecteristic of data warehouses is that they are volatile.	correct	When choosing the granularity of the fact table, a trade-off between the level of detailed analysis and storage requirements (and hence query performance) must be made.	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	During the loading step of the ETL process, the data warehouse is populated by filling the fact and dimension tables. Dimension rows should be inserted/updated before the fact rows are inserted/updated.	incorrect