Which of the following commands will return the number of null values in the member_id column?

1. A. SELECT count(member_id) FROM my_table;
2. B. SELECT count(member_id) - count_null(member_id) FROM my_table;
3. C. SELECT count_if(member_id IS NULL) FROM my_table;
4. D. SELECT null(member_id) FROM my_table;
5. E. SELECT count_null(member_id) FROM my_table;

Correct Answer: C
https://docs.databricks.com/en/sql/language-manual/functions/count.html
Returns
A BIGINT.
If * is specified also counts row containing NULL values.
If expr are specified counts only rows for which all expr are not NULL. If DISTINCT duplicate rows are not counted.

Which of the following is hosted completely in the control plane of the classic Databricks architecture?

1. A. Worker node
2. B. JDBC data source
3. C. Databricks web application
4. D. Databricks Filesystem
5. E. Driver node

Correct Answer: C
In the classic Databricks architecture, the control plane includes components like the Databricks web application, the Databricks REST API, and the Databricks Workspace. These components are responsible for managing and controlling the Databricks environment, including cluster provisioning, notebook management, access control, and job scheduling. The other options, such as worker nodes, JDBC data sources, Databricks Filesystem (DBFS), and driver nodes, are typically part of the data plane or the execution environment, which is separate from the control plane. Worker nodes are responsible for executing tasks and computations, JDBC data sources are used to connect to external databases, DBFS is a distributed file system for data storage, and driver nodes are responsible for coordinating the execution of Spark jobs.

A data engineer has a single-task Job that runs each morning before they begin working. After identifying an upstream data issue, they need to set up another task to run a new notebook prior to the original task.
Which of the following approaches can the data engineer use to set up the new task?

1. A. They can clone the existing task in the existing Job and update it to run the new notebook.
2. B. They can create a new task in the existing Job and then add it as a dependency of the original task.
3. C. They can create a new task in the existing Job and then add the original task as a dependency of the new task.
4. D. They can create a new job from scratch and add both tasks to run concurrently.
5. E. They can clone the existing task to a new Job and then edit it to run the new notebook.

Correct Answer: B
To set up the new task to run a new notebook prior to the original task in a single-task Job, the data engineer can use the following approach: In the existing Job, create a new task that corresponds to the new notebook that needs to be run. Set up the new task with the appropriate configuration, specifying the notebook to be executed and any necessary parameters or dependencies. Once the new task is created, designate it as a dependency of the original task in the Job configuration. This ensures that the new task is executed before the original task.

A data engineer wants to schedule their Databricks SQL dashboard to refresh every hour, but they only want the associated SQL endpoint to be running when it is necessary. The dashboard has multiple queries on multiple datasets associated with it. The data that feeds the dashboard is automatically processed using a Databricks Job.
Which of the following approaches can the data engineer use to minimize the total running time of the SQL endpoint used in the refresh schedule of their dashboard?

1. A. They can turn on the Auto Stop feature for the SQL endpoint.
2. B. They can ensure the dashboard's SQL endpoint is not one of the included query's SQL endpoint.
3. C. They can reduce the cluster size of the SQL endpoint.
4. D. They can ensure the dashboard's SQL endpoint matches each of the queries' SQL endpoints.
5. E. They can set up the dashboard's SQL endpoint to be serverless.

Correct Answer: A

Which of the following commands can be used to write data into a Delta table while avoiding the writing of duplicate records?

1. A. DROP
2. B. IGNORE
3. C. MERGE
4. D. APPEND
5. E. INSERT

Correct Answer: C
To write data into a Delta table while avoiding the writing of duplicate records, you can use the MERGE command. The MERGE command in Delta Lake allows you to combine the ability to insert new records and update existing records in a single atomic operation. The MERGE command compares the data being written with the existing data in the Delta table based on specified matching criteria, typically using a primary key or unique identifier. It then performs conditional actions, such as inserting new records or updating existing records, depending on the comparison results. By using the MERGE command, you can handle the prevention of duplicate records in a more controlled and efficient manner. It allows you to synchronize and reconcile data from different sources while avoiding duplication and ensuring data integrity.