Question 1,535 of 1,663
DBS-C01 Monitoring and Troubleshooting Practice Question
A company is using Amazon Redshift for data warehousing. The data engineering team notices that queries are taking longer than expected. The cluster has two nodes of type dc2.large. The database specialist checks the system tables and finds that many queries are using the disk for temporary storage. Which action should the specialist take to 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
✓
Upgrade the cluster to a node type with more memory, such as ra3.xlplus.
Disk spill to temporary storage indicates insufficient memory per node. Upgrading from dc2.large (∼15 GB RAM) to ra3.xlplus (∼32 GB RAM) doubles per-node memory, reducing disk spill and improving query performance. Option A is incorrect because distribution keys improve data distribution, not memory. Option B is incorrect because concurrency scaling manages concurrent queries, not per-query memory. Option C is incorrect because adding a node increases total cluster memory but per-node memory stays the same; disk spill occurs per node, so the problem persists.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Add distribution keys to the tables to improve data distribution.
Why it's wrong here
Adding distribution keys improves data distribution across slices but does not increase available memory per node. Disk spill is caused by insufficient memory, not poor data distribution.
- ✗
Enable concurrency scaling to offload queries to additional clusters.
Why it's wrong here
Concurrency scaling offloads queries to additional clusters to handle concurrency, but it does not increase memory for individual queries. Disk spill due to memory is not resolved by concurrency scaling.
- ✗
Increase the number of nodes to three to distribute the workload.
Why it's wrong here
Increasing the number of nodes adds more total cluster memory, but per-node memory remains the same (dc2.large). Disk spill happens when a query exceeds the memory of a single node; adding nodes does not fix per-node memory shortage.
- ✓
Upgrade the cluster to a node type with more memory, such as ra3.xlplus.
Why this is correct
Upgrading to ra3.xlplus nodes increases memory per node (from ~15 GB to ~32 GB), directly reducing the likelihood of disk spill for memory-intensive queries, thus improving query performance.
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Last reviewed: Jun 20, 2026
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