PCDE Practice Question: Define data structures and implement SQL for Business Intelligence
This PCDE practice question tests your understanding of define data structures and implement sql for business intelligence. 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.
Exhibit
Refer to the exhibit. In a BigQuery query plan, you see the following stage statistics:
Stage 2: WRITE, 1.2 GB shuffled, 45 seconds
Stage 3: SHUFFLE, 2.5 GB shuffled, 80 seconds
Stage 4: AGGREGATE, 0.5 GB input, 15 seconds
Refer to the exhibit. The query joins two large tables and aggregates results. Which optimization would most likely reduce the high shuffle bytes in Stage 3?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Refer to the exhibit. In a BigQuery query plan, you see the following stage statistics:
Stage 2: WRITE, 1.2 GB shuffled, 45 seconds
Stage 3: SHUFFLE, 2.5 GB shuffled, 80 seconds
Stage 4: AGGREGATE, 0.5 GB input, 15 seconds
A
Add a WHERE clause to filter rows before the join.
Filtering early reduces the data that needs to be shuffled.
B
Ensure both tables are clustered on the join key.
Why wrong: Clustering can reduce shuffle but not as much as filtering.
C
Use a broadcast join hint to force one table to be broadcast.
Why wrong: Broadcast joins only help if one table is small.
D
Add an ORDER BY clause to sort the data before aggregation.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a WHERE clause to filter rows before the join.
Option A is correct because filtering data before the join reduces the amount of data shuffled. Option B is wrong because clustering on the join key reduces the shuffle but may not eliminate it. Option C is wrong because the join itself causes data movement; using a manual broadcast join might help only if one table is small, but it is not automatic. Option D is wrong because ORDER BY is not the main cause of the shuffle; the join is.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Add a WHERE clause to filter rows before the join.
Why this is correct
Filtering early reduces the data that needs to be shuffled.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Clustering can reduce shuffle but not as much as filtering.
✗
Use a broadcast join hint to force one table to be broadcast.
Why it's wrong here
Broadcast joins only help if one table is small.
✗
Add an ORDER BY clause to sort the data before aggregation.
Why it's wrong here
ORDER BY would increase shuffle.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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. Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets. 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.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCDE subnetting questions on CIDR, address ranges, and subnet selection.
Define data structures and implement SQL for Business Intelligence — This question tests Define data structures and implement SQL for Business Intelligence — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Add a WHERE clause to filter rows before the join. — Option A is correct because filtering data before the join reduces the amount of data shuffled. Option B is wrong because clustering on the join key reduces the shuffle but may not eliminate it. Option C is wrong because the join itself causes data movement; using a manual broadcast join might help only if one table is small, but it is not automatic. Option D is wrong because ORDER BY is not the main cause of the shuffle; the join is.
What should I do if I get this PCDE question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCDE subnetting questions on CIDR, address ranges, and subnet selection.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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