gravitino

Apache Gravitino is an open source data catalog that gives you a unified metadata layer across many sources: Hive, MySQL, S3, HDFS, Iceberg, Lance, and more. Apache 2.0 and free. The pitch is federation: instead of copying metadata into a central catalog, it reflects each source live, so what you query is what's actually there.

It plugs into Trino and Spark as a query catalog, supports geo-distributed metadata syncing, and adds access control and auditing across your estate. Self-hosting is via Docker or binary; this is a real infrastructure piece, not a small daemon, and it earns its complexity once you have multiple data systems to govern together.

For solo developers or small teams with one Postgres and one S3 bucket, this is overkill: a Hive Metastore or your DB's native catalog is enough. Larger teams with mixed engines and regions are the audience. It positions itself as an open alternative to Databricks Unity Catalog and Snowflake Polaris.

The catch: you commit to running a metadata service that becomes load-bearing for query engines. If it goes down or drifts, queries fail in confusing ways. Solid Apache project work, but a federated catalog is not a small thing to operate; budget the SRE time before you adopt.