Certified Data Engineer Professional Exam

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Question 127

The following table consists of items found in user carts within an e-commerce website.

The following MERGE statement is used to update this table using an updates view, with schema evolution enabled on this table.

How would the following update be handled?

The update throws an error because changes to existing columns in the target schema are not supported.

The new nested Field is added to the target schema, and dynamically read as NULL for existing unmatched records.

The update is moved to a separate "rescued" column because it is missing a column expected in the target schema.

The new nested field is added to the target schema, and files underlying existing records are updated to include NULL values for the new field.

Correct Answer: D

The new nested field 'coupon' is added to the target schema as schema evolution is enabled. Therefore, the underlying files for existing records would be updated to include NULL values for the new field 'coupon' where it is not present. This matches the described behavior of schema evolution, where the schema adapts to include new fields and updates records accordingly.

Discussion

MDWPartnersOption: B

schema evolution is enabled, so B.

FreyrOption: B

Correct Answer: B. In the question it is mentioned that the schema evolution is enabled. This option states that the new nested field is added to the target schema, and existing records not matching the new schema format are populated with NULL for the newly added columns. This behavior aligns with how schema evolution functions in Delta Lake, dynamically adapting the schema to include new fields.