Databricks Updated Databricks-Certified-Data-Engineer-Associate Exam Questions and Answers by cruze

Databricks describes the Bronze layer in the Medallion Architecture as the raw ingestion layer , where source data is landed with minimal validation or transformation so that the original records are preserved for auditability and reprocessing. This is especially important for sources like Kafka clickstream events and file-based product catalogs, because downstream logic such as cleansing, deduplication, conformance, and business modeling should happen later in Silver and Gold layers. Bronze data is commonly stored in an append-only pattern and may include basic ingestion metadata, but it should not be heavily transformed at this stage. Databricks explicitly recommends limiting cleanup and validation in Bronze and using Silver for validation and deduplication. That makes option C the best match to Databricks guidance. Options A, B, and D all skip or misuse the Bronze layer, which reduces traceability and makes recovery or replay harder if business logic changes later.

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JSON data is a text-based format that represents data as a collection of name-value pairs. By default, when Auto Loader infers the schema of JSON data, it treats all columns as strings. This is because JSON data can have varying data types for the same column across different files or records, and Auto Loader does not attempt to reconcile these differences. For example, a column named “age” may have integer values in some files, but string values in others. To avoid data loss or errors, Auto Loader infers the column as a string type. However, Auto Loader also provides an option to infer more precise column types based on the sample data. This option is called cloudFiles.inferColumnTypes and it can be set to true or false. When set to true, Auto Loader tries to infer the exact data types of the columns, such as integers, floats, booleans, or nested structures. When set to false, Auto Loader infers all columns as strings. The default value of this option is false. References: Configure schema inference and evolution in Auto Loader, Schema inference with auto loader (non-DLT and DLT), Using and Abusing Auto Loader’s Inferred Schema, Explicit path to data or a defined schema required for Auto loader.

The Auto Stop feature allows the SQL endpoint to automatically stop after a specified period of inactivity. This can help reduce the cost and resource consumption of the SQL endpoint, as it will only run when it is needed to refresh the dashboard or execute queries. The data engineer can configure the Auto Stop setting for the SQL endpoint from the SQL Endpoints UI, by selecting the desired idle time from the Auto Stop dropdown menu. The default idle time is 120 minutes, but it can be set to as low as 15 minutes or as high as 240 minutes. Alternatively, the data engineer can also use the SQL Endpoints REST API to set the Auto Stop setting programmatically. References: SQL Endpoints UI, SQL Endpoints REST API, Refreshing SQL Dashboard

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.