Data and Database Administration Questions and Answers

Answer: B

Correct answer: Database design

Where both roles exist, the data administrator owns the conceptual work - data modelling, definitions, metadata, ownership policy - and the database administrator the technical work, beginning with database design: the physical schema, indexes, storage and tuning.

Answer: B

Correct answer: False

Before and after images belong to the database change log. The transaction log records the essential details of each transaction - its identifier, the time, the terminal, the input values - without the images of the records themselves. The two logs serve recovery together, but the statement has attributed the content of one to the other.

Answer: C

Correct answer: Switch to duplicate database

After a system failure the quickest route back to service is to switch to a duplicate - a mirrored or standby database kept in step with the original - so that operations continue while the failed copy is repaired. Rollforward from a backup and log is the fallback where no duplicate exists, and it takes far longer.

Answer: B

Correct answer: False

Concurrency control exists to prevent exactly that interference. Locking or timestamping ensures that concurrent transactions produce the same result as if they had run one after another, so the database is not compromised. Without concurrency control the statement would be true.

Answer: A

Correct answer: True

Restore and rerun reloads the last backup and reprocesses every transaction since, which needs no before-images and is simple to implement. Its weakness is time: the reprocessing takes as long as the original work did, so it is used only where the transaction volume is modest or the failure rare.

Answer: A

Correct answer: True

A repository holds the metadata - definitions, sources, transformation rules, lineage - that tells an analyst what a figure in the warehouse actually means and where it came from. Without it the warehouse is a collection of numbers nobody can safely interpret, which is why building and maintaining the repository is treated as part of building the warehouse rather than an optional extra.

Answer: B

Correct answer: False

Incorrect data is usually well-formed and plausible - a valid date that is the wrong date, a real address belonging to someone else - so it passes every format check and is discovered only when someone acts on it. This is why quality has to be built in at the point of capture rather than inspected for afterwards.

Answer: C

Correct answer: Missing data elements

Poor data administration shows itself in missing data elements and in the same entity being defined several different ways in different systems. A single definition of an entity and familiarity with the existing data are what good administration produces, so those two cannot be its failures.

Answer: A

Correct answer: Where the before-images are applied to the database

Backward recovery is rollback: the before-images from the log are written back, undoing the transaction’s changes and returning the database to its earlier state. Forward recovery starts from a backup and applies the after-images to bring it up to date.

Answer: C

Correct answer: Read

A shared lock permits reading, and several transactions may hold one on the same item at the same time - reads do not interfere with each other. Any change requires an exclusive lock, which no other transaction may hold in any mode.