- A
Use BigQuery ML to train a model that identifies anomalies.
Why wrong: ML models are not designed for exact deduplication and add unnecessary complexity.
- B
Use a DML MERGE statement that filters out duplicates based on a unique key.
MERGE with deduplication logic ensures only one copy of each record is inserted, maintaining data quality.
- C
Use Cloud Data Loss Prevention API to scan for duplicates.
Why wrong: DLP is for sensitive data detection, not deduplication.
- D
Use COUNT DISTINCT in queries to ignore duplicates.
Why wrong: This masks duplicates but does not prevent them from being stored; it does not ensure data quality at rest.
Question 934 of 1,000
PDE Ensuring solution quality Practice Question
This PDE practice question tests your understanding of ensuring solution quality. 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.
A company uses BigQuery for analytics. They need to ensure data quality by preventing duplicate records from being inserted. Which approach is most effective?
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 a DML MERGE statement that filters out duplicates based on a unique key.
Option B is correct because BigQuery's DML MERGE statement can be used to atomically insert rows only when a unique key does not already exist in the target table. By using a MERGE with a WHEN NOT MATCHED THEN INSERT clause, the operation prevents duplicate records from being inserted in a single, transactional statement, ensuring data quality without requiring external tools or post-processing.
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.
- ✗
Use BigQuery ML to train a model that identifies anomalies.
Why it's wrong here
ML models are not designed for exact deduplication and add unnecessary complexity.
- ✓
Use a DML MERGE statement that filters out duplicates based on a unique key.
Why this is correct
MERGE with deduplication logic ensures only one copy of each record is inserted, maintaining data quality.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use Cloud Data Loss Prevention API to scan for duplicates.
Why it's wrong here
DLP is for sensitive data detection, not deduplication.
- ✗
Use COUNT DISTINCT in queries to ignore duplicates.
Why it's wrong here
This masks duplicates but does not prevent them from being stored; it does not ensure data quality at rest.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud certifications often test the misconception that data quality tools like DLP or ML can solve structural data integrity problems, when in fact the correct approach is to use native DML operations (like MERGE) that enforce uniqueness at write time.
Detailed technical explanation
How to think about this question
Under the hood, BigQuery's MERGE statement uses a join between the source and target tables on the specified unique key columns. If a match is found, the row is considered a duplicate and can be skipped or updated; if no match is found, the row is inserted. This operation is atomic and fully consistent within BigQuery's distributed architecture, making it a reliable pattern for incremental data loading. A real-world scenario is a daily batch job that ingests event logs; using MERGE with a composite key (e.g., event_id + timestamp) ensures that reprocessing a failed batch does not introduce duplicate rows.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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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FAQ
Questions learners often ask
What does this PDE question test?
Ensuring solution quality — This question tests Ensuring solution quality — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use a DML MERGE statement that filters out duplicates based on a unique key. — Option B is correct because BigQuery's DML MERGE statement can be used to atomically insert rows only when a unique key does not already exist in the target table. By using a MERGE with a WHEN NOT MATCHED THEN INSERT clause, the operation prevents duplicate records from being inserted in a single, transactional statement, ensuring data quality without requiring external tools or post-processing.
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.
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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