Hi Dev,
I hope this email finds you well.
I am using Flink 1.20.1 with this environment:
> java 11.0.26 2025-01-21 LTS
> Java(TM) SE Runtime Environment 18.9 (build 11.0.26+7-LTS-187)
> Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.26+7-LTS-187, mixed
> mode)
> OS: Windows 11
> IDE: VSCode
I send the data from the producer Python and Flink consumer uses this logic:
*Read Kafka Stock topic with Datastream API:*
This is how I read the kafka topics:
> KafkaSource<Stock> kafkaSource = createKafkaSource(env, inputProperties,
> new JsonDeserializationSchema<>(Stock.class));
> DataStream<Stock> stockNoWatermark = env.fromSource(kafkaSource,
> WatermarkStrategy.noWatermarks(), "Kafka source");
*After that, I convert the data to Table SQL because I prefer to manipulate
the data using SQL:*
>
> Table stockTableWatermark = tableEnv.fromDataStream(
> stockNoWatermark,
> Schema.newBuilder()
> .column("event_type", DataTypes.STRING())
> .column("exchange", DataTypes.INT())
> .column("id", DataTypes.BIGINT())
> .column("price", DataTypes.FLOAT())
> .column("sequence_number", DataTypes.BIGINT())
> .column("size", DataTypes.INT())
> .column("symbol", DataTypes.STRING())
> .column("tape", DataTypes.STRING())
> .column("timestamp", DataTypes.TIMESTAMP_LTZ(3))
> .column("trf_id", DataTypes.STRING())
> .column("trf_timestamp", DataTypes.STRING())
> .column("actual_timestamp", DataTypes.STRING())
> .watermark("timestamp", "`timestamp` - INTERVAL '1' SECOND")
> .build()
*The result from stockTableWatermark like this:*
> 5> +I[T, 2015, 4991, 158.85, 282034, 95, GOOG, null,
> +57465-02-11T05:36:48Z, null, null, 2025-06-30 00:10:53.808]
> 5> +I[T, 4231, 4642, 181.31, 751310, 35, NVDA, null,
> +57465-02-11T05:36:51Z, null, null, 2025-06-30 00:10:53.811]
> 5> +I[T, 2692, 2536, 236.31, 435106, 50, AAPL, null,
> +57465-02-11T05:36:58Z, null, null, 2025-06-30 00:10:53.818]
> 5> +I[T, 3531, 1780, 137.95, 879217, 15, NVDA, null,
> +57465-02-11T05:37:31Z, null, null, 2025-06-30 00:10:53.851]
> 5> +I[T, 2046, 2779, 340.58, 658954, 24, NVDA, null,
> +57465-02-11T05:37:37Z, null, null, 2025-06-30 00:10:53.857]
*I aggregated with tumbling based on the column timestamp:*
> Table resultTable = stockTableWatermark
> .window(Tumble.over(lit(1).minutes()).on($("timestamp")).as("window")) //
> define window
> .groupBy($("symbol"), $("window")) // group by key and window
> .select(
> $("symbol").as("ticker"),
> $("window").start(),
> $("window").end(),
> $("sequence_number").count().as("trades")
> );
*But why, when I print out the output of resultTable, it shows empty?*
*And this is the last log message:*
> 14:48:34,317 INFO
> org.apache.flink.connector.base.source.reader.SourceReaderBase [] - Adding
> split(s) to reader: [[Partition: dev-stock-topic-0, StartingOffset: -2,
> StoppingOffset: -9223372036854775808]]
> 14:48:34,340 INFO org.apache.kafka.clients.consumer.ConsumerConfig
> [] - ConsumerConfig values:
> allow.auto.create.topics = true
> auto.commit.interval.ms = 5000
> auto.include.jmx.reporter = true
> auto.offset.reset = earliest
> bootstrap.servers = [localhost:9092]
> check.crcs = true
> client.dns.lookup = use_all_dns_ips
> client.id = flink-dev-group-stock-consumer-4
> client.rack =
> connections.max.idle.ms = 540000
> default.api.timeout.ms = 60000
> enable.auto.commit = false
> exclude.internal.topics = true
> fetch.max.bytes = 52428800
> fetch.max.wait.ms = 500
> fetch.min.bytes = 1
> group.id = flink-dev-group-stock-consumer
> group.instance.id = null
> heartbeat.interval.ms = 3000
> interceptor.classes = []
> internal.leave.group.on.close = true
> internal.throw.on.fetch.stable.offset.unsupported = false
> isolation.level = read_uncommitted
> key.deserializer = class
> org.apache.kafka.common.serialization.ByteArrayDeserializer
> max.partition.fetch.bytes = 1048576
> max.poll.interval.ms = 300000
> max.poll.records = 500
> metadata.max.age.ms = 300000
> metric.reporters = []
> metrics.num.samples = 2
> metrics.recording.level = INFO
> metrics.sample.window.ms = 30000
> partition.assignment.strategy = [class
> org.apache.kafka.clients.consumer.RangeAssignor, class
> org.apache.kafka.clients.consumer.CooperativeStickyAssignor]
> receive.buffer.bytes = 65536
> reconnect.backoff.max.ms = 1000
> reconnect.backoff.ms = 50
> request.timeout.ms = 30000
> retry.backoff.ms = 100
> sasl.client.callback.handler.class = null
> sasl.jaas.config = null
> sasl.kerberos.kinit.cmd = /usr/bin/kinit
> sasl.kerberos.min.time.before.relogin = 60000
> sasl.kerberos.service.name = null
> sasl.kerberos.ticket.renew.jitter = 0.05
> sasl.kerberos.ticket.renew.window.factor = 0.8
> sasl.login.callback.handler.class = null
> sasl.login.class = null
> sasl.login.connect.timeout.ms = null
> sasl.login.read.timeout.ms = null
> sasl.login.refresh.buffer.seconds = 300
> sasl.login.refresh.min.period.seconds = 60
> sasl.login.refresh.window.factor = 0.8
> sasl.login.refresh.window.jitter = 0.05
> sasl.login.retry.backoff.max.ms = 10000
> sasl.login.retry.backoff.ms = 100
> sasl.mechanism = GSSAPI
> sasl.oauthbearer.clock.skew.seconds = 30
> sasl.oauthbearer.expected.audience = null
> sasl.oauthbearer.expected.issuer = null
> sasl.oauthbearer.jwks.endpoint.refresh.ms = 3600000
> sasl.oauthbearer.jwks.endpoint.retry.backoff.max.ms = 10000
> sasl.oauthbearer.jwks.endpoint.retry.backoff.ms = 100
> sasl.oauthbearer.jwks.endpoint.url = null
> sasl.oauthbearer.scope.claim.name = scope
> sasl.oauthbearer.sub.claim.name = sub
> sasl.oauthbearer.token.endpoint.url = null
> security.protocol = PLAINTEXT
> security.providers = null
> send.buffer.bytes = 131072
> session.timeout.ms = 45000
> socket.connection.setup.timeout.max.ms = 30000
> socket.connection.setup.timeout.ms = 10000
> ssl.cipher.suites = null
> ssl.enabled.protocols = [TLSv1.2, TLSv1.3]
> ssl.endpoint.identification.algorithm = https
> ssl.engine.factory.class = null
> ssl.key.password = null
> ssl.keymanager.algorithm = SunX509
> ssl.keystore.certificate.chain = null
> ssl.keystore.key = null
> ssl.keystore.location = null
> ssl.keystore.password = null
> ssl.keystore.type = JKS
> ssl.protocol = TLSv1.3
> ssl.provider = null
> ssl.secure.random.implementation = null
> ssl.trustmanager.algorithm = PKIX
> ssl.truststore.certificates = null
> ssl.truststore.location = null
> ssl.truststore.password = null
> ssl.truststore.type = JKS
> value.deserializer = class
> org.apache.kafka.common.serialization.ByteArrayDeserializer
> 14:48:34,413 WARN org.apache.kafka.clients.consumer.ConsumerConfig
> [] - These configurations '[client.id.prefix,
> partition.discovery.interval.ms, aws.secret.username,
> aws.database.username, environment, kafka.bootstrap.servers,
> aws.database.password, aws.database.database, aws.database.hostname,
> kafka.topic, aws.secret.password]' were supplied but are not used yet.
>
> 14:48:34,413 INFO org.apache.kafka.common.utils.AppInfoParser
> [] - Kafka version: 3.4.0
> 14:48:34,414 INFO org.apache.kafka.common.utils.AppInfoParser
> [] - Kafka commitId: 2e1947d240607d53
> 14:48:34,414 INFO org.apache.kafka.common.utils.AppInfoParser
> [] - Kafka startTimeMs: 1751269714413
> 14:48:34,427 INFO
> org.apache.flink.connector.base.source.reader.fetcher.SplitFetcher [] -
> Starting split fetcher 0
> 14:48:34,436 INFO org.apache.kafka.clients.consumer.KafkaConsumer
> [] - [Consumer clientId=flink-dev-group-stock-consumer-4,
> groupId=flink-dev-group-stock-consumer] Assigned to partition(s):
> dev-stock-topic-0
> 14:48:34,444 INFO
> org.apache.kafka.clients.consumer.internals.SubscriptionState [] -
> [Consumer clientId=flink-dev-group-stock-consumer-4,
> groupId=flink-dev-group-stock-consumer] Seeking to earliest offset of
> partition dev-stock-topic-0
> 14:48:34,470 INFO org.apache.kafka.clients.Metadata
> [] - [Consumer clientId=flink-dev-group-stock-consumer-4,
> groupId=flink-dev-group-stock-consumer] Resetting the last seen epoch of
> partition dev-stock-topic-0 to 0 since the associated topicId changed from
> null to jKk4sUaiRfSsg8h4GfqpbQ
> 14:48:34,471 INFO org.apache.kafka.clients.Metadata
> [] - [Consumer clientId=flink-dev-group-stock-consumer-4,
> groupId=flink-dev-group-stock-consumer] Cluster ID: MkU3OEVBNTcwNTJENDM2Qk
> 14:48:34,491 INFO
> org.apache.kafka.clients.consumer.internals.SubscriptionState [] -
> [Consumer clientId=flink-dev-group-stock-consumer-4,
> groupId=flink-dev-group-stock-consumer] Resetting offset for partition
> dev-stock-topic-0 to position FetchPosition{offset=0,
> offsetEpoch=Optional.empty,
> currentLeader=LeaderAndEpoch{leader=Optional[localhost:9092 (id: 1 rack:
> null)], epoch=0}}.
*Could you help me address the issue?*
Because I assigned the event_time and watermark, I print the output and the
timestamp is there. But it is failed to group by window_start and
window_end.
Dmitri Yanno Mahayana
Mail: dmitri.mahay...@gmail.com
Phone: +6281314435818
