Exam Certified Data Engineer Professional topic 1 question 121 discussion

Actual exam question from Databricks's Certified Data Engineer Professional

Question #: 121
Topic #: 1

[All Certified Data Engineer Professional Questions]

A Databricks SQL dashboard has been configured to monitor the total number of records present in a collection of Delta Lake tables using the following query pattern:

SELECT COUNT (*) FROM table -

Which of the following describes how results are generated each time the dashboard is updated?

A. The total count of rows is calculated by scanning all data files
B. The total count of rows will be returned from cached results unless REFRESH is run
C. The total count of records is calculated from the Delta transaction logs
D. The total count of records is calculated from the parquet file metadata

Show Suggested Answer

Suggested Answer: C 🗳️

by MDWPartners at May 30, 2024, 9:13 a.m.

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KadELbied

1 month ago

Selected Answer: C

Suretly C

upvoted 1 times

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AlejandroU

5 months, 3 weeks ago

Answer is D. This is same question #63. Delta Lake stores its data in Parquet format. Parquet files include metadata (like row counts) that can be efficiently queried. For a COUNT(*) query, Delta Lake does not need to scan all the data files; instead, it reads the row count information stored in the Parquet file metadata, making the operation faster.

upvoted 1 times

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vexor3

11 months ago

Selected Answer: C

C is correct

upvoted 1 times

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hpkr

1 year ago

Selected Answer: C

C is correct

upvoted 1 times

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BrianNguyen95

1 year ago

Selected Answer: C

Delta Lake optimizes COUNT(*) queries by reading the row counts stored in the Delta transaction log. This eliminates the need for a full table scan, resulting in significantly faster query performance. pen_spark

upvoted 1 times

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Freyr

1 year ago

Selected Answer: C

Correct Answer: C

upvoted 1 times

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MDWPartners

1 year ago

Selected Answer: C

I would've said C

upvoted 2 times

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