presto-main/src/main/java/io/prestosql/cost/SymbolStatsEstimate.java/SymbolStatsEstimate/isSingleValue
class SymbolStatsEstimate:    public boolean isSingleValue()
    {
        return distinctValuesCount == 1.0
                && Double.compare(lowValue, highValue) == 0
                && !isInfinite(lowValue);
    }