SQL: MIN/MAX/AVG/SUM/PERCENTILE/PERCENTILE RANK handling on NULL values

[astefan]

sql> select max(languages) max, min(languages) min, sum(languages) sum, percentile(languages, 80) percent, percentile_rank(languages, 3) percent_rank, avg(languages) avg from test_emp group by languages;
      max      |      min      |      sum      |    percent    | percent_rank  |      avg
---------------+---------------+---------------+---------------+---------------+---------------
-Infinity      |Infinity       |0.0            |NaN            |NaN            |NaN
1.0            |1.0            |15.0           |1.0            |100.0          |1.0
2.0            |2.0            |38.0           |2.0            |100.0          |2.0
3.0            |3.0            |51.0           |3.0            |100.0          |3.0
4.0            |4.0            |72.0           |4.0            |0.0            |4.0
5.0            |5.0            |105.0          |5.0            |0.0            |5.0

The first line is for null values in the languages field. Shouldn't MIN and MAX of null values return a null? Same question for SUM. Not so sure about PERCENTILE and PERCENTILE_RANK though... ES returns null for these two. If MIN and MAX would return null probably the same should be done for AVG.
Opening this one up for discussion.

[elasticmachine]

Pinging @elastic/es-search-aggs

[costin]

The issue here is that as the bucket doesn't contain any entries, the aggs return default values (since Aggs use primitives which cannot be nullified).