@Override
  public RelNode visit(HiveProject project) {
    for (RexNode expr : project.getProjects()) {
      checkExpr(expr);
    }
    return super.visit(project);
  }
Checks the query plan for conditions that would make the plan unsuitable for
materialized views or query caching:
- References to temporary or external tables
- References to non-deterministic functions.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/HiveRelOptMaterializationValidator.java