- A
Check the BigQuery jobs list for similar queries.
Why wrong: The jobs list shows past costs but not an estimate for a new query.
- B
Use the BigQuery cache to estimate if the query is cached.
Why wrong: Caching doesn't provide cost estimation; it avoids charges for rerun queries.
- C
Run EXPLAIN on the query to see the query plan.
Why wrong: EXPLAIN shows the execution plan but not the cost estimate.
- D
Use the bq command with the --dry_run flag.
Dry run estimates the bytes processed, allowing cost estimation without running the query.
Question 25 of 1,000
PDE Maintaining and Automating Data Workloads Practice Question
This PDE practice question tests your understanding of maintaining and automating data workloads. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You need to estimate the cost of a BigQuery query before running it. Which command or feature should you use?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"which command"Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use the bq command with the --dry_run flag.
Option D is correct because the `bq` command with the `--dry_run` flag allows you to estimate the amount of data a BigQuery query will process before actually executing it. This dry run does not read any data or incur charges; it simply returns the estimated bytes to be processed, which you can use to calculate the cost based on BigQuery's pricing model.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Check the BigQuery jobs list for similar queries.
Why it's wrong here
The jobs list shows past costs but not an estimate for a new query.
- ✗
Use the BigQuery cache to estimate if the query is cached.
Why it's wrong here
Caching doesn't provide cost estimation; it avoids charges for rerun queries.
- ✗
Run EXPLAIN on the query to see the query plan.
Why it's wrong here
EXPLAIN shows the execution plan but not the cost estimate.
- ✓
Use the bq command with the --dry_run flag.
Why this is correct
Dry run estimates the bytes processed, allowing cost estimation without running the query.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common trap is confusing the EXPLAIN command (which shows the query plan) with the `--dry_run` flag (which estimates bytes processed and cost).
Trap categories for this question
Command / output trap
The jobs list shows past costs but not an estimate for a new query.
Detailed technical explanation
How to think about this question
The `--dry_run` flag works by submitting the query to BigQuery's query planner, which parses the SQL, resolves table and column references, and computes the total number of bytes that would be read from storage. This estimate is based on the table's metadata (e.g., partition boundaries, clustering information) and is returned without executing the query, making it a zero-cost operation. In real-world scenarios, this is critical for cost governance, especially when dealing with large partitioned tables where a poorly written query could scan terabytes of data.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Maintaining and Automating Data Workloads — study guide chapter
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FAQ
Questions learners often ask
What does this PDE question test?
Maintaining and Automating Data Workloads — This question tests Maintaining and Automating Data Workloads — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use the bq command with the --dry_run flag. — Option D is correct because the `bq` command with the `--dry_run` flag allows you to estimate the amount of data a BigQuery query will process before actually executing it. This dry run does not read any data or incur charges; it simply returns the estimated bytes to be processed, which you can use to calculate the cost based on BigQuery's pricing model.
What should I do if I get this PDE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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