@Override
  public int execute() throws HiveException {
    String dcName = desc.getConnectorName();
    DataConnector connector = context.getDb().getDataConnector(dcName);
    if (connector == null) {
      throw new HiveException(ErrorMsg.DATACONNECTOR_NOT_EXISTS, dcName);
    }

    Map<String, String> params = connector.getParameters();
    // this call is to set the values from the alter descriptor onto the connector object
    doAlteration(connector);

    // This is the HMS metadata operation to modify the object
    context.getDb().alterDataConnector(connector.getName(), connector);
    return 0;
  }
Operation process of altering a data connector.
ql/src/java/org/apache/hadoop/hive/ql/ddl/dataconnector/alter/AbstractAlterDataConnectorOperation.java