example_data.csv

output_from_sample_query.json

{
  "errors": [
    {
      "message": "Cannot return null for non-nullable field HelloAggregates.keys.",
      "locations": [
        {
          "line": 13,
          "column": 7
        }
      ],
      "path": [
        "hellos",
        "groupedAggregates",
        2,
        "keys",
        0
      ]
    }
  ],
  "data": {
    "hellos": {
      "groupedAggregates": [
        {
          "keys": [
            "world",
            "1",
            "3"
          ],
          "distinctCount": {
            "a": "1"
          }
        },
        {
          "keys": [
            "world3",
            "9",
            "5"
          ],
          "distinctCount": {
            "a": "1"
          }
        },
        {
          "keys": null,
          "distinctCount": {
            "a": "1"
          }
        }
      ]
    }
  }
}

sample_agg_query.graphql

query GetGrouped {
  hellos {
    groupedAggregates(groupBy: [B, C, D]) {
      keys
      distinctCount {
        a
      }
    }
  }
}

sample_table_ddl.sql

create table hello
(
    a varchar(100) not null
        primary key,
    b varchar(100),
    c integer,
    d integer
);