schema:
{
    "index-name": "examplekeys",
    "index-action": "create",
    "primary-key-type": "string",
    "fields": [
        {
            "field-name": "set",
            "field-type": "id",
            "field-options": { "cache-type": "none" }
        }
    ]
}
ingest:
[
  {
    "action": "set",
    "records": {
      "a": {
        "set": [ 2 ],
      },
      "b": {
        "set": 3,
      }
    }
  }
]
queries:
Row(set=2)
["a"]
Union(Row(set=3),Row(set=2))
["a","b"]