When this query is executed, what will happen with new records that have the same event_id as an existing record?

A junior data engineer on your team has implemented the following code block.

The view new_events contains a batch of records with the same schema as the events Delta table.

The event_id field serves as a unique key for this table.

When this query is executed, what will happen with new records that have the same event_id as an existing record?
A . They are merged.
B . They are ignored.
C . They are updated.
D . They are inserted.
E . They are deleted.

Answer: B

Explanation:

This is the correct answer because it describes what will happen with new records that have the same event_id as an existing record when the query is executed. The query uses the INSERT INTO command to append new records from the view new_events to the table events. However, the INSERT INTO command does not check for duplicate values in the primary key column (event_id) and does not perform any update or delete operations on existing records. Therefore, if there are new records that have the same event_id as an existing record, they will be ignored and not inserted into the table events.

Verified Reference: [Databricks Certified Data Engineer Professional], under “Delta Lake” section; Databricks Documentation, under “Append data using INSERT INTO” section.

"If none of the WHEN MATCHED conditions evaluate to true for a source and target row pair that matches the merge_condition, then the target row is left unchanged." https://docs.databricks.com/en/sql/language-manual/delta-merge-into.html#:~:text=If%20none%20of%20the%20WHEN%20MATCHED%20conditions%20evaluate%20t o%20true%20for%20a%20source%20and%20target%20row%20pair%20that%20matches%20the%20 merge_condition%2C%20then%20the%20target%20row%20is%20left%20unchanged.