apache-kafka - 为什么在 Kafka Connect 中使用 JDBC Sink Connector 无法删除记录

Question

我的接收器属性:

{
  "name": "jdbc-oracle",
  "config": {
    "connector.class": "io.confluent.connect.jdbc.JdbcSinkConnector",
    "tasks.max": "1",
    "topics": "orders",
    "connection.url": "jdbc:oracle:thin:@10.1.2.3:1071/orac",
    "connection.user": "ersin",
    "connection.password": "ersin!",
    "auto.create": "true",
    "delete.enabled": "true",
    "pk.mode": "record_key",
    "pk.fields": "id",
    "insert.mode": "upsert",
    "plugin.path": "/home/ersin/confluent-5.4.1/share/java/",
    "name": "jdbc-oracle"
  },
  "tasks": [
    {
      "connector": "jdbc-oracle",
      "task": 0
    }
  ],
  "type": "sink"
}

我的 connect-avro-distributed.properties :

bootstrap.servers=10.0.0.0:9092

group.id=connect-cluster

key.converter=io.confluent.connect.avro.AvroConverter
key.converter.schema.registry.url=http://10.0.0.0:8081
value.converter=io.confluent.connect.avro.AvroConverter
value.converter.schema.registry.url=http://10.0.0.0:8081

config.storage.topic=connect-configs
offset.storage.topic=connect-offsets
status.storage.topic=connect-statuses

config.storage.replication.factor=1
offset.storage.replication.factor=1
status.storage.replication.factor=1

internal.key.converter=org.apache.kafka.connect.json.JsonConverter
internal.value.converter=org.apache.kafka.connect.json.JsonConverter
internal.key.converter.schemas.enable=false
internal.value.converter.schemas.enable=false

我发送这样的数据:

./bin/kafka-avro-console-producer \
  --broker-list 10.0.0.0:9092 --topic orders \
  --property parse.key="true" \
  --property key.schema='{"type":"record","name":"key_schema","fields":[{"name":"id","type":"int"}]}' \
  --property key.separator="$" \
  --property value.schema='{"type":"record","name":"myrecord","fields":[{"name":"id","type":["null","int"],"default": null},{"name":"product","type": ["null","string"],"default": null}, {"name":"quantity", "type":  ["null","int"],"default": null}, {"name":"price","type":  ["null","int"],"default": null}]}' \
  --property schema.registry.url=http://10.0.0.0:8081

我可以像这样在 oracle 上插入或更新数据

{"id":3}${"id": {"int":2}, "product": {"string":"Yağız Gülbahar"}, "quantity": {"int":1071}, "price": {"int":1453}}

但是当我用它来删除oracle上的记录时，它无法删除数据，只能将列更新为空

{"id":2}${"id": null, "product": null , "quantity": null , "price": null }

我该如何解决这个问题？

提前致谢

Answer 1

实际上您需要生成一个墓碑记录。在 Kafka 中，使用 JDBC Sink Connector 进行删除的工作原理如下:

The connector can delete rows in a database table when it consumes a tombstone record, which is a Kafka record that has a non-null key and a null value. This behavior is disabled by default, meaning that any tombstone records will result in a failure of the connector, making it easy to upgrade the JDBC connector and keep prior behavior.

Deletes can be enabled with delete.enabled=true, but only when the pk.mode is set to record_key. This is because deleting a row from the table requires the primary key be used as criteria.

Enabling delete mode does not affect the insert.mode.

另请注意，此类记录只有在 delete.retention.ms 毫秒后才会被删除，目前默认为 24​​ 小时。

---

因此，请尝试减少属性中的此配置，看看它是否有效。为此，您需要运行以下命令:

 ./bin/kafka-topics.sh \
    --alter \
    --zookeeper localhost:2181 \
    --topic orders \
    --config retention.ms=100 

---

现在，一旦配置完成，您所需要做的就是生成一条具有非空键和空值的消息。请注意，由于用户输入被解析为 UTF-8，因此无法使用 Kafka Console Consumer 来生成空记录。 因此，

{"id":2}${"id": null, "product": null , "quantity": null , "price": null }

不是真正的墓碑消息。

但是您可以使用kafkacat但它只适用于 JSON 消息:

# Produce a tombstone (a "delete" for compacted topics) for key 
# "abc" by providing an empty message value which -Z interpretes as NULL:

echo "abc:" | kafkacat -b mybroker -t mytopic -Z -K:

但在您的情况下，这不起作用，因为您需要发送 Avro 消息。因此，我建议用您最喜欢的语言编写一个非常简单的 Avro Producer，以便您可以实际发送墓碑消息。