Format and validate Athena SQL queries with partition projection helpers.
Last verified: May 2026
Output will appear here...The Athena Query Formatter prettifies and formats Amazon Athena SQL queries for better readability. Athena uses Presto/Trino SQL syntax with extensions for querying data in S3, and complex queries with nested subqueries, CTEs, and partition predicates can become difficult to read without proper formatting. This tool applies consistent indentation, keyword capitalization, and line breaks to make your Athena queries cleaner for code reviews, documentation, and collaboration.
The tool focuses on formatting and prettification rather than full syntax validation. It handles standard SQL and Presto/Trino syntax patterns. For syntax validation, run the query with EXPLAIN in the Athena console to check for errors without scanning data.
Yes. The formatter recognizes Athena and Presto/Trino-specific syntax including UNNEST, UNLOAD, CREATE TABLE AS, MSCK REPAIR TABLE, and partition projection expressions.
A teammate sends you a 200-line Athena query for ALB log analysis that's a single dense block of SQL. You paste into the formatter and get a properly-structured query with each CTE on its own block, JOIN ON clauses aligned, and partition predicates clearly visible. You immediately spot that the query is missing a partition predicate on dt, meaning it scans 18 months of logs instead of 1 day — a $200 cost vs $0.50. You add the predicate before running, save the team $200 and cut runtime from 12 minutes to 8 seconds.
The formatter parses Athena/Presto/Trino SQL using a SQL-aware tokenizer, then re-emits the query with consistent indentation, uppercase keywords (SELECT, FROM, WHERE, etc.), aligned column lists, and proper line breaks for clauses, subqueries, and CTEs. It preserves Athena-specific syntax (UNNEST, UNLOAD, partition projection) and JSON path expressions.
Athena charges $5 per TB scanned. A query with proper partition predicates can scan 100 MB instead of 100 TB — a 1,000x cost difference. Always confirm WHERE clauses on partitioned tables before running expensive queries. EXPLAIN shows the partitions to be scanned without actually running the query.
Athena's COLUMNAR formats (Parquet, ORC) provide 10-90x better cost-efficiency than CSV/JSON for analytical queries — Athena only reads the columns referenced. Always convert raw data to Parquet via Glue or CTAS before querying repeatedly. The conversion cost pays back within ~10 queries.
Athena workgroup query result location settings let you isolate results per team and apply per-workgroup query cost limits. Setting MaxBytesScanned per query is cheap insurance against runaway queries from a junior analyst doing SELECT * on the entire table.
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