// returns non-null string for validation fail
private void setConf(String varname, String key, String varvalue, boolean register)
throws IllegalArgumentException {
HiveConf conf = SessionState.get().getConf();
String value = new VariableSubstitution().substitute(conf, varvalue);
if (conf.getBoolVar(HiveConf.ConfVars.HIVECONFVALIDATION)) {
HiveConf.ConfVars confVars = HiveConf.getConfVars(key);
if (confVars != null && !confVars.isType(value)) {
StringBuilder message = new StringBuilder();
message.append("'SET ").append(varname).append('=').append(varvalue);