apache/seatunnel · error · UnsupportedOperationException

catalog not implements SupportsNamespaces so can't list data

Error message

catalog not implements SupportsNamespaces so can't list databases

What it means

IcebergCatalog.listDatabases delegates to SupportsNamespaces.listNamespaces on the wrapped Iceberg catalog; if the underlying catalog does not implement SupportsNamespaces, it throws UnsupportedOperationException saying it cannot list databases.

Source

Thrown at seatunnel-connectors-v2/connector-iceberg/src/main/java/org/apache/seatunnel/connectors/seatunnel/iceberg/catalog/IcebergCatalog.java:141

            return exists;
        } else {
            throw new UnsupportedOperationException(
                    "catalog not implements SupportsNamespaces so can't check database exists");
        }
    }

    @Override
    public List<String> listDatabases() throws CatalogException {
        if (catalog instanceof SupportsNamespaces) {
            List<String> databases =
                    ((SupportsNamespaces) catalog)
                            .listNamespaces().stream()
                                    .map(Namespace::toString)
                                    .collect(Collectors.toList());
            log.info("Fetched {} namespaces.", databases.size());
            return databases;
        } else {
            throw new UnsupportedOperationException(
                    "catalog not implements SupportsNamespaces so can't list databases");
        }
    }

    @Override
    public List<String> listTables(String databaseName)
            throws CatalogException, DatabaseNotExistException {
        List<String> tables =
                catalog.listTables(Namespace.of(databaseName)).stream()
                        .map(tableIdentifier -> toTablePath(tableIdentifier).getTableName())
                        .collect(Collectors.toList());
        log.info("Fetched {} tables.", tables.size());
        return tables;
    }

    @Override
    public boolean tableExists(TablePath tablePath) throws CatalogException {
        return catalog.tableExists(toIcebergTableIdentifier(tablePath));

View on GitHub (pinned to cf67b549a7)

Solutions

1. Switch to a namespace-aware catalog (HiveCatalog, HadoopCatalog, JDBC, Nessie) for this job
2. Avoid calling listDatabases for this catalog type; query specific namespaces/tables directly if supported
3. Extend the custom catalog to implement SupportsNamespaces.listNamespaces

Example fix

// before
catalog { name = "custom-catalog" } // no SupportsNamespaces
// after
catalog { name = "jdbc", uri = "jdbc:metadata:..." } // supports namespaces

if (!(icebergCatalog instanceof SupportsNamespaces)) {
  throw new IllegalStateException("Catalog cannot list databases; pick a SupportsNamespaces catalog");
}

if (catalog instanceof SupportsNamespaces) {
    List<Namespace> namespaces = ((SupportsNamespaces) catalog).listNamespaces();
}

try {
  List<String> dbs = seaTunnelCatalog.listDatabases();
} catch (UnsupportedOperationException e) {
  // use known namespace list from config instead
}

When it happens

Trigger: listDatabases is invoked (e.g. by catalog browsing, sync tools, or pre-checks) against an Iceberg catalog implementation that only implements the base Catalog interface.

Common situations: Pointing the connector at a minimal/custom catalog implementation without namespace support; running list-features tooling against a catalog type that can't enumerate namespaces.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• catalog not implements SupportsNamespaces so can't check dat
• Table not exist
• table not exist
• Only support sql: delete from ... where ..., Not support: {}
• Unsupported action type:

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/fc3ea316ed6bf29f. Report an issue: GitHub.