Google PCA Practice Question: Analysing and Optimising Technical and Business Processes
Your company uses Cloud SQL for PostgreSQL to support a web application. During peak hours, the database experiences high read load, causing slow query responses. You need to improve read performance while ensuring data consistency. What should you do?
⚠ Common exam trap
The trap here is assuming that high availability (HA) can be used for read scaling; HA provides failover, not additional read capacity.
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
✓
Create a read replica and configure the application to send read queries to the replica.
Creating a read replica allows read queries to be offloaded from the primary instance, directly addressing high read load and improving performance. It scales reads horizontally and is a standard pattern for read-heavy applications. Other options either do not distribute read traffic or provide only temporary vertical scaling.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the machine type of the Cloud SQL instance to a larger size with more vCPUs and memory.
Why it's wrong here
Increasing the machine type provides more resources to the primary instance, which can improve performance temporarily. However, it does not specifically address read scaling and may be more expensive than adding read replicas. It also does not distribute the read load; all queries still hit the same instance. This is a vertical scaling approach that may not be cost-effective for read-heavy workloads.
- ✗
Enable high availability (HA) on the Cloud SQL instance to distribute read traffic across multiple zones.
Why it's wrong here
Enabling HA creates a standby instance in a different zone for failover, but the standby does not serve read traffic. HA is designed for availability, not for scaling read operations. It does not improve read performance because all reads still go to the primary instance. Therefore, this option does not address the high read load.
- ✗
Configure Cloud SQL to use SSD storage instead of HDD to improve read throughput.
Why it's wrong here
Cloud SQL already uses SSD storage by default for most instance types, and changing to SSD (if not already) can improve I/O performance. However, it does not scale read operations horizontally and may not fully alleviate high read load during peak hours. This is a storage-level optimization, not a read-scaling solution. It is less effective than adding read replicas for read-heavy workloads.
- ✓
Create a read replica and configure the application to send read queries to the replica.
Why this is correct
Creating a read replica offloads read traffic from the primary instance, improving read performance. Cloud SQL read replicas are asynchronously replicated, which may introduce slight replication lag, but for many read-heavy workloads, this is acceptable. The application can be configured to direct read queries to the replica, reducing load on the primary and improving response times. This approach maintains data consistency for reads that can tolerate eventual consistency.
Go deeper
Related to this question
Learn chapter
Google Cloud Compute Options Overview
Key term
Data
Data is raw, unprocessed information, like numbers, words, or measurements, that can be stored, processed, and analyzed by computers.
Key term
Read replica
A read replica is a copy of a database that is used only to handle read queries, taking load off the primary database.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
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