无法使用 JDBC kafka-sink-connector 将 kafka 主题数据写入 postgres DB
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【中文标题】无法使用 JDBC kafka-sink-connector 将 kafka 主题数据写入 postgres DB【英文标题】：Unable to write kafka topic data into postgres DB using JDBC kafka-sink-connector 【发布时间】：2021-11-20 06:48:32 【问题描述】：我有一个 kafka 主题，我们在其中生成 avro 记录，架构如下所示。
"type": "record",
"name": "testValue",
"namespace": "com.test.testValue",
"fields": [
"name": "A",
"type": "string"
,
"name": "B",
"type": "string"
,
"name": "C",
"type":
"type": "bytes",
"logicalType": "decimal",
"precision": 8,
"scale": 2
,
"name": "D",
"type":
"type": "long",
"logicalType": "timestamp-millis"
,
"name": "E",
"type": [
"type": "record",
"name": "F",
"fields": [
"name": "G",
"type":
"type": "bytes",
"logicalType": "decimal",
"precision": 8,
"scale": 2
]
,
"type": "record",
"name": "H",
"fields": [
"name": "dummy",
"type": "boolean",
"default": true
]
,
"type": "record",
"name": "I",
"fields": [
"name": "J",
"type":
"type": "bytes",
"logicalType": "decimal",
"precision": 8,
"scale": 2
]
]
,
"name": "K",
"type":
"type": "long",
"logicalType": "timestamp-millis"
,
"name": "L",
"type": "boolean"
]
我对连接器有以下配置。
"name" : "test-sink-database",
"config" :
"connector.class": "io.confluent.connect.jdbc.JdbcSinkConnector",
"tasks.max": "1",
"connection.url": "jdbc:postgresql://database_url/postgres",
"topics": "test",
"connection.user": "postgres",
"connection.password": "password",
"table.name.format": "test_table",
"auto.create": "true",
"schema.registry.url": "http://schema-registry:8081",
"value.converter.schema.registry.url": "http://schema-registry:8081",
"key.converter.schema.registry.url": "http://schema-registry:8081",
"name": "test-sink-database",
"value.converter":"io.confluent.connect.avro.AvroConverter",
"key.converter":"io.confluent.connect.avro.AvroConverter",
"insert.mode":"insert"
出现以下错误。
Caused by: org.apache.kafka.connect.errors.ConnectException: io.confluent.connect.avro.Union (STRUCT) type doesn't have a mapping to the SQL database column type
完整的堆栈跟踪
org.apache.kafka.connect.errors.ConnectException: Exiting WorkerSinkTask due to unrecoverable exception.
at org.apache.kafka.connect.runtime.WorkerSinkTask.deliverMessages(WorkerSinkTask.java:560)
at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:321)
at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:224)
at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:192)
at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:177)
at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:227)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.kafka.connect.errors.ConnectException: io.confluent.connect.avro.Union (STRUCT) type doesn't have a mapping to the SQL database column type
at io.confluent.connect.jdbc.dialect.GenericDatabaseDialect.getSqlType(GenericDatabaseDialect.java:1727)
at io.confluent.connect.jdbc.dialect.PostgreSqlDatabaseDialect.getSqlType(PostgreSqlDatabaseDialect.java:215)
at io.confluent.connect.jdbc.dialect.GenericDatabaseDialect.writeColumnSpec(GenericDatabaseDialect.java:1643)
at io.confluent.connect.jdbc.dialect.GenericDatabaseDialect.lambda$writeColumnsSpec$33(GenericDatabaseDialect.java:1632)
at io.confluent.connect.jdbc.util.ExpressionBuilder.append(ExpressionBuilder.java:558)
at io.confluent.connect.jdbc.util.ExpressionBuilder$BasicListBuilder.of(ExpressionBuilder.java:597)
at io.confluent.connect.jdbc.dialect.GenericDatabaseDialect.writeColumnsSpec(GenericDatabaseDialect.java:1634)
at io.confluent.connect.jdbc.dialect.GenericDatabaseDialect.buildCreateTableStatement(GenericDatabaseDialect.java:1557)
at io.confluent.connect.jdbc.sink.DbStructure.create(DbStructure.java:91)
at io.confluent.connect.jdbc.sink.DbStructure.createOrAmendIfNecessary(DbStructure.java:61)
at io.confluent.connect.jdbc.sink.BufferedRecords.add(BufferedRecords.java:121)
at io.confluent.connect.jdbc.sink.JdbcDbWriter.write(JdbcDbWriter.java:66)
at io.confluent.connect.jdbc.sink.JdbcSinkTask.put(JdbcSinkTask.java:74)
at org.apache.kafka.connect.runtime.WorkerSinkTask.deliverMessages(WorkerSinkTask.java:538)
【问题讨论】：
【参考方案1】：我相信这是因为字段 E 的类型为 record。错误状态为(STRUCT) type doesn't have a mapping to the SQL database column type。您的E 定义如下
"name": "E",
"type": [
"type": "record",
"name": "F",
"fields": [
"name": "G",
"type":
"type": "bytes",
"logicalType": "decimal",
"precision": 8,
"scale": 2
]
,
"type": "record",
"name": "H",
"fields": [
"name": "dummy",
"type": "boolean",
"default": true
]
,
"type": "record",
"name": "I",
"fields": [
"name": "J",
"type":
"type": "bytes",
"logicalType": "decimal",
"precision": 8,
"scale": 2
]
]
JDBC 接收器无法处理嵌套良好的数据结构。您可以尝试使用CAST Single Message transform 将其转换为字符串，并检查它是否已正确推送到数据库中。另一种方法是用另一种 SMT 来推销价值，例如
"transforms": "flatten",
"transforms.flatten.type": "org.apache.kafka.connect.transforms.Flatten$Value"
【讨论】：
感谢您的快速支持，添加了以上配置但现在出现以下错误。引起：org.apache.kafka.connect.transforms.Flatten.buildWithSchema(Flatten.java:219) 处的 java.lang.NullPointerException 查看 issues.apache.org/jira/browse/KAFKA-6605 并尝试设置 "transforms.flatten.delimiter": "_" 它给了我同样的错误，即原因：java.lang.NullPointerException以上是关于无法使用 JDBC kafka-sink-connector 将 kafka 主题数据写入 postgres DB的主要内容，如果未能解决你的问题，请参考以下文章
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