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The database purpose-built for stream processing applications.
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JSON (and maybe AVRO/PROTOBUF) formats don't gracefully handle 0-fields for keys #6931

Open rodesai opened 3 years ago

rodesai commented 3 years ago

Suppose I create a stream with KEY_FORMAT='JSON' but no fields declared as KEY. When data is read, if the data is not a JSON object, ksqlDB throws deserialization errors. We should either reject the KEY_FORMAT or just be smarter about handling json primitives when deserializing.

$ cat statements.sql
CREATE STREAM CLICKS (IP_ADDRESS STRING, URL STRING, TIMESTAMP STRING)
    WITH (KAFKA_TOPIC = 'CLICKS',
          KEY_FORMAT = 'JSON',
          VALUE_FORMAT = 'JSON',
          TIMESTAMP = 'TIMESTAMP',
          TIMESTAMP_FORMAT = 'yyyy-MM-dd''T''HH:mm:ssXXX',
          PARTITIONS = 1);

CREATE TABLE DETECTED_CLICKS AS
    SELECT
        IP_ADDRESS AS KEY1,
        URL AS KEY2,
        TIMESTAMP AS KEY3,
        AS_VALUE(IP_ADDRESS) AS IP_ADDRESS,
        AS_VALUE(URL) AS URL,
        AS_VALUE(TIMESTAMP) AS TIMESTAMP
    FROM CLICKS WINDOW TUMBLING (SIZE 2 MINUTES, RETENTION 3650 DAYS)
    GROUP BY IP_ADDRESS, URL, TIMESTAMP
    HAVING COUNT(IP_ADDRESS) = 1;

CREATE STREAM RAW_DISTINCT_CLICKS (IP_ADDRESS STRING, URL STRING, TIMESTAMP STRING)
    WITH (KAFKA_TOPIC = 'DETECTED_CLICKS',
    KEY_FORMAT='JSON',
    VALUE_FORMAT = 'JSON');

CREATE STREAM DISTINCT_CLICKS AS
    SELECT
        IP_ADDRESS,
        URL,
        TIMESTAMP
    FROM RAW_DISTINCT_CLICKS
    WHERE IP_ADDRESS IS NOT NULL
    PARTITION BY IP_ADDRESS;

$ cat inputs.json
{
  "inputs": [
    {
      "topic": "CLICKS",
      "key": "\"10.0.0.1\"",
      "value": {
        "IP_ADDRESS": "10.0.0.1",
        "URL": "https://docs.confluent.io/current/tutorials/examples/kubernetes/gke-base/docs/index.html",
        "TIMESTAMP": "2021-01-17T14:50:43+00:00"
      }
    },
    {
      "topic": "CLICKS",
      "key": "\"10.0.0.2\"",
      "value": {
        "IP_ADDRESS": "10.0.0.12",
        "URL": "https://www.confluent.io/hub/confluentinc/kafka-connect-datagen",
        "TIMESTAMP": "2021-01-17T14:53:44+00:01"
      }
    },
    {
      "topic": "CLICKS",
      "key": "\"10.0.0.3\"",
      "value": {
        "IP_ADDRESS": "10.0.0.13",
        "URL": "https://www.confluent.io/hub/confluentinc/kafka-connect-datagen",
        "TIMESTAMP": "2021-01-17T14:56:45+00:03"
      }
    },
    {
      "topic": "CLICKS",
      "key": "\"10.0.0.1\"",
      "value": {
        "IP_ADDRESS": "10.0.0.1",
        "URL": "https://docs.confluent.io/current/tutorials/examples/kubernetes/gke-base/docs/index.html",
        "TIMESTAMP": "2021-01-17T14:50:43+00:00"
      }
    },
    {
      "topic": "CLICKS",
      "key": "\"10.0.0.2\"",
      "value": {
        "IP_ADDRESS": "10.0.0.12",
        "URL": "https://www.confluent.io/hub/confluentinc/kafka-connect-datagen",
        "TIMESTAMP": "2021-01-17T14:53:44+00:01"
      }
    },
    {
      "topic": "CLICKS",
      "key": "\"10.0.0.3\"",
      "value": {
        "IP_ADDRESS": "10.0.0.13",
        "URL": "https://www.confluent.io/hub/confluentinc/kafka-connect-datagen",
        "TIMESTAMP": "2021-01-17T14:56:45+00:03"
      }
    }
  ]
}

$ cat outputs.json
{
  "outputs": [
    {
      "topic": "DISTINCT_CLICKS",
      "key": "10.0.0.1",
      "value": {
        "URL": "https://docs.confluent.io/current/tutorials/examples/kubernetes/gke-base/docs/index.html",
        "TIMESTAMP": "2021-01-17T14:50:43+00:00"
      },
      "timestamp": 1610895043000
    },
    {
      "topic": "DISTINCT_CLICKS",
      "key": "10.0.0.12",
      "value": {
        "URL": "https://www.confluent.io/hub/confluentinc/kafka-connect-datagen",
        "TIMESTAMP": "2021-01-17T14:53:44+00:01"
      },
      "timestamp": 1610895164000
    },
    {
      "topic": "DISTINCT_CLICKS",
      "key": "10.0.0.13",
      "value": {
        "URL": "https://www.confluent.io/hub/confluentinc/kafka-connect-datagen",
        "TIMESTAMP": "2021-01-17T14:56:45+00:03"
      },
      "timestamp": 1610895225000
    }
  ]
}

$ ksql-testing-tool -i input.json -s statements.sql -o output.json
...
[2021-02-02 00:00:07,546] ERROR {"type":0,"deserializationError":{"target":"key","errorMessage":"Failed to deserialize key from topic: CLICKS. Can't convert type. sourceType: TextNode, requiredType: STRUCT< >, path: $","recordB64":null,"cause":["Can't convert type. sourceType: TextNode, requiredType: STRUCT< >, path: $","Can't convert type. sourceType: TextNode, requiredType: STRUCT< >"],"topic":"CLICKS"},"recordProcessingError":null,"productionError":null,"serializationError":null,"kafkaStreamsThreadError":null} (processing.CTAS_DETECTED_CLICKS_0.KsqlTopic.Source.deserializer:44)
[2021-02-02 00:00:07,546] WARN stream-thread [main] task [0_0] Skipping record due to deserialization error. topic=[CLICKS] partition=[0] offset=[5] (org.apache.kafka.streams.processor.internals.RecordDeserializer:88)
org.apache.kafka.common.errors.SerializationException: Failed to deserialize key from topic: CLICKS. Can't convert type. sourceType: TextNode, requiredType: STRUCT< >, path: $
Caused by: io.confluent.ksql.serde.json.KsqlJsonDeserializer$CoercionException: Can't convert type. sourceType: TextNode, requiredType: STRUCT< >, path: $
    at io.confluent.ksql.serde.json.KsqlJsonDeserializer.enforceFieldType(KsqlJsonDeserializer.java:155)
    at io.confluent.ksql.serde.json.KsqlJsonDeserializer.deserialize(KsqlJsonDeserializer.java:117)
    at io.confluent.ksql.serde.connect.ConnectFormat$StructToListDeserializer.deserialize(ConnectFormat.java:224)
    at io.confluent.ksql.serde.connect.ConnectFormat$StructToListDeserializer.deserialize(ConnectFormat.java:203)
    at io.confluent.ksql.serde.GenericDeserializer.deserialize(GenericDeserializer.java:59)
    at io.confluent.ksql.logging.processing.LoggingDeserializer.tryDeserialize(LoggingDeserializer.java:60)
    at io.confluent.ksql.logging.processing.LoggingDeserializer.deserialize(LoggingDeserializer.java:47)
    at org.apache.kafka.common.serialization.Deserializer.deserialize(Deserializer.java:60)
    at io.confluent.ksql.serde.tracked.TrackedDeserializer.deserialize(TrackedDeserializer.java:53)
    at org.apache.kafka.streams.processor.internals.SourceNode.deserializeKey(SourceNode.java:54)
    at org.apache.kafka.streams.processor.internals.RecordDeserializer.deserialize(RecordDeserializer.java:65)
    at org.apache.kafka.streams.processor.internals.RecordQueue.updateHead(RecordQueue.java:176)
    at org.apache.kafka.streams.processor.internals.RecordQueue.addRawRecords(RecordQueue.java:112)
    at org.apache.kafka.streams.processor.internals.PartitionGroup.addRawRecords(PartitionGroup.java:185)
    at org.apache.kafka.streams.processor.internals.StreamTask.addRecords(StreamTask.java:891)
    at org.apache.kafka.streams.TopologyTestDriver.enqueueTaskRecord(TopologyTestDriver.java:570)
    at org.apache.kafka.streams.TopologyTestDriver.pipeRecord(TopologyTestDriver.java:555)
    at org.apache.kafka.streams.TopologyTestDriver.pipeInput(TopologyTestDriver.java:533)
    at io.confluent.ksql.test.tools.TestExecutor.processSingleRecord(TestExecutor.java:514)
    at io.confluent.ksql.test.tools.TestExecutor.pipeRecordsFromProvidedInput(TestExecutor.java:475)
    at io.confluent.ksql.test.tools.TestExecutor.buildAndExecuteQuery(TestExecutor.java:196)
    at io.confluent.ksql.test.tools.KsqlTestingTool.executeTestCase(KsqlTestingTool.java:141)
    at io.confluent.ksql.test.tools.KsqlTestingTool.runWithTripleFiles(KsqlTestingTool.java:131)
    at io.confluent.ksql.test.tools.KsqlTestingTool.main(KsqlTestingTool.java:56)
Caused by: java.lang.IllegalArgumentException: Can't convert type. sourceType: TextNode, requiredType: STRUCT< >
    at io.confluent.ksql.serde.json.JsonSerdeUtils.invalidConversionException(JsonSerdeUtils.java:137)
    at io.confluent.ksql.serde.json.KsqlJsonDeserializer.invalidConversionException(KsqlJsonDeserializer.java:283)
    at io.confluent.ksql.serde.json.KsqlJsonDeserializer.enforceFieldTypesForStruct(KsqlJsonDeserializer.java:236)
    at io.confluent.ksql.serde.json.KsqlJsonDeserializer.enforceFieldType(KsqlJsonDeserializer.java:151)
    ... 23 more
    >>>>> Test failed: Topic DISTINCT_CLICKS. Expected <3> records but it was <0>
Actual records:
apurvam commented 3 years ago

Part of this is prioritizing support for JSON formats without keys. The other part is improving the error message to explain this lack of support for the time being.