public static void runCheck(ParseContext pctx) throws SemanticException {
    if (OperatorHealthCheckerHook.class.desiredAssertionStatus()) {
      OperatorHealthCheckerHook h = new OperatorHealthCheckerHook();
      Collection<Node> rootOps = new HashSet<>();
      rootOps.addAll(pctx.getTopOps().values());
      h.walkTree(rootOps);
    }
  }
Checks some operator quality rules.

Checks whenever operator ids are not reused.
Checks some level of expression/schema consistency
Some sanity checks on SelectOperators
ql/src/java/org/apache/hadoop/hive/ql/hooks/OperatorHealthCheckerHook.java