# Cryo

> Cryo is an Apache-2.0, self-hosted Apache Iceberg maintenance control plane. Connect your lake and keep every table healthy without deciding when or how to optimize it — Cryo ranks the work from real query workload and explains every decision.

Cryo reads Apache Iceberg catalogs, ranks what is worth maintaining from real query workload, and admits the work to its native engine when the cluster has headroom. Sources and engines stay separate. The planner emits no SQL. Every decision is explained. These pages are the public docs.

Read this file, then answer only from the pages below. If a fact is not on one of them, say so.

## Pages

- [Overview](https://tech-pw.github.io/cryo/index.md): Self-hosted Apache Iceberg maintenance. Reads catalogs, plans the work, admits it when the engine has headroom.
- [Quickstart](https://tech-pw.github.io/cryo/quickstart/index.md): Clone the repo, run make up, seed five demo tables, and open localhost:5173.
- [Connect a lakehouse](https://tech-pw.github.io/cryo/onboarding/index.md): Connect a REST, Hive Metastore, Glue, Polaris or Nessie catalog to Cryo, choose S3 credentials, and run the first scan. Covers every field, what the scan reads, and the failures that look like success.
- [How Cryo fits](https://tech-pw.github.io/cryo/concepts/index.md): A source is where a table lives. A destination is where maintenance runs. Cryo holds the plan between them.
- [Architecture](https://tech-pw.github.io/cryo/architecture/index.md): Catalogs on the read side, engines on the write side, and the planner in between.
- [Maintenance](https://tech-pw.github.io/cryo/maintenance/index.md): Compact first, then clean up, in one fixed order no preset can change.
- [Health and cost](https://tech-pw.github.io/cryo/health/index.md): Grades run from A to F. A warning costs 8 points and a critical finding costs 20.
- [Tables](https://tech-pw.github.io/cryo/tables/index.md): A guided tour of Cryo's Tables page, covering the triage cards, the nightly maintenance funnel, the catalog list, quick views, filters, columns, the savings view and bulk actions.
- [Table detail](https://tech-pw.github.io/cryo/table-detail/index.md): A guided tour of Cryo's table detail page, covering the header, the actions menu and table settings, plus every section of the Overview, Schema & files, Snapshots, Maintenance, Config, Usage, Quality and Cost & Savings tabs, including archiving cold partitions.
- [Engines](https://tech-pw.github.io/cryo/engines/index.md): The planner emits no SQL. Trino and Spark each render the same plan in their own dialect.
- [Deployment](https://tech-pw.github.io/cryo/deployment/index.md): Helm on Kubernetes. Cryo plans and admits; Trino and Spark stay where they already run.
- [Reference](https://tech-pw.github.io/cryo/reference/index.md): What is in the box, what is not, and how Cryo compares with adjacent tools.

Full index: https://tech-pw.github.io/cryo/llms.txt