Courseiva
← DEA-C01
Full test
Data Operations and Support →mediumMultiple Choice

DEA-C01 Data Operations and Support Practice Question

Exhibit

SELECT COUNT(*) FROM my_table WHERE ds = '2023-01-01';

Query results:
1073741824 bytes scanned

SELECT COUNT(*) FROM my_table WHERE ds = '2023-01-01' AND product_id = 12345;

Query results:
1073741824 bytes scanned

Refer to the exhibit. A data engineer runs two queries on an Athena table partitioned by 'ds'. Both queries scan the same amount of data. What does this indicate?

⚠ Common exam trap

The trap is assuming that simply having a partitioned table guarantees pruning — candidates forget that pruning requires an explicit predicate on the partition column in the WHERE clause, and equal scan sizes are the telltale sign it's missing.

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

✓

The partition column is not being used as a filter

If two queries that filter on different partition values scan the same amount of data, it means the partition column is not being used as a filter in the WHERE clause — Athena is scanning all partitions instead of pruning to the relevant ones. Partition pruning only occurs when the query includes a predicate on the partition column (e.g., WHERE ds = '2024-01-01'), so equal scan sizes across different filters indicate the predicate is missing or not applied.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✓

    The partition column is not being used as a filter

    Why this is correct

    Athena bills and scans by partition. Identical bytes scanned across both queries means neither predicate pruned partitions, so the ds column was not applied as a filter and the engine read the full table each time.

  • ✗

    The table does not have any partitions defined

    Why it's wrong here

    Absent partition definitions would mean no ds column exists, contradicting the stem's stated partitioning. Equal scan sizes instead point to filters that fail to prune, such as functions wrapped around ds; missing partitions is the correct diagnosis only when the schema shows none.

  • ✗

    The table is not partitioned

    Why it's wrong here

    Equal data scanned across queries filtering different ds values indicates partition pruning is not occurring, often because filters are not applied to the partition column. A genuinely unpartitioned table is a different condition, detectable from its schema rather than scan sizes.

  • ✗

    Partition pruning is working correctly

    Why it's wrong here

    Identical scan volumes across both queries mean the 'ds' filter was not pushed down, so every partition was read; genuine pruning would show one query scanning far less. It tempts engineers who equate equal scans with consistent behaviour, but pruning is confirmed only when a narrowed predicate reduces bytes scanned.

About these practice questions

One of 1,321 original DEA-C01 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →

How Courseiva writes practice questions · Editorial policy

JA

Written and reviewed by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint

This DEA-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 DEA-C01 exam.