Google Associate Cloud Engineer Question 241
Select 4Google Cloud PlatformAs a Google Cloud Engineer, you are tasked with executing queries on a dataset stored in BigQuery to generate a report for your company's sales department. You need to ensure that the query execution costs are kept low. Which of the following actions can help you optimize query performance and cost in BigQuery?
- A
Use SELECT * to retrieve all columns whenever possible.
- B
Filter data using WHERE clauses to limit the amount of data processed.
- C
Use partitioned tables to reduce the amount of data scanned.
- D
Use ORDER BY on fields only when necessary.
- E
Enable caching to reuse previous query results whenever possible.
Show answer and explanation
Correct answers: B, C, D, E
Explanation
To optimize query performance and cost in BigQuery, it's important to limit the amount of data processed. This can be done by using WHERE clauses to filter data, leveraging partitioned tables to scan only relevant partitions, and using ORDER BY judiciously. Enabling caching can also reduce costs by reusing results from previous queries. Avoid using SELECT * as it processes more data than necessary.
- A. Incorrect.
Using SELECT * retrieves all columns, which can unnecessarily increase the amount of data processed and therefore increase costs.
- B. Correct.
Filtering data using WHERE clauses limits the amount of data processed, thus optimizing query performance and cost.
- C. Correct.
Using partitioned tables helps in reducing the amount of data scanned by querying only relevant partitions.
- D. Correct.
Using ORDER BY can increase query costs if not necessary, so it should be used judiciously.
- E. Correct.
Enabling caching helps in reusing previous query results, reducing the need to process the data again and saving costs.