A data lake in S3 adds new files daily. Analysts want to query them in Athena without manually defining table schemas. What keeps table metadata up to date automatically?
A.Amazon EMR cluster
EMR processes data but doesn't populate a queryable metadata catalog for Athena.
B.AWS Glue crawler writing to the Glue Data Catalog
Correct. Crawlers infer schema and register tables in the Data Catalog automatically.
C.Amazon S3 Inventory
S3 Inventory lists object metadata, not data schemas or tables.
D.Amazon Redshift Spectrum
Spectrum queries external tables — it doesn't discover or catalog schemas.
Why this answer
A Glue crawler scans S3 data, infers schema and partitions, and creates/updates tables in the Glue Data Catalog — which Athena, EMR, and Redshift Spectrum all query against. Schedule it to keep metadata fresh.
Correct answer: B · Last reviewed 2026-10-26
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