Question 1

Which command permanently removes data files that are no longer referenced by a Delta table and older than the retention threshold?

Accepted Answer

VACUUM VACUUM removes unreferenced data files beyond the retention period, reclaiming storage. OPTIMIZE compacts files and ZORDER co-locates data — neither deletes old files.

Question 2

You DROP a managed Delta table in Databricks. What happens to the underlying data files?

Accepted Answer

The files are deleted along with the metadata For a managed table, Databricks controls both metadata and data, so dropping it deletes the underlying files. For an external table, only the metadata is removed and the files remain.

Question 3

Which capability lets you query a previous version of a Delta table?

Accepted Answer

Time Travel Delta Lake Time Travel lets you query earlier versions using VERSION AS OF or TIMESTAMP AS OF, thanks to the transaction log that records every change.

Question 4

Which approach sends an email to the Databricks Job owner whenever the job fails?

Accepted Answer

Setting up an Alert in the Job page Databricks Jobs have built-in alerting configured directly in the job definition, which emails the owner or chosen recipients on status changes, including failures.

Question 5

Which feature of a data lakehouse leads to better data quality than a traditional data lake offers?

Accepted Answer

ACID-compliant transactions ACID-compliant transactions — atomicity, consistency, isolation, durability — keep writes reliable and prevent partial or corrupt data, which is what raises data quality above a plain data lake.

Question 6

Which command writes data into a Delta table while preventing duplicate records from being written?

Accepted Answer

MERGE MERGE performs an upsert — updating rows that match a condition and inserting those that don't — which prevents duplicates. Plain INSERT or APPEND writes add rows unconditionally.

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