I’ve got a nosql database (Azure CosmosDB) with a collection that contains, in addition to other properties, records in this format.

{
    "id": "0574100324396001",
    "StoreId": 574,
    "TransactionSequenceNumber": 3960,
    "UnitSession": {
        "User": "Tom Smith"
        "StoreId": 574,
        "TillNumber": 1
    }
}

The records may get created in any order however I want to ensure that for a given StoreId and TillNumber, that the TransactionSequenceNumber are sequential and that there are no gaps e.g. for StoreId 574, TillNumber 1, there are TransactionSequenceNumbers 3960, 3958, 3959, 3961.

How could I go about doing this?