DBS-C01 Workload-Specific Database Design Practice Question
A company runs a MySQL database on Amazon RDS for an e-commerce platform. The application performs frequent INSERT and UPDATE operations on the 'orders' table. The team notices an increase in disk I/O and CPU usage. They want to optimize the database for write-heavy workloads without changing the application. Which option is the MOST effective?
⚠ Common exam trap
The DBS-C01 exam often tests the misconception that Multi-AZ improves performance, when in fact it only provides redundancy and can slightly increase write latency due to synchronous replication to the standby instance.
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
✓
Increase the InnoDB buffer pool size
Increasing the InnoDB buffer pool size allows more data and indexes to be cached in memory, reducing disk I/O for write operations by delaying writes and enabling more efficient page merging. This directly addresses the high disk I/O and CPU usage from frequent INSERT and UPDATE operations without requiring application changes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Enable Multi-AZ deployment for redundancy
Why it's wrong here
Multi-AZ does not improve write performance; it adds synchronous replication.
- ✗
Change the storage engine to MyISAM
Why it's wrong here
MyISAM uses table-level locking, which would cause contention on writes.
- ✓
Increase the InnoDB buffer pool size
Why this is correct
A larger buffer pool reduces disk I/O by caching data and indexes in memory.
- ✗
Upgrade to Amazon Aurora MySQL
Why it's wrong here
Upgrading to Amazon Aurora MySQL is tempting as it offers superior performance, scalability, and availability compared to standard RDS MySQL, making it a strong choice for general database improvements and read-heavy workloads. However, for a write-heavy workload specifically experiencing high disk I/O and CPU on the primary instance, Aurora's architecture, while performant, does not inherently optimise the single-writer bottleneck or transaction processing efficiency in the most effective way without application changes. Its primary advantage lies in its distributed storage for read scaling and overall throughput, not a fundamental shift in write operation handling over standard MySQL.
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