Google Exam Professional Data Engineer Topic 4 Question 64 Discussion

Actual exam question for Google's Professional Data Engineer exam

Question #: 64
Topic #: 4

[All Professional Data Engineer Questions]

You are using Google BigQuery as your data warehouse. Your users report that the following simple query is running very slowly, no matter when they run the query:

SELECT country, state, city FROM [myproject:mydataset.mytable] GROUP BY country

You check the query plan for the query and see the following output in the Read section of Stage:1:

What is the most likely cause of the delay for this query?

AUsers are running too many concurrent queries in the system

BThe [myproject:mydataset.mytable] table has too many partitions

CEither the state or the city columns in the [myproject:mydataset.mytable] table have too many
NULL values

DMost rows in the [myproject:mydataset.mytable] table have the same value in the country column, causing data skew

Show Suggested Answer

Suggested Answer: C

by Dalene at Jan 09, 2023, 01:26 PM

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Amina

14 days ago

Who needs speed when you can just sit back and enjoy the slow, steady progress of your query? It's like watching grass grow, but with numbers!

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Tammara

16 days ago

I'm pretty sure the users are just running too many queries at the same time. They need to schedule their queries better!

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Haydee

25 days ago

Hmm, I bet the data is skewed in the country column. Too many rows with the same value would explain the slow performance.

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Rene

4 days ago

A) Users are running too many concurrent queries in the system

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2 months ago

The query is slow because there are too many partitions in the table. The data is not distributed evenly, causing the system to work harder to process all the partitions.

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