sql

Run ad-hoc DuckDB SQL queries over data files (CSV, JSONL, Parquet, and other DuckDB-readable formats). A single input file can be referenced as the view data; every file is also registered as a view named after its file stem.

# Aggregate a CSV
undatum sql "SELECT city, COUNT(*) AS n FROM data GROUP BY city" cities.csv

# Join two files (views named after file stems: orders, users)
undatum sql "SELECT * FROM orders JOIN users USING (user_id)" orders.csv users.parquet

# Save the result as Parquet
undatum sql "SELECT * FROM data WHERE amount > 100" sales.jsonl --output big.parquet --format parquet

Output formats: jsonl (default), csv, parquet (requires --output). DuckDB resources can be tuned with --duckdb-threads and --duckdb-memory. This is the ad-hoc query command for files; undatum db query runs SQL against a database URI.