presto-main/src/main/java/io/prestosql/cost/ScalarStatsCalculator.java/ScalarStatsCalculator/visitLiteral
class ScalarStatsCalculator:        @Override
        protected SymbolStatsEstimate visitLiteral(Literal node, Void context)
        {
            Object value = evaluate(metadata, session.toConnectorSession(), node);
            Type type = ExpressionAnalyzer.createConstantAnalyzer(metadata, session, ImmutableMap.of(), WarningCollector.NOOP).analyze(node, Scope.create());
            OptionalDouble doubleValue = toStatsRepresentation(metadata, session, type, value);
            SymbolStatsEstimate.Builder estimate = SymbolStatsEstimate.builder()
                    .setNullsFraction(0)
                    .setDistinctValuesCount(1);

            if (doubleValue.isPresent()) {
                estimate.setLowValue(doubleValue.getAsDouble());
                estimate.setHighValue(doubleValue.getAsDouble());
            }
            return estimate.build();
        }