presto-main/src/main/java/io/prestosql/sql/planner/plan/StatisticAggregationsDescriptor.java/ColumnStatisticMetadataKeyDeserializer/deserialize
class ColumnStatisticMetadataKeyDeserializer:        @VisibleForTesting
        static ColumnStatisticMetadata deserialize(String value)
        {
            int separatorIndex = value.indexOf(':');
            checkArgument(separatorIndex >= 0, "separator not found: %s", value);
            String statisticType = value.substring(0, separatorIndex);
            String column = value.substring(separatorIndex + 1);
            return new ColumnStatisticMetadata(column, ColumnStatisticType.valueOf(statisticType));
        }