Maintain DuckLake Storage

Compact files, expire snapshots, and free storage.

1. Run All Maintenance

ondatrasql checkpoint

Runs all steps in order: flush → expire → merge → rewrite → cleanup → orphaned.

2. Or Run Individual Steps

ondatrasql flush                  # Materialize inlined data to Parquet
ondatrasql expire                 # Remove old snapshot metadata
ondatrasql merge                  # Combine small files
ondatrasql rewrite                # Compact files with many deletes
ondatrasql cleanup                # Delete unused files
ondatrasql orphaned               # Remove stray files from failed writes

3. Schedule Weekly

Use your system’s cron (or systemd timer, k8s CronJob, Airflow, etc.) to run maintenance weekly:

0 3 * * 0 cd /path/to/project && ondatrasql checkpoint

Customizing

Maintenance SQL lives in sql/: checkpoint.sql, flush.sql, merge.sql, expire.sql, rewrite.sql, cleanup.sql, and orphaned.sql. Edit them directly to adjust thresholds or add custom logic.

See DuckLake: Recommended Maintenance for details on each operation.