Data in the data warehouse are loaded and refreshed from operational systems.
Answer: A
Correct answer: True
The warehouse is not entered directly; it is filled from the operational systems by the ETL process and refreshed periodically thereafter. This is why it is described as non-volatile from the user’s point of view - end users read it and never update it.
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Reconciled data is which of the following?
Answer: B
Correct answer: Current data intended to be the single source for all decision support systems.
Reconciled data is the detailed, current, integrated layer that results from extracting and cleaning the operational sources - the enterprise data warehouse itself. It is normalised and not usually queried directly; derived data, formatted for particular user applications, is what the data marts hold.
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Fact tables are which of the following?
Answer: C
Correct answer: Completely normalized
The fact table holds the measures and the foreign keys to the dimensions, and nothing that could be moved elsewhere - so it is fully normalised. It is the dimension tables that are deliberately denormalised, since flattening them reduces the joins a query must perform, at a cost in redundancy that a read-only store can afford.
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Both status data and event data can be stored in a database.
Answer: A
Correct answer: True
Status data record what something is at a point in time - a balance, an address, a price. Event data record that something happened - a payment, a change of address. Both are held, and the distinction matters because a status can often be reconstructed from a sequence of events, and vice versa.
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Derived data are detailed, current data intended to be the single, authoritative source for all decision support applications.
Answer: A
Correct answer: False
Detailed, current data intended as the single authoritative source is reconciled data - the warehouse itself. Derived data is what has been selected, aggregated and formatted for particular end-user applications, and it is what the data marts hold.
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Data scrubbing can help upgrade data quality; it is not a long-term solution to the data quality problem.
Answer: A
Correct answer: True
Scrubbing improves the data going into the warehouse but leaves the source systems producing the same errors next time, so the cleaning must be repeated at every load. The lasting remedy is to correct the operational processes, which is why quality is treated as a management programme rather than a stage in ETL.
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A multifield transformation does which of the following?
Answer: D
Correct answer: All of the above
A multifield transformation is one whose input or output spans more than one field, and all three patterns qualify - splitting a full name into parts, combining separate address lines into one, or mapping several fields onto several others. What distinguishes it is the crossing of field boundaries, not the direction.
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A goal of data mining includes which of the following?
Answer: A
Correct answer: To explain some observed event or condition
Data mining is exploratory: it looks for patterns and relationships that were not anticipated, and so can suggest why something happened. This is what distinguishes it from ordinary querying, which confirms relationships already expected - the second and third options describe verification rather than discovery.
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Joining is the process of partitioning data according to predefined criteria.
Answer: B
Correct answer: False
Joining combines data from several sources into a single record; the process described - partitioning according to predefined criteria - is selection. Both are transformation operations, and the statement has attached the definition of one to the name of the other.
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A data warehouse is which of the following?
Answer: C
Correct answer: Organized around important subject areas.
Subject orientation is the first of the defining characteristics: the warehouse is arranged around customer, product or sale rather than around the applications the data came from. The other options describe an operational system - it is the warehouse that is integrated, non-volatile and time-variant.
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