架构演变上的 Avro 反序列化错误

Question

我有 2 个架构：

schema1（旧模式）：

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

我用布尔字段更新了架构：

schema2（新架构）：

{
    "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（模式 1）的消息。更新消费者架构后，即使更新字段中存在默认值，消费者也无法反序列化较旧的架构消息。

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.

Avro doc

反序列化时出现以下错误：

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]

为什么当记录缺少字段时，默认值不应用于消费者？ 非常感谢任何帮助。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。比如：

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

这将使架构向后兼容。