DEA-C01 Practice Question 14: Athena per Query Scan Limit
AWS Certified Data Engineer – Associate (DEA-C01) · Test 2 · question 4 of 10
Business analysts run ad hoc Amazon Athena queries in a dedicated workgroup. A few times a month, someone runs a query with no partition filter against a multi-terabyte table, and a single query scans tens of terabytes. The finance team wants any single query in this workgroup that scans more than 1 TB to be stopped automatically. It does not want to block the analysts' normal smaller queries.
What should the data engineer configure?
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Answer:
Athena workgroups offer two kinds of data usage controls, and the question depends on the difference between them. The per-query control limit "specifies the total amount of data scanned per query. If any query that runs in the workgroup exceeds the limit, it is canceled." Cancellation is the fixed default action. Each workgroup has one per-query limit, and it applies to every query run there. Queries under 1 TB are unaffected, which matches the requirement exactly.
Option A uses the other kind of control. Workgroup-wide limits add up data scanned over an hour or a day and trigger CloudWatch alarms and SNS notifications. The documentation states that "queries are not automatically canceled when a threshold is reached." The runaway query would finish and be billed.
Option B only helps when the *identical* query is repeated within the reuse window. The first run of every expensive query still scans everything, and a new filter or table makes a new query.
Option D is far too blunt. Disabling the workgroup stops *every* analyst's queries, including the small ones the team wants to keep. It is also reactive: the alarm fires on metrics that are published after data has already been scanned.
Reference: Configure per-query and per-workgroup data usage controls