Question 1,469 of 1,711
DEA-C01 Data Store Management Practice Question
A company uses Amazon Redshift for analytics. The data engineer notices that some queries are slow and the EXPLAIN plan shows a 'Seq Scan' on a large table. Which data store management action would most likely improve query performance?
⚠ Common exam trap
A common mix-up: candidates confuse ANALYZE or VACUUM with physical data organization, but neither command creates sort keys or distribution styles, which are the only mechanisms to avoid full table scans in Redshift.
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
✓
Define appropriate sort keys and distribution styles.
A Seq Scan indicates that Redshift is scanning the entire table because it lacks efficient data organization. Defining appropriate sort keys and distribution styles organizes data on disk and across nodes, enabling Redshift to use zone maps to skip large portions of data and to execute parallel, co-located joins, which directly reduces the need for full table scans.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Run the ANALYZE command to update table statistics.
Why it's wrong here
ANALYZE helps the optimizer but does not change the scan type.
- ✗
Enable automatic compression on the table.
Why it's wrong here
Compression reduces storage but not query execution time.
- ✓
Define appropriate sort keys and distribution styles.
Why this is correct
Sort keys and distribution styles can reduce data scanning and improve join performance.
- ✗
Run the VACUUM command to reclaim space.
Why it's wrong here
VACUUM reclaims space but does not improve sequential scans.
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Last reviewed: Jul 4, 2026
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