Databricks-Certified-Professional-Data-Engineer 無料問題集「Databricks Certified Professional Data Engineer」

（A）Tungsten encoding used by Databricks is optimized for storing string data: newly-added native support for querying JSON strings means that string types are always most efficient.

（B）Because Delta Lake uses Parquet for data storage, Dremel encoding information for nesting can be directly referenced by the Delta transaction log.

（C）By default Delta Lake collects statistics on the first 32 columns in a table; these statistics are leveraged for data skipping when executing selective queries.

（D）Schema inference and evolution on Databricks ensure that inferred types will always accurately match the data types used by downstream systems.

（A）Because the SHA256 hash is used to obfuscate stored secrets, reversing this hash will display the value in plain text.

（B）Iterating through a stored secret and printing each character will display secret contents in plain text.

（C）Account administrators can see all secrets in plain text by logging on to the Databricks Accounts console.

（D）Secrets are stored in an administrators-only table within the Hive Metastore; database administrators have permission to query this table by default.

（E）The Databricks REST API can be used to list secrets in plain text if the personal access token has proper credentials.

（A）Because all tasks are managed as a dependency graph, no changes will be committed to the Lakehouse until all tasks have successfully been completed.

（B）Tasks B and C will be skipped; some logic expressed in task A may have been committed before task failure.

（C）Tasks B and C will attempt to run as configured; any changes made in task A will be rolled back due to task failure.

（D）Tasks B and C will be skipped; task A will not commit any changes because of stage failure.

（E）Unless all tasks complete successfully, no changes will be committed to the Lakehouse; because task A failed, all commits will be rolled back automatically.

（A）In environments where interactive code will be executed, production data should only be accessible with read permissions; creating isolated databases for each environment further reduces risks.

（B）Because delta Lake versions all data and supports time travel, it is not possible for user error or malicious actors to permanently delete production data, as such it is generally safe to mount production data anywhere.

（C）All developer, testing and production code and data should exist in a single unified workspace; creating separate environments for testing and development further reduces risks.

（D）Because access to production data will always be verified using passthrough credentials it is safe to mount data to any Databricks development environment.

（A）Therecent_sensor_recordingstable was unresponsive for three consecutive runs of the query

（B）The average temperature recordings for at least one sensor exceeded 120 on three consecutive executions of the query

（C）The maximum temperature recording for at least one sensor exceeded 120 on three consecutive executions of the query

（D）The total average temperature across all sensors exceeded 120 on three consecutive executions of the query

（E）The source query failed to update properly for three consecutive minutes and then restarted

（A）Df. Select (''customer_id''.
Model (''columns) alias (''predictions'')

（B）Df.apply(model, columns). Select (''customer_id, prediction''

（C）Df, map (lambda k:midel (x [columns]) ,select (''customer_id predictions'')

（D）Model, predict (df, columns)

（A）Execute a query to calculate the difference between the new version and the previous version using Delta Lake's built-in versioning and time travel functionality.

（B）Parse the Spark event logs to identify those rows that were updated, inserted, or deleted.

（C）Parse the Delta Lake transaction log to identify all newly written data files.

（D）Execute DESCRIBE HISTORY customer_churn_params to obtain the full operation metrics for the update, including a log of all records that have been added or modified.

（A）Define a view that performs a left outer join on validation_copy and report, and reference this view in DLT expectations for the report table

（B）Define a SQL UDF that performs a left outer join on two tables, and check if this returns null values for report key values in a DLT expectation for the report table.

（C）Define a function that performs a left outer join on validation_copy and report and report, and check against the result in a DLT expectation for the report table

（D）Define a temporary table that perform a left outer join on validation_copy and report, and define an expectation that no report key values are null

（A）Use merge into to insert, update, or delete the most recent entry for each pk_id into a bronze table, then propagate all changes throughout the system.

（B）Use Delta Lake's change data feed to automatically process CDC data from an external system, propagating all changes to all dependent tables in the Lakehouse.

（C）Create a separate history table for each pk_id resolve the current state of the table by running a union all filtering the history tables for the most recent state.

（D）Iterate through an ordered set of changes to the table, applying each in turn; rely on Delta Lake's versioning ability to create an audit log.

（E）Ingest all log information into a bronze table; use merge into to insert, update, or delete the most recent entry for each pk_id into a silver table to recreate the current table state.

（A）A shuffle occurs prior to writing to try to group data together resulting in fewer files instead of each executor writing multiple files based on directory partitions.

（B）An asynchronous job runs after the write completes to detect if files could be further compacted; yes, an OPTIMIZE job is executed toward a default of 1 GB.

（C）Before a job cluster terminates, OPTIMIZE is executed on all tables modified during the most recent job.

（D）Optimized writes logical partitions instead of directory partitions partition boundaries are only represented in metadata fewer small files are written.