Question 36 of 1,446
Design innovative, scalable, and highly available cloud database solutions →mediumMultiple ChoiceObjective-mapped
PCDE Practice Question: Design innovative, scalable, and highly available cloud database solutions
A data engineer is designing a schema for Cloud Spanner to store a hierarchy of customers and their orders. Customers have many orders, and queries often retrieve orders for a specific customer. To optimize performance and reduce cross-node reads, which schema design pattern should the engineer use?
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 parent-child interleaved table structure where Orders are interleaved in Customers.
Spanner's interleaved tables allow storing child rows (orders) physically co-located with their parent row (customer) using the same primary key prefix. This enables efficient joins and reduces cross-node reads. A secondary index with STORING is useful for other access patterns but not for hierarchical queries. Denormalization is not recommended in Spanner.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Denormalize by embedding order details as a repeated field within the customer row.
Why it's wrong here
Spanner does not support repeated fields; denormalization is not recommended.
- ✓
Use a parent-child interleaved table structure where Orders are interleaved in Customers.
Why this is correct
Interleaving co-locates data, improving performance for hierarchical queries.
- ✗
Normalize customers and orders into separate tables without any relationship.
Why it's wrong here
Without interleaving, queries may require cross-node joins and are inefficient.
- ✗
Create a secondary index with STORING on the order ID.
Why it's wrong here
A secondary index does not co-locate data; it only speeds up lookups by order ID.
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Last reviewed: Jul 4, 2026
This PCDE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCDE exam.
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