Hi Yuya, Ajantha, +1 to adding this as an optional REST catalog parameter. This seems useful for clients that need to flatten namespace trees and today have to issue one request per level.
Yufei On Wed, 6 May 2026 09:50:21 +0530, Ajantha Bhat [email protected] wrote: I agree that it can be helpful to return all level namespaces instead of the current level for some use cases to avoid multiple calls from clients. I had similar requirement <https://github.com/apache/polaris-tools/blob/167e74f952ce4df620dac03b2e1315f44b9c2535/iceberg-catalog-migrator/api/src/main/java/org/apache/polaris/iceberg/catalog/migrator/api/CatalogMigrator.java#L201-L209> before and had to keep custom code from the client side. The implementation can be a bit cleaner and simplified though. Added comments on the PR. - Ajantha On Wed, May 6, 2026 at 6:35 AM Yuya Ebihara [email protected] wrote: Hi everyone, I’d like to propose adding support for recursively listing namespaces in the REST catalog. Trino doesn’t support multi-level namespaces, so the Iceberg connector currently issues requests per namespace and flattens the results. This can become time-consuming when there are many namespaces or deeply nested structures. I believe this is not specific to Trino. A similar request was raised last year by the DuckDB community (https://github.com/apache/iceberg/issues/13453), although it was closed due to inactivity. I’ve opened a draft PR that introduces an optional ‘recursive’ parameter to the GET /v1/{prefix}/namespaces endpoint: https://github.com/apache/iceberg/pull/16199 I’d appreciate any feedback or suggestions. Thanks, Yuya Ebihara
