如何配置 Debezium Mysql 连接器来生成原始键而不是 struct 或 json 对象？

Question

我正在使用 Debezium 来检测 MySql 源表中的更改。如何生成 Kafka 消息，使键为数字 ( Long) 值而不是 Json 对象？

我得到什么：

key: {"foo_id": 123} 
value: {"foo_id": 123, "bar": "blahblah", "baz": "meh......"}

我想要的是：

key: 123
value: {"foo_id": 123, "bar": "blahblah", "baz": "meh......"}

我的 FOO 表如下所示：

foo_id: INT
bar: VARCHAR 
baz: VARCHAR

请注意，我没有使用 avro，并且我已经尝试了以下几种组合（带和不带密钥变压器），但未能获得密钥Long。

"transforms": "unwrap,insertKey,extractKey",
"transforms.unwrap.type":"io.debezium.transforms.UnwrapFromEnvelope",
"transforms.unwrap.drop.tombstones":"false",
"transforms.insertKey.type":"org.apache.kafka.connect.transforms.ValueToKey",
"transforms.insertKey.fields":"foo_id",
"transforms.extractKey.type":"org.apache.kafka.connect.transforms.ExtractField$Key",
"transforms.extractKey.field":"foo_id",        
"key.converter" : "org.apache.kafka.connect.converters.LongConverter",
"key.converter.schemas.enable": "false", 
"value.converter" : "org.apache.kafka.connect.json.JsonConverter",
"value.converter.schemas.enable": "false"

我不确定 ValueToKey 或 ExtractField 适用于（MySQL）源，但我低于 NPE。

Caused by: java.lang.NullPointerException
        at org.apache.kafka.connect.transforms.ValueToKey.applyWithSchema(ValueToKey.java:85)
        at org.apache.kafka.connect.transforms.ValueToKey.apply(ValueToKey.java:65)
        at org.apache.kafka.connect.runtime.TransformationChain.lambda$apply$0(TransformationChain.java:44)
        at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execAndRetry(RetryWithToleranceOperator.java:128)
        at org.apache.kafka.connect.runtime.errors.RetryWithToleranceOperator.execAndHandleError(RetryWithToleranceOperator.java:162) 

Answer 1

找到了基于此的解决方案https://issues.jboss.org/browse/DBZ-689

{
...
    "config": {
    "transforms": "unwrap,insertKey,extractKey",
    "transforms.unwrap.type":"io.debezium.transforms.UnwrapFromEnvelope",
    "transforms.unwrap.drop.tombstones":"false",
    "transforms.insertKey.type":"org.apache.kafka.connect.transforms.ValueToKey",
    "transforms.insertKey.fields":"foo_id",
    "transforms.extractKey.type":"org.apache.kafka.connect.transforms.ExtractField$Key",
    "transforms.extractKey.field":"foo_id",        
    "key.converter" : "org.apache.kafka.connect.converters.IntegerConverter",
    "key.converter.schemas.enable": "true", 
    "value.converter" : "org.apache.kafka.connect.json.JsonConverter",
    "value.converter.schemas.enable": "false",
    "include.schema.changes": "false"  <-- this was missing
    }
}

现在，我将 foo_id 视为Integer（没什么大不了的Long）:)