- A
Store orders and line items in separate regions
Why wrong: Separate regions would increase latency and are not recommended for co-location.
- B
Use interleaved tables for orders and line items
Interleaving stores line items with their parent order for faster joins.
- C
Define a primary key on orders as (order_id) and line items as (order_id, line_item_id)
This composite key ensures line items are co-located with their order.
- D
Use local secondary indexes on line items
Local indexes are stored with the parent row, improving query performance.
- E
Use global secondary indexes on line items
Why wrong: Global indexes may require cross-split queries, reducing performance.
Question 667 of 980
Design Scalable and Highly Available Cloud Database Solutions →mediumMultiple SelectObjective-mapped
PCD Practice Question: Design Scalable and Highly Available Cloud Database Solutions
This PCD practice question tests your understanding of design scalable and highly available cloud database solutions. 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 is using Cloud Spanner for a global inventory system. They need to ensure that queries for an order and its line items are fast. Which THREE design choices will help achieve this? (Choose three)
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 interleaved tables for orders and line items
Interleaved tables in Cloud Spanner physically co-locate parent and child rows on the same split, so a query joining orders and line items by the parent key (order_id) can be served from a single split without distributed reads. This eliminates cross-node network hops, dramatically reducing latency for the inventory system's order+line-item queries.
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.
- ✗
Store orders and line items in separate regions
Why it's wrong here
Separate regions would increase latency and are not recommended for co-location.
- ✓
Use interleaved tables for orders and line items
Why this is correct
Interleaving stores line items with their parent order for faster joins.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Define a primary key on orders as (order_id) and line items as (order_id, line_item_id)
Why this is correct
This composite key ensures line items are co-located with their order.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Use local secondary indexes on line items
Why this is correct
Local indexes are stored with the parent row, improving query performance.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use global secondary indexes on line items
Why it's wrong here
Global indexes may require cross-split queries, reducing performance.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that global secondary indexes are always faster than local ones, but in Spanner, local secondary indexes are optimized for parent-child queries because they are co-located with the base table rows, while global indexes may require cross-split lookups.
Detailed technical explanation
How to think about this question
Under the hood, interleaved tables use the parent table's primary key as the prefix for the child table's primary key, ensuring that all rows for a given order_id are stored contiguously on the same tablet. This design leverages Spanner's TrueTime and Paxos-based replication to maintain strong consistency without sacrificing locality. In a real-world global inventory system, this means a query like 'SELECT * FROM Orders WHERE order_id = ? JOIN LineItems USING (order_id)' can be resolved with a single split scan, avoiding the 2–10 ms overhead of distributed query execution.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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.
- →
Design Scalable and Highly Available Cloud Database Solutions — study guide chapter
Learn the concepts, then practise the questions
- →
Design Scalable and Highly Available Cloud Database Solutions practice questions
Targeted practice on this topic area only
- →
All PCD questions
980 questions across all exam domains
- →
Google Professional Cloud Developer study guide
Full concept coverage aligned to exam objectives
- →
PCD practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related PCD practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Manage a Solution that Can Span Multiple Database Systems practice questions
Practise PCD questions linked to Manage a Solution that Can Span Multiple Database Systems.
Deploy Scalable and Highly Available Databases in Google Cloud practice questions
Practise PCD questions linked to Deploy Scalable and Highly Available Databases in Google Cloud.
Design Scalable and Highly Available Cloud Database Solutions practice questions
Practise PCD questions linked to Design Scalable and Highly Available Cloud Database Solutions.
Migrate Data Solutions practice questions
Practise PCD questions linked to Migrate Data Solutions.
Designing highly scalable, available, and reliable cloud-native applications practice questions
Practise PCD questions linked to Designing highly scalable, available, and reliable cloud-native applications.
Building and testing applications practice questions
Practise PCD questions linked to Building and testing applications.
Deploying applications practice questions
Practise PCD questions linked to Deploying applications.
Integrating Google Cloud services practice questions
Practise PCD questions linked to Integrating Google Cloud services.
Managing application performance monitoring practice questions
Practise PCD questions linked to Managing application performance monitoring.
PCD fundamentals practice questions
Practise PCD questions linked to PCD fundamentals.
PCD scenario practice questions
Practise PCD questions linked to PCD scenario.
PCD troubleshooting practice questions
Practise PCD questions linked to PCD troubleshooting.
Practice this exam
Start a free PCD practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this PCD question test?
Design Scalable and Highly Available Cloud Database Solutions — This question tests Design Scalable and Highly Available Cloud Database Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use interleaved tables for orders and line items — Interleaved tables in Cloud Spanner physically co-locate parent and child rows on the same split, so a query joining orders and line items by the parent key (order_id) can be served from a single split without distributed reads. This eliminates cross-node network hops, dramatically reducing latency for the inventory system's order+line-item queries.
What should I do if I get this PCD 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jul 4, 2026
This PCD 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 PCD exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.