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Exam Certified Data Engineer Professional topic 1 question 96 discussion

Actual exam question from Databricks's Certified Data Engineer Professional
Question #: 96
Topic #: 1
[All Certified Data Engineer Professional Questions]

A junior data engineer is migrating a workload from a relational database system to the Databricks Lakehouse. The source system uses a star schema, leveraging foreign key constraints and multi-table inserts to validate records on write.

Which consideration will impact the decisions made by the engineer while migrating this workload?

  • A. Databricks only allows foreign key constraints on hashed identifiers, which avoid collisions in highly-parallel writes.
  • B. Databricks supports Spark SQL and JDBC; all logic can be directly migrated from the source system without refactoring.
  • C. Committing to multiple tables simultaneously requires taking out multiple table locks and can lead to a state of deadlock.
  • D. All Delta Lake transactions are ACID compliant against a single table, and Databricks does not enforce foreign key constraints.
  • E. Foreign keys must reference a primary key field; multi-table inserts must leverage Delta Lake’s upsert functionality.
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Suggested Answer: D 🗳️
by 60ties at Nov. 15, 2023, 1:41 p.m.

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vctrhugo
Highly Voted 9 months ago
Selected Answer: D
In Databricks Delta Lake, transactions are ACID compliant at the table level, meaning that transactions apply to a single table. However, Delta Lake does not enforce foreign key constraints across tables. Therefore, the data engineer needs to be aware that Databricks does not automatically enforce referential integrity between tables through foreign key constraints, and it becomes the responsibility of the data engineer to manage these relationships appropriately.
upvoted 6 times
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alexvno
Most Recent 10 months, 2 weeks ago
Selected Answer: D
Primary and foreign keys are informational only and are not enforced.
upvoted 2 times
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60ties
11 months, 3 weeks ago
Selected Answer: D
D makes more sense. Since there are no database-level transactions, locks, or guarantees, and since primary key & foreign key constraints are informational only, there is no guarantee of enforced relations (the start schema) in place will remain in place after migration. This means B cannot be right.
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