Exam Certified Data Engineer Professional topic 1 question 78 discussion

Actual exam question from Databricks's Certified Data Engineer Professional

Question #: 78
Topic #: 1

[All Certified Data Engineer Professional Questions]

The data engineering team maintains the following code:

Assuming that this code produces logically correct results and the data in the source table has been de-duplicated and validated, which statement describes what will occur when this code is executed?

A. The silver_customer_sales table will be overwritten by aggregated values calculated from all records in the gold_customer_lifetime_sales_summary table as a batch job.
B. A batch job will update the gold_customer_lifetime_sales_summary table, replacing only those rows that have different values than the current version of the table, using customer_id as the primary key.
C. The gold_customer_lifetime_sales_summary table will be overwritten by aggregated values calculated from all records in the silver_customer_sales table as a batch job.
D. An incremental job will leverage running information in the state store to update aggregate values in the gold_customer_lifetime_sales_summary table.
E. An incremental job will detect if new rows have been written to the silver_customer_sales table; if new rows are detected, all aggregates will be recalculated and used to overwrite the gold_customer_lifetime_sales_summary table.

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Suggested Answer: C 🗳️

by sturcu at Oct. 25, 2023, 7:36 a.m.

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aragorn_brego

Highly Voted 1 year ago

Selected Answer: C

The code is performing a batch aggregation operation on the "silver_customer_sales" table grouped by "customer_id". It calculates the first and last transaction dates, the average sales, the total number of distinct orders, and the lifetime value of sales for each customer. The .mode("overwrite") operation specifies that the output table "gold_customer_lifetime_sales_summary" should be overwritten with the result of this aggregation. This means that every time this code runs, it will replace the existing "gold_customer_lifetime_sales_summary" table with a new version that reflects the current state of the "silver_customer_sales" table.

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