Q:

Count distinct on elastic search

How to achieve count distinct function on elastic search type using sql4es driver?
Select distinct inv_number , count(1) from invoices;

But it returns the total count of the particular invoice number.

A:

Elasticsearch doesn't support deterministic DISTINCT counts (source). It supports only approximate distinct counters like "cardinality".
One way to count distincts in a deterministic way is to aggregate them using "terms" and count buckets from result.

