Databricks Certified Data Engineer - Associate

Explanation

When creating a new Delta Live Tables pipeline, the only mandatory requirement is to specify at least one notebook library to be executed. This is because Delta Live Tables pipelines are defined through code (notebooks or Python files) that contain the data transformation logic.

Let's examine why the other options are not required:

A. A key-value pair configuration - Configuration settings are optional and can be used to customize pipeline behavior, but they are not mandatory.

B. The preferred DBU/hour cost - Cost settings are optional and can be configured for cost optimization, but they are not required for pipeline creation.

C. A path to cloud storage location for the written data - Storage location is optional. Delta Live Tables can use default storage locations if not explicitly specified.

D. A location of a target database for the written data - Database location is optional. Tables can be created in the default database if not specified.

E. At least one notebook library to be executed - CORRECT. This is mandatory because the pipeline needs source code (notebooks or Python files) that define the data transformations and tables.

According to the Databricks documentation, storage and location configurations are optional, but you must specify at least one notebook or Python file that contains the pipeline code.