Compatibility of Avro contract with enum

问题

I have an existing avro schema

{
"name": "myenum",
"type": {
        "type": "enum",
        "name": "Suit",
        "symbols": ["SPADES", "HEARTS", "DIAMONDS", "CLUBS"]
    },
"default": null
}

I want to add null to be the default and updating the contract to the following result in backward compatibility error. what can be done to solve this issue

{
"name": "myenum",
"type": [ null, {
        "type": "enum",
        "name": "Suit",
        "symbols": ["SPADES", "HEARTS", "DIAMONDS", "CLUBS"]
    }],
"default": null
}

回答1:

There is a problem with the null that is been added.

i.e.

{
    "name": "myenum",
    "type": [ null, { <- problem
        "type": "enum",
        "name": "Suit",
        "symbols": ["SPADES", "HEARTS", "DIAMONDS", "CLUBS"]
    }],
    "default": null
}

It should be within quotes: null => "null". So updated definition will be like:

{
    "name": "myenum",
    "type": [ "null", { <- change
        "type": "enum",
        "name": "Suit",
        "symbols": ["SPADES", "HEARTS", "DIAMONDS", "CLUBS"]
    }],
    "default": null
}

来源：https://stackoverflow.com/questions/65073407/compatibility-of-avro-contract-with-enum