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Google Professional Data Engineer Exam Actual Questions

The questions for Professional Data Engineer were last updated at Jan. 25, 2020.
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  • Viewing questions 1-4 out of 78 questions

Topic 1 - Single Topic

Question #1 Topic 1

Suppose you have a table that includes a nested column called "city" inside a column called "person", but when you try to submit the following query in BigQuery, it gives you an error.
SELECT person FROM `project1.example.table1` WHERE city = "London"
How would you correct the error?

  • A. Add ", UNNEST(person)" before the WHERE clause.
  • B. Change "person" to "person.city".
  • C. Change "person" to "city.person".
  • D. Add ", UNNEST(city)" before the WHERE clause.
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Correct Answer: A
To access the person.city column, you need to "UNNEST(person)" and JOIN it to table1 using a comma.
Reference: https://cloud.google.com/bigquery/docs/reference/standard-sql/migrating-from-legacy-sql#nested_repeated_results

Question #2 Topic 1

What are two of the benefits of using denormalized data structures in BigQuery?

  • A. Reduces the amount of data processed, reduces the amount of storage required
  • B. Increases query speed, makes queries simpler
  • C. Reduces the amount of storage required, increases query speed
  • D. Reduces the amount of data processed, increases query speed
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Correct Answer: B
Denormalization increases query speed for tables with billions of rows because BigQuery's performance degrades when doing JOINs on large tables, but with a denormalized data structure, you don't have to use JOINs, since all of the data has been combined into one table. Denormalization also makes queries simpler because you do not have to use JOIN clauses.
Denormalization increases the amount of data processed and the amount of storage required because it creates redundant data.
Reference: https://cloud.google.com/solutions/bigquery-data-warehouse#denormalizing_data

Question #3 Topic 1

Which of these statements about exporting data from BigQuery is false?

  • A. To export more than 1 GB of data, you need to put a wildcard in the destination filename.
  • B. The only supported export destination is Google Cloud Storage.
  • C. Data can only be exported in JSON or Avro format.
  • D. The only compression option available is GZIP.
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Correct Answer: C
Data can be exported in CSV, JSON, or Avro format. If you are exporting nested or repeated data, then CSV format is not supported.
Reference: https://cloud.google.com/bigquery/docs/exporting-data

Question #4 Topic 1

What are all of the BigQuery operations that Google charges for?

  • A. Storage, queries, and streaming inserts
  • B. Storage, queries, and loading data from a file
  • C. Storage, queries, and exporting data
  • D. Queries and streaming inserts
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Correct Answer: A
Google charges for storage, queries, and streaming inserts. Loading data from a file and exporting data are free operations.
Reference: https://cloud.google.com/bigquery/pricing