Databricks Certified Data Engineer Professional Practice Test 30
Question 290
Quality assurance at Silver Ridge Logistics checks a corrected workload where an aggregation workload has one very slow Spark stage. The original fault was: Operators only monitor cluster-wide CPU and miss skewed task durations. Which verification is most decisive?
- Trigger a controlled failure and confirm notification delivery
- Re-run and confirm shuffle spill and maximum task time decrease
- Cause a safe test failure and confirm exactly one incident is created
- Run an on-time and delayed batch and verify measured lag matches reality
Explanation
Correct Answer
B:Re-run and confirm shuffle spill and maximum task time decrease. This tests the expected result against operators only monitor cluster-wide CPU and miss skewed task durations, not simply whether a job or object exists. Spark UI stage metrics reveal shuffle, spill and task skew.
Incorrect Answers
A:Trigger a controlled failure and confirm notification delivery. This validate action addresses a different case (job email notification), where operators manually check the run page every morning. Lakeflow Jobs support status-triggered notifications for run outcomes. In the stated problem, operators only monitor cluster-wide CPU and miss skewed task durations; this choice would not establish the required spark ui shuffle metrics decision.
C:Cause a safe test failure and confirm exactly one incident is created. This validate action addresses a different case (job webhook destination), where only personal email notifications are configured. Supported job notification destinations can integrate workflow status with an incident system. In the stated problem, operators only monitor cluster-wide CPU and miss skewed task durations; this choice would not establish the required spark ui shuffle metrics decision.
D:Run an on-time and delayed batch and verify measured lag matches reality. This validate action addresses a different case (end-to-end sla), where operators monitor compute uptime rather than data freshness. SLA monitoring should measure source event time to published table availability. In the stated problem, operators only monitor cluster-wide CPU and miss skewed task durations; this choice would not establish the required spark ui shuffle metrics decision.
Question 291
Quality assurance at Summit Consumer Goods checks a corrected workload where an orchestrator retries a failed object-storage batch. The original fault was: A partially processed input file is loaded twice into Delta. Which verification is most decisive?
- Restart the job and verify no duplicate committed records
- Ingest old and new samples and verify nested fields and rescued data are retained
- Replay the failed batch and verify each source event appears once
- Append one new object and verify it is ingested only once
Explanation
Correct Answer
C:Replay the failed batch and verify each source event appears once. This tests the expected result against a partially processed input file is loaded twice into Delta, not simply whether a job or object exists. Checkpointed incremental ingestion or stable event-level deduplication prevents repeated effects.
Incorrect Answers
A:Restart the job and verify no duplicate committed records. This validate action addresses a different case (kafka offset durability), where restarting with a fresh checkpoint replays previously ingested messages. A stable streaming checkpoint maintains Kafka offsets and sink progress across restarts. In the stated problem, a partially processed input file is loaded twice into Delta; this choice would not establish the required retry-safe file loads decision.
B:Ingest old and new samples and verify nested fields and rescued data are retained. This validate action addresses a different case (nested json ingest), where the initial reader assumes one unchanging flat schema and loses new fields. Explicit schema management and rescued data handling protect evolving semi-structured ingestion. In the stated problem, a partially processed input file is loaded twice into Delta; this choice would not establish the required retry-safe file loads decision.
D:Append one new object and verify it is ingested only once. This validate action addresses a different case (auto loader file discovery), where listing the full historical directory every run exceeds the ingestion SLA. Auto Loader is designed for incremental new-file discovery with persisted state. In the stated problem, a partially processed input file is loaded twice into Delta; this choice would not establish the required retry-safe file loads decision.
Question 292
At Clearstone Media, a central dashboard must display status for hundreds of workflows. Observed issue: A manual UI report omits failed tasks and paginated runs. Before applying a fix, which investigation is most directly relevant?
- Inspect Query Profile operators for scan volume and pruning
- Inspect run intervals, executor utilization and billed usage
- Inspect event log messages, error class and dataset name around the failed update
- Inspect endpoint permissions and run-list pagination behavior
Explanation
Correct Answer
D:Inspect endpoint permissions and run-list pagination behavior. This checks the specific evidence behind a manual UI report omits failed tasks and paginated runs. The Jobs API exposes run records that a program can paginate and aggregate. The investigation distinguishes the mechanism from an unrelated operational symptom.
Incorrect Answers
A:Inspect Query Profile operators for scan volume and pruning. This diagnose action addresses a different case (query profile scans), where operators assume the query is always CPU-bound. Query Profile identifies scan, pruning and shuffle behavior for SQL workloads. In the stated problem, a manual UI report omits failed tasks and paginated runs; this choice would not establish the required jobs rest monitoring decision.
B:Inspect run intervals, executor utilization and billed usage. This diagnose action addresses a different case (compute utilization), where most provisioned resources sit idle between job runs. Compute metrics and usage history distinguish idle capacity from active work. In the stated problem, a manual UI report omits failed tasks and paginated runs; this choice would not establish the required jobs rest monitoring decision.
C:Inspect event log messages, error class and dataset name around the failed update. This diagnose action addresses a different case (pipeline event log), where the Jobs status only reports a high-level failure. Lakeflow pipeline event logs include update-level errors and progress events. In the stated problem, a manual UI report omits failed tasks and paginated runs; this choice would not establish the required jobs rest monitoring decision.
Question 293
At Summit Consumer Goods, a nightly compliance job is owned by an individual with broad administrator permissions. A change is required because: The individual's credentials create unnecessary privilege and lifecycle risk. Which implementation action most directly corrects the configuration?
- Change the job run-as principal and validate the required data permissions
- Grant only required read privileges on the external location
- Create the aggregation view and grant SELECT only on the view
- Revoke unnecessary production ownership and grant task-specific roles
Explanation
Correct Answer
A:Change the job run-as principal and validate the required data permissions. This directly changes the feature or logic behind the individual's credentials create unnecessary privilege and lifecycle risk. Production automation should use least-privilege service principals for stable identity. It is the concrete configuration for the stated incident.
Incorrect Answers
B:Grant only required read privileges on the external location. This implement action addresses a different case (storage credential scope), where engineers propose a credential allowing access to all company buckets. Unity Catalog storage credentials and external locations can constrain storage access. In the stated problem, the individual's credentials create unnecessary privilege and lifecycle risk; this choice would not establish the required service principal access decision.
C:Create the aggregation view and grant SELECT only on the view. This implement action addresses a different case (secure view sharing), where granting SELECT on the raw fact table violates minimization. A governed aggregation view can expose only approved derived information. In the stated problem, the individual's credentials create unnecessary privilege and lifecycle risk; this choice would not establish the required service principal access decision.
D:Revoke unnecessary production ownership and grant task-specific roles. This implement action addresses a different case (separation of duties), where all developers currently own production catalogs and can grant access. Separate deploy and governance roles reduce accidental privilege escalation. In the stated problem, the individual's credentials create unnecessary privilege and lifecycle risk; this choice would not establish the required service principal access decision.
Question 294
At Summit Consumer Goods, a nightly compliance job is owned by an individual with broad administrator permissions. A change was deployed to address: The individual's credentials create unnecessary privilege and lifecycle risk. Which test result provides the strongest evidence that the requirement is now met?
- Confirm reader cannot edit but approved maintainer can deploy
- Run the job using the principal and confirm forbidden datasets remain blocked
- Run with test credentials and confirm logs contain no secret strings
- Trigger a test error and confirm logs reveal no PII content
Explanation
Correct Answer
B:Run the job using the principal and confirm forbidden datasets remain blocked. This tests the expected result against the individual's credentials create unnecessary privilege and lifecycle risk, not simply whether a job or object exists. Production automation should use least-privilege service principals for stable identity.
Incorrect Answers
A:Confirm reader cannot edit but approved maintainer can deploy. This validate action addresses a different case (workspace object acl), where the team needs read-only access for most users. Workspace object permissions can restrict who can edit or manage shared code. In the stated problem, the individual's credentials create unnecessary privilege and lifecycle risk; this choice would not establish the required service principal access decision.
C:Run with test credentials and confirm logs contain no secret strings. This validate action addresses a different case (secret retrieval logs), where databricks notebook redaction is incorrectly treated as a comprehensive security control. Secrets should never be deliberately printed or put in logs, regardless of redaction behavior. In the stated problem, the individual's credentials create unnecessary privilege and lifecycle risk; this choice would not establish the required service principal access decision.
D:Trigger a test error and confirm logs reveal no PII content. This validate action addresses a different case (restricted event logging), where logs expose PII to broader operations readers. Logging should redact or omit sensitive payload fields while preserving diagnostic codes. In the stated problem, the individual's credentials create unnecessary privilege and lifecycle risk; this choice would not establish the required service principal access decision.
Question 295
At Westridge Research, a gold revenue table shows a monthly discrepancy. Architecture constraint: Investigators cannot tell which upstream transformation produced it. Which design best addresses this requirement?
- Use a durable steward group as owner rather than a personal principal
- Define a metadata quality standard for business purpose, grain and sensitivity
- Use lineage alongside data-quality checks to trace source-to-output transformations
- Choose approved managed storage locations for governed tables
Explanation
Correct Answer
C:Use lineage alongside data-quality checks to trace source-to-output transformations. This design addresses investigators cannot tell which upstream transformation produced it. Unity Catalog lineage records relationships between governed data assets. It establishes the right contract or architecture before execution changes.
Incorrect Answers
A:Use a durable steward group as owner rather than a personal principal. This design action addresses a different case (ownership reassignment), where new data stewards cannot maintain its grants. Unity Catalog ownership should be assigned to a maintained principal. In the stated problem, investigators cannot tell which upstream transformation produced it; this choice would not establish the required lineage tracking decision.
B:Define a metadata quality standard for business purpose, grain and sensitivity. This design action addresses a different case (catalog descriptions), where table and column metadata lack meaningful descriptions. Unity Catalog comments improve discoverability of governed data assets. In the stated problem, investigators cannot tell which upstream transformation produced it; this choice would not establish the required lineage tracking decision.
D:Choose approved managed storage locations for governed tables. This design action addresses a different case (managed storage ownership), where the data platform cannot apply consistent lifecycle governance. Managed locations centralize storage ownership for Unity Catalog managed assets. In the stated problem, investigators cannot tell which upstream transformation produced it; this choice would not establish the required lineage tracking decision.
Question 296
A data engineer at Eastern Star Foods must troubleshoot this case: a cloud object store receives a large and growing set of landing files. Evidence: Listing the full historical directory every run exceeds the ingestion SLA. What should be inspected first to confirm the failure mechanism?
- Inspect write modes and table-history operations around the loss
- Inspect duplicate file IDs and the ingestion checkpoint state
- Inspect representative raw lines and parser quote/escape settings
- Inspect file-discovery backlog and the source format configuration
Explanation
Correct Answer
D:Inspect file-discovery backlog and the source format configuration. This checks the specific evidence behind listing the full historical directory every run exceeds the ingestion SLA. Auto Loader is designed for incremental new-file discovery with persisted state. The investigation distinguishes the mechanism from an unrelated operational symptom.
Incorrect Answers
A:Inspect write modes and table-history operations around the loss. This diagnose action addresses a different case (append-only delta bronze), where a nightly overwrite accidentally removes historical audit events. Append-only ingestion keeps previous raw records while adding new batches. In the stated problem, listing the full historical directory every run exceeds the ingestion SLA; this choice would not establish the required auto loader file discovery decision.
B:Inspect duplicate file IDs and the ingestion checkpoint state. This diagnose action addresses a different case (retry-safe file loads), where a partially processed input file is loaded twice into Delta. Checkpointed incremental ingestion or stable event-level deduplication prevents repeated effects. In the stated problem, listing the full historical directory every run exceeds the ingestion SLA; this choice would not establish the required auto loader file discovery decision.
C:Inspect representative raw lines and parser quote/escape settings. This diagnose action addresses a different case (malformed csv quotes), where an ingestion reader splits quoted names into extra columns. CSV quoting and escape configurations must match the source serialization. In the stated problem, listing the full historical directory every run exceeds the ingestion SLA; this choice would not establish the required auto loader file discovery decision.
Question 297
At Westridge Research, an ETL repo only has end-to-end tests that require a live warehouse. Architecture constraint: Small logic regressions are discovered late and costly to debug. Which design best addresses this requirement?
- Separate fast local DataFrame unit tests from targeted integration suites
- Add representative expected DataFrame fixtures and schema assertions
- Separate reusable Python modules from resource YAML and target-specific settings
- Refactor business rules as pure DataFrame transform functions
Explanation
Correct Answer
A:Separate fast local DataFrame unit tests from targeted integration suites. This design addresses small logic regressions are discovered late and costly to debug. Unit tests isolate transformations while integration tests validate external contracts. It establishes the right contract or architecture before execution changes.
Incorrect Answers
B:Add representative expected DataFrame fixtures and schema assertions. This design action addresses a different case (dataframe testing), where tests only assert that the DataFrame is nonempty. DataFrame equality and schema assertions test data behavior and contracts. In the stated problem, small logic regressions are discovered late and costly to debug; this choice would not establish the required unit versus integration tests decision.
C:Separate reusable Python modules from resource YAML and target-specific settings. This design action addresses a different case (bundle repository layout), where source files and deployment definitions are coupled to one developer workspace. A versioned Declarative Automation Bundle defines code and resource configurations separately from the target workspace. In the stated problem, small logic regressions are discovered late and costly to debug; this choice would not establish the required unit versus integration tests decision.
D:Refactor business rules as pure DataFrame transform functions. This design action addresses a different case (transform composability), where business logic depends on notebook state and widgets. DataFrame.transform supports composable DataFrame-to-DataFrame functions. In the stated problem, small logic regressions are discovered late and costly to debug; this choice would not establish the required unit versus integration tests decision.
Question 298
At Cobalt Biotech, a bronze layer ingests immutable audit event files. Observed issue: A nightly overwrite accidentally removes historical audit events. Before applying a fix, which investigation is most directly relevant?
- Inspect raw source and the rescued-data column distribution
- Inspect write modes and table-history operations around the loss
- Inspect duplicate file IDs and the ingestion checkpoint state
- Inspect file-discovery backlog and the source format configuration
Explanation
Correct Answer
B:Inspect write modes and table-history operations around the loss. This checks the specific evidence behind a nightly overwrite accidentally removes historical audit events. Append-only ingestion keeps previous raw records while adding new batches. The investigation distinguishes the mechanism from an unrelated operational symptom.
Incorrect Answers
A:Inspect raw source and the rescued-data column distribution. This diagnose action addresses a different case (auto loader rescued data), where unknown or mismatched fields disappear during the bronze load. The rescued data column can preserve records with unexpected schema content for later remediation. In the stated problem, a nightly overwrite accidentally removes historical audit events; this choice would not establish the required append-only delta bronze decision.
C:Inspect duplicate file IDs and the ingestion checkpoint state. This diagnose action addresses a different case (retry-safe file loads), where a partially processed input file is loaded twice into Delta. Checkpointed incremental ingestion or stable event-level deduplication prevents repeated effects. In the stated problem, a nightly overwrite accidentally removes historical audit events; this choice would not establish the required append-only delta bronze decision.
D:Inspect file-discovery backlog and the source format configuration. This diagnose action addresses a different case (auto loader file discovery), where listing the full historical directory every run exceeds the ingestion SLA. Auto Loader is designed for incremental new-file discovery with persisted state. In the stated problem, a nightly overwrite accidentally removes historical audit events; this choice would not establish the required append-only delta bronze decision.
Question 299
A data engineer at Westridge Research must troubleshoot this case: many Unity Catalog managed tables require routine maintenance. Evidence: Operators run blanket manual OPTIMIZE jobs regardless of table use. What should be inspected first to confirm the failure mechanism?
- Inspect compute capabilities and supported physical plan operators
- Inspect per-task shuffle read bytes and spilled data
- Inspect managed table eligibility and current optimization settings
- Inspect current table features, delete patterns and runtime compatibility
Explanation
Correct Answer
C:Inspect managed table eligibility and current optimization settings. This checks the specific evidence behind operators run blanket manual OPTIMIZE jobs regardless of table use. Predictive optimization can automate supported managed-table maintenance based on workload signals. The investigation distinguishes the mechanism from an unrelated operational symptom.
Incorrect Answers
A:Inspect compute capabilities and supported physical plan operators. This diagnose action addresses a different case (photon query execution), where an unsupported execution mode limits vectorized engine use. Photon can accelerate supported SQL and DataFrame operators on compatible compute. In the stated problem, operators run blanket manual OPTIMIZE jobs regardless of table use; this choice would not establish the required predictive optimization decision.
B:Inspect per-task shuffle read bytes and spilled data. This diagnose action addresses a different case (shuffle partition count), where the current partition count is too low for data volume. Shuffle partition sizing affects memory pressure and task parallelism. In the stated problem, operators run blanket manual OPTIMIZE jobs regardless of table use; this choice would not establish the required predictive optimization decision.
D:Inspect current table features, delete patterns and runtime compatibility. This diagnose action addresses a different case (deletion vectors), where each small delete rewrites large data files and increases write cost. Deletion vectors can mark deleted rows without immediate whole-file rewrite when supported. In the stated problem, operators run blanket manual OPTIMIZE jobs regardless of table use; this choice would not establish the required predictive optimization decision.
Question 300
At Northfield Analytics, a SQL workload spends substantial CPU executing supported relational operators. The known risk is: An unsupported execution mode limits vectorized engine use. After remediation, which ongoing signal best detects recurrence?
- Monitor cache hit rate and eviction pressure
- Monitor serverless task failures and cost per run
- Monitor query scans and available column stats
- Monitor query duration and Photon operator usage
Explanation
Correct Answer
D:Monitor query duration and Photon operator usage. This watches the failure mode described by an unsupported execution mode limits vectorized engine use. Photon can accelerate supported SQL and DataFrame operators on compatible compute. It supplies a regression signal after remediation.
Incorrect Answers
A:Monitor cache hit rate and eviction pressure. This monitor action addresses a different case (cache reuse), where repeated recomputation dominates each branch's execution. Persistence can avoid repeated work if reused data fits the memory budget. In the stated problem, an unsupported execution mode limits vectorized engine use; this choice would not establish the required photon query execution decision.
B:Monitor serverless task failures and cost per run. This monitor action addresses a different case (serverless job fit), where provisioning overhead exceeds useful task execution time. Supported serverless jobs can reduce infrastructure management and startup overhead. In the stated problem, an unsupported execution mode limits vectorized engine use; this choice would not establish the required photon query execution decision.
C:Monitor query scans and available column stats. This monitor action addresses a different case (data skipping statistics), where file-level statistics are missing for the filter column. Delta data skipping uses collected column statistics to eliminate files. In the stated problem, an unsupported execution mode limits vectorized engine use; this choice would not establish the required photon query execution decision.