Databricks-Certified-Data-Engineer-Associate Exam Dumps : Databricks Certified Data Engineer Associate Exam

DataFrame.dropna() removes rows containing NULL or NaN values. Its default how= " any " behavior removes a row when any column included in the specified subset is NULL. By passing [ " customer_email " , " customer_phone " ] as the subset, the operation removes a record when either required field is missing, while ignoring NULL values in unrelated columns. Option B can produce the same filtering result, but it uses two chained where() calls and therefore does not meet the single-method-call requirement. Option C uses how= " all " and would remove a row only when all evaluated columns are NULL. Option D contains one filter() operation but requires multiple column-function calls. Consequently, option A is the direct PySpark method designed for this requirement.

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For small-scale, ad hoc Python workloads that run frequently and should start quickly and stop without leaving idle infrastructure running, serverless compute is the best fit. Databricks documentation explains that serverless compute allows users to run workloads without provisioning compute resources manually , and Databricks automatically allocates and manages the required resources. This improves startup and scaling speed and minimizes idle time, which directly matches the requirement that compute should “wind down quickly” after the work completes. Databricks also recommends serverless compute broadly when the workload is supported because it is the simplest and most reliable option. An all-purpose cluster is better suited to interactive collaborative development and can remain running longer than needed. A job cluster is ephemeral and often a good batch choice, but it still requires more explicit configuration than serverless and is not as optimized for minimal operational overhead. A SQL warehouse is intended for SQL workloads, not general ad hoc Python script execution. Therefore, serverless compute is the most appropriate choice.

The reason why all of the data files and metadata files were deleted from the file system after dropping the table is that the table was managed. A managed table is a table that is created and managed by Spark SQL. It stores both the data and the metadata in the default location specified by the spark.sql.warehouse.dir configuration property. When a managed table is dropped, both the data and the metadata are deleted from the file system.

Option B is not correct, as the size of the table’s data does not affect the behavior of dropping the table. Whether the table’s data is smaller or larger than 10 GB, the data files and metadata files will be deleted if the table is managed, and will be preserved if the table is external.

Option C is not correct, for the same reason as option B.

Option D is not correct, as an external table is a table that is created and managed by the user. It stores the data in a user-specified location, and only stores the metadata in the Spark SQL catalog. When an external table is dropped, only the metadata is deleted from the catalog, but the data files are preserved in the file system.

Option E is not correct, as a table must have a location to store the data. If the location is not specified by the user, it will use the default location for managed tables. Therefore, a table without a location is a managed table, and dropping it will delete both the data and the metadata.

Managing Tables

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