private RexNode convert(final ExprNodeFieldDesc fieldDesc) throws SemanticException {
RexNode rexNode = convert(fieldDesc.getDesc());
if (rexNode instanceof RexCall) {
// regular case of accessing nested field in a column
return cluster.getRexBuilder().makeFieldAccess(rexNode, fieldDesc.getFieldName(), true);
} else {
// This may happen for schema-less tables, where columns are dynamically
// supplied by serdes.
throw new CalciteSemanticException(
"Unexpected rexnode : " + rexNode.getClass().getCanonicalName(),
UnsupportedFeature.Schema_less_table);
}
}
