架构演进上的 Avro 反序列化错误

Question

我有2个模式：

模式1（旧模式）：

{
    "namespace": "com.org.package",
    "type": "record",
    "name": "EventModel",
    "fields": [
                    {
                        "name":"name",
                        "type":"string"
                    },
                    {
                        "name":"id",
                        "type":"long"
                    }
]
}

我用一个布尔字段更新了模式:

方案2（新方案）：

{
    "namespace": "com.org.package",
    "type": "record",
    "name": "EventModel",
    "fields": [
                    {
                        "name":"name",
                        "type":"string"
                    },
                    {
                        "name":"id",
                        "type":"long"
                    },
                    {
                        "name":"isActive",
                        "type":"boolean",
                        "default":false
                    }
]
}

kafka主题包含属于旧模式（schema1）的消息。更新使用者模式后，即使更新字段中存在默认值，使用者也无法反序列化旧模式消息。

根据Avro文档：

if the reader's record schema has a field that contains a default value, and writer's schema does not have a field with the same name, then the reader should use the default value from its field.
if the reader's record schema has a field with no default value, and writer's schema does not have a field with the same name, an error is signalled.

阿夫罗博士

我得到以下错误，而反序列化：

java.io.EOFException: null
    at org.apache.avro.io.BinaryDecoder.readBoolean(BinaryDecoder.java:140) ~[avro-1.9.1.jar!/:1.9.1]
    at org.apache.avro.io.ValidatingDecoder.readBoolean(ValidatingDecoder.java:77) ~[avro-1.9.1.jar!/:1.9.1]
    at org.apache.avro.generic.GenericDatumReader.readWithoutConversion(GenericDatumReader.java:194) ~[avro-1.9.1.jar!/:1.9.1]
    at org.apache.avro.specific.SpecificDatumReader.readField(SpecificDatumReader.java:136) ~[avro-1.9.1.jar!/:1.9.1]
    at org.apache.avro.generic.GenericDatumReader.readRecord(GenericDatumReader.java:237) ~[avro-1.9.1.jar!/:1.9.1]
    at org.apache.avro.specific.SpecificDatumReader.readRecord(SpecificDatumReader.java:123) ~[avro-1.9.1.jar!/:1.9.1]
    at org.apache.avro.generic.GenericDatumReader.readWithoutConversion(GenericDatumReader.java:170) ~[avro-1.9.1.jar!/:1.9.1]
    at org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:151) ~[avro-1.9.1.jar!/:1.9.1]
    at org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:144) ~[avro-1.9.1.jar!/:1.9.1]

当记录缺少字段时，为什么默认值未应用于使用者？任何帮助都非常感谢。提前致谢！

Answer 1

尝试将isActive的类型更改为boolean和null，而不仅仅是boolean。类似：

{
    "name": "isActive",
    "type": ["boolean", "null"],
    "default": false
}

它将使模式向后兼容。