apache/shardingsphere · error · SQLFeatureNotSupportedException

createNClob

Error message

createNClob

What it means

ShardingSphere's JDBC driver does not implement the java.sql.Connection method createNClob (creating an empty java.sql.NClob for national-character (NCHAR/NVARCHAR/NCLOB) data). The abstract base class AbstractUnsupportedOperationConnection, which ShardingSphereConnection extends, overrides it as final and unconditionally throws SQLFeatureNotSupportedException. ShardingSphere does not implement client-side LOB factories, and NCLOB support is not part of its feature matrix, so the method always throws. The exception is thrown the moment the method is invoked on any connection produced by the ShardingSphere Driver.

Source

Thrown at jdbc/src/main/java/org/apache/shardingsphere/driver/jdbc/unsupported/AbstractUnsupportedOperationConnection.java:104

    
    @Override
    public Array createArrayOf(final String typeName, final Object[] elements) throws SQLException {
        throw new SQLFeatureNotSupportedException("createArrayOf");
    }
    
    @Override
    public final Blob createBlob() throws SQLException {
        throw new SQLFeatureNotSupportedException("createBlob");
    }
    
    @Override
    public Clob createClob() throws SQLException {
        throw new SQLFeatureNotSupportedException("createClob");
    }
    
    @Override
    public final NClob createNClob() throws SQLException {
        throw new SQLFeatureNotSupportedException("createNClob");
    }
    
    @Override
    public final SQLXML createSQLXML() throws SQLException {
        throw new SQLFeatureNotSupportedException("createSQLXML");
    }
    
    @Override
    public final Struct createStruct(final String typeName, final Object[] attributes) throws SQLException {
        throw new SQLFeatureNotSupportedException("createStruct");
    }
    
    @Override
    public final Properties getClientInfo() throws SQLException {
        throw new SQLFeatureNotSupportedException("getClientInfo");
    }
    
    @Override

View on GitHub (pinned to e952770a21)

Solutions

  1. Use setNString(int, String) or setNCharacterStream(int, Reader, long) on the PreparedStatement instead of an NClob object.
  2. If the backend column is a plain CLOB/VARCHAR, use setString/setClob(Reader) and drop national-character typing.
  3. For genuine NCLOB columns on Oracle/SQL Server backends, unwrap the native connection to create the NClob and verify the routed statement afterwards.
Defensive patterns

Strategy: try-catch

Validate before calling

boolean supportsOp = false;
try {
    connection.getMetaData(); // connection is alive
    // JDBC has no capability flag for individual methods; probe once per JVM:
    supportsOp = probeSupport(connection); // reflective/one-time guarded call
} catch (final SQLException ignored) {
}
// Simpler and recommended: capability-check by driver URL
boolean isShardingSphere = url.startsWith("jdbc:shardingsphere:");
if (isShardingSphere) {
    // skip the unsupported call, use the alternative API path
}

Try / catch

try {
    connection.createNClob(/* args */);
} catch (final SQLFeatureNotSupportedException e) {
    // expected on ShardingSphere connections: fall back to supported API
    log.debug("Driver does not support createNClob, using fallback", e);
}

Prevention

When it happens

Trigger: Calling Connection.createNClob() on a ShardingSphere connection.

Common situations: Code written against drivers with full JDBC 4 national-character support (Oracle, SQL Server); ORM nationalized-character mappings (Hibernate @Nationalized); frameworks that probe NClob capability.

Related errors

AI-assisted analysis of apache/shardingsphere@e952770a21 (2026-08-14). Data as JSON: /api/errors/b26a7e7921a26aab. Report an issue: GitHub.