FrontendException {
// Set the logical plan values correctly in all the operators
PlanSetter ps = new PlanSetter(lp);
ps.visit();
UnionOnSchemaSetter setUnionOnSchema = new UnionOnSchemaSetter(lp, pigContext);
setUnionOnSchema.visit();
// run through validator
CompilationMessageCollector collector = new CompilationMessageCollector() ;
boolean isBeforeOptimizer = true;
validate(lp, collector, isBeforeOptimizer);