presto-main/src/main/java/io/prestosql/sql/planner/EffectivePredicateExtractor.java/Visitor/visitFilter
class Visitor:        @Override
        public Expression visitFilter(FilterNode node, Void context)
        {
            Expression underlyingPredicate = node.getSource().accept(this, context);

            Expression predicate = node.getPredicate();

            // Remove non-deterministic conjuncts
            predicate = filterDeterministicConjuncts(metadata, predicate);

            return combineConjuncts(metadata, predicate, underlyingPredicate);
        }