DBS-C01 Monitoring and Troubleshooting Practice Question
A company uses Amazon Redshift and notices that queries are taking longer than usual. CloudWatch metrics show 'CPUUtilization' is high and 'DiskSpace' is low. Which TWO actions can help improve query performance?
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
✓
Add more nodes to the cluster
Adding nodes increases both compute capacity and storage, addressing high CPU and low disk space. Option E is correct because optimizing sort keys reduces the amount of data scanned per query, which lowers CPU usage and speeds up queries. Option A is incorrect because disabling concurrency scaling would reduce the cluster's ability to handle concurrent queries, increasing wait times. Option C is incorrect because Multi-AZ is not a feature of Amazon Redshift; it's used for RDS. Option D is incorrect because VACUUM reorganizes data but requires free disk space to operate; with low disk space, it may fail or not help.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Disable concurrency scaling to free resources
Why it's wrong here
Concurrency scaling improves performance by adding cluster capacity.
- ✓
Add more nodes to the cluster
Why this is correct
Adding nodes increases parallelism and resources for queries.
- ✗
Enable Multi-AZ to distribute load
Why it's wrong here
Redshift does not support Multi-AZ.
- ✗
Run VACUUM to reclaim space
Why it's wrong here
VACUUM requires free space and does not directly improve query speed.
- ✓
Optimize sort keys to reduce data scanned
Why this is correct
Better sort keys allow Redshift to skip more data during scans.
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Same concept, more angles
2 more ways this is tested on DBS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is using Amazon Redshift and notices that queries are running slowly. Which TWO system views should be used to identify the cause of the slow queries? (Choose TWO.)
medium- A.STV_TBL_PERM
- B.PG_TABLE_DEF
- ✓ C.STL_QUERY
- D.STL_LOAD_COMMITS
- ✓ E.SVV_QUERY_STATE
Why C: The correct answers are C and E. STL_QUERY contains detailed logs of all queries, including execution times, enabling identification of slow queries after execution. SVV_QUERY_STATE shows currently running queries, helping identify those that are running slowly. Option A (STV_TBL_PERM) is for table permissions, not performance. Option B (PG_TABLE_DEF) shows table definitions. Option D (STL_LOAD_COMMITS) shows load commit information.
Variation 2. A company is using Amazon Redshift and has a query that is running slowly. The DBA wants to identify if the query is I/O-bound. Which TWO metrics from Amazon CloudWatch can indicate I/O-bound queries?
medium- A.NetworkReceiveThroughput
- ✓ B.ReadIOPS
- C.CPUUtilization
- D.WriteIOPS
- ✓ E.ReadLatency
Why B: Options B and E are correct. ReadIOPS measures the number of read I/O operations per second, and ReadLatency measures the average time per read I/O operation. High values for these metrics indicate that the query is I/O-bound. Option A (NetworkReceiveThroughput) measures network throughput, not I/O. Option C (CPUUtilization) indicates CPU-bound workloads. Option D (WriteIOPS) measures write I/O, which is less likely to be the primary indicator for a slow query, and the question asks for the two metrics that can indicate I/O-bound queries; ReadIOPS and ReadLatency are the most direct I/O metrics.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 practice question is part of Courseiva's free Amazon Web Services 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 DBS-C01 exam.