ExamPark
Course menuSOA-C03

Exams / SOA-C03 / Study guide / RDS performance monitoring

RDS performance monitoring: SOA-C03 study notes and practice questions

What to know about RDS performance monitoring for the SOA-C03 exam, from the Monitoring, Logging, Analysis, Remediation, and Performance Optimization domain (22% of the exam guide), then 1 free question to test it. Part of the SOA-C03 study guide.

Last verified against current AWS documentation ·How we write our questions

What to know for the exam

RDS performance questions describe a slow or overloaded database and ask how to find or fix the cause.

Monitoring tools

Tool Shows
CloudWatch metrics CPUUtilization, FreeableMemory, DatabaseConnections, ReadIOPS/WriteIOPS, ReadLatency/WriteLatency, FreeStorageSpace, ReplicaLag
Enhanced Monitoring OS-level metrics (per-process CPU and memory) at up to 1-second granularity
Performance Insights Database load by wait event, SQL statement, host and user, so you can find the queries causing load
CloudWatch Database Insights A combined view of database health, building on Performance Insights
Database logs Slow query log, error log; publish them to CloudWatch Logs

Common fixes

Symptom Fix
Many short-lived connections (often from Lambda) exhaust the connection limit, CPU low RDS Proxy pools and reuses connections
CPU or memory consistently high Larger instance class, or tune the expensive queries found in Performance Insights
Read-heavy load Read replicas or Aurora Replicas, or a cache (ElastiCache)
Storage running out Storage autoscaling grows storage automatically
I/O limits on gp2 Move to gp3 or Provisioned IOPS storage
Settings need changing Edit the DB parameter group; static parameters need a reboot

Maintenance

  • Maintenance windows apply OS and engine patches; Multi-AZ keeps downtime short.
  • Minor version auto-upgrade can be turned on or off.
  • Instance class changes happen immediately or in the next maintenance window.

Common traps

  • Scaling the instance for a connection limit problem. RDS Proxy is cheaper and fixes the cause.
  • Expecting a parameter change to apply without a reboot. Static parameters need one; the parameter group shows “pending-reboot”.
  • Using Enhanced Monitoring to find slow queries. Performance Insights shows queries; Enhanced Monitoring shows the OS.

Try the 1 practice question

Practice RDS performance monitoringTake the free practice exam

Question 1

Medium ·Link to this question (question 1)

A pet insurer's claims intake uses AWS Lambda functions that write to an Amazon RDS for PostgreSQL DB instance.

During a marketing campaign, thousands of functions ran at once and the database rejected new connections with too many clients errors, although CPU stayed below 40 percent.

The team wants to absorb these bursts without changing the database engine or the instance size.

What should a CloudOps engineer do?

Choose one answer.

  1. A. Create a read replica and point half of the Lambda functions at it so that connections are split across two instances.
  2. B. Raise max_connections in the DB parameter group to the highest value allowed so that the instance accepts every connection.
  3. C. Put an RDS Proxy in front of the DB instance and have the Lambda functions connect to the proxy endpoint instead.
  4. D. Turn on Performance Insights and find the SQL statements that hold connections the longest, then tune them.
Show the answer and explanation

Answer: C

Explanation

Serverless clients open many short-lived connections, and with low CPU the limit is connections, not compute. RDS Proxy pools and reuses connections so that bursts reach the database as a manageable number. Read replicas cannot take writes, a higher max_connections risks memory, and Performance Insights diagnoses rather than fixes.

RDS Proxy pooling Lambda connections to an RDS database Many Lambda functions open connections to RDS Proxy. The proxy pools and reuses a smaller set of connections to the RDS for PostgreSQL DB instance. Lambda Lambda Lambda thousands at once RDS Proxy pools and reuses connections a few reused connections RDS for PostgreSQL same engine and size
Thousands of short Lambda connections land on the proxy, and the database sees a small pool it can handle.

Study

Want more on RDS performance monitoring? The 5 full-length practice sets have 6 more RDS performance monitoring questions, 325 in all, none of them in the free exam. One payment of $14.99, no subscription. See the practice sets

Study RDS performance monitoring

More Monitoring, Logging, Analysis, Remediation, and Performance Optimization topics