prestodb/presto · warning · SQLFeatureNotSupportedException

exported keys not supported

Error message

exported keys not supported

What it means

getExportedKeys() in PrestoDatabaseMetaData always throws SQLFeatureNotSupportedException ('exported keys not supported'). Presto does not maintain or enforce foreign keys, so the driver cannot list keys that reference a given table. This is a deliberate unimplemented stub of the java.sql.DatabaseMetaData interface.

Source

Thrown at presto-jdbc/src/main/java/com/facebook/presto/jdbc/PrestoDatabaseMetaData.java:1035

    @Override
    public ResultSet getPrimaryKeys(String catalog, String schema, String table)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("primary keys not supported");
    }

    @Override
    public ResultSet getImportedKeys(String catalog, String schema, String table)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("imported keys not supported");
    }

    @Override
    public ResultSet getExportedKeys(String catalog, String schema, String table)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("exported keys not supported");
    }

    @Override
    public ResultSet getCrossReference(String parentCatalog, String parentSchema, String parentTable, String foreignCatalog, String foreignSchema, String foreignTable)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("cross reference not supported");
    }

    @Override
    public ResultSet getTypeInfo()
            throws SQLException
    {
        return select("" +
                "SELECT TYPE_NAME, DATA_TYPE, PRECISION, LITERAL_PREFIX, LITERAL_SUFFIX,\n" +
                "CREATE_PARAMS, NULLABLE, CASE_SENSITIVE, SEARCHABLE, UNSIGNED_ATTRIBUTE,\n" +
                "FIXED_PREC_SCALE, AUTO_INCREMENT, LOCAL_TYPE_NAME, MINIMUM_SCALE, MAXIMUM_SCALE,\n" +
                "SQL_DATA_TYPE, SQL_DATETIME_SUB, NUM_PREC_RADIX\n" +

View on GitHub (pinned to 55bb57d202)

Solutions

  1. Skip exported-key introspection for Presto connections; no FKs exist
  2. Catch SQLFeatureNotSupportedException and substitute an empty result
  3. Use INFORMATION_SCHEMA queries for the available metadata instead
  4. Wrap the JDBC metadata access with a capability check / driver whitelist

Example fix

// before
ResultSet fk = meta.getExportedKeys(catalog, schema, table);
// after
ResultSet fk;
try {
    fk = meta.getExportedKeys(catalog, schema, table);
} catch (SQLFeatureNotSupportedException e) {
    fk = EMPTY_RESULT_SET;
}
Defensive patterns

Strategy: try-catch

Validate before calling

boolean supportsExportedKeys = !(meta instanceof com.facebook.presto.jdbc.PrestoDatabaseMetaData);

Type guard

boolean supportsExportedKeys = !(meta instanceof com.facebook.presto.jdbc.PrestoDatabaseMetaData);

Try / catch

try (ResultSet rs = meta.getExportedKeys(cat, schema, table)) { ... } catch (SQLFeatureNotSupportedException e) { /* empty FK set */ }

Prevention

When it happens

Trigger: Calling DatabaseMetaData.getExportedKeys(catalog, schema, table) on a Presto connection, typically from schema-browsing or data-modeling tools.

Common situations: ER diagram generators, DB migration/compare tools, ORMs introspecting referencing tables against Presto.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/8d9dd79f304bcbdf. Report an issue: GitHub.