How to resolve error "Rowtime timestamp is null" in flink server - apache-flink

Question

I am trying to run some code in flink server but unable to
Below is my code
DataStream<UserInfo> keyedStream = executionEnvironment
.addSource(new UserDataSource());
keyedStream.assignTimestampsAndWatermarks(new MessageWaterEmitter());
tableEnv.registerDataStream("test", keyedStream, "userId,ticks,startime.rowtime");
Table table = tableEnv
.sqlQuery(
"SELECT userId,COUNT(userId) as ticks,TUMBLE_END(startime,INTERVAL '5' SECOND) as startime FROM test "
+ "GROUP BY TUMBLE(startime,INTERVAL '5' SECOND),userId");
DataStream<Row> userInfoDataStream = tableEnv.toRetractStream(table, Row.class)
.filter(new FilterFunction<Tuple2<Boolean, Row>>() {
#Override
public boolean filter(Tuple2<Boolean, Row> booleanUserInfoTuple2) throws Exception {
return booleanUserInfoTuple2.f0;
}
}).map(new MapFunction<Tuple2<Boolean, Row>, Row>() {
#Override
public Row map(Tuple2<Boolean, Row> booleanUserInfoTuple2) throws Exception {
return booleanUserInfoTuple2.f1;
}
});
JdbcSink sink = new JdbcSink();
userInfoDataStream.addSink(sink);
Below is the error am getting
java.lang.RuntimeException: Rowtime timestamp is null. Please make sure that a proper TimestampAssigner is defined and the stream environment uses the EventTime time characteristic.
at DataStreamSourceConversion$651.processElement(Unknown Source)
at org.apache.flink.table.runtime.CRowOutputProcessRunner.processElement(CRowOutputProcessRunner.scala:70)
at org.apache.flink.streaming.api.operators.ProcessOperator.processElement(ProcessOperator.java:66)
at org.apache.flink.streaming.runtime.tasks.OperatorChain$CopyingChainingOutput.pushToOperator(OperatorChain.java:637)
at org.apache.flink.streaming.runtime.tasks.OperatorChain$CopyingChainingOutput.collect(OperatorChain.java:612)
at org.apache.flink.streaming.runtime.tasks.OperatorChain$CopyingChainingOutput.collect(OperatorChain.java:592)
at org.apache.flink.streaming.runtime.tasks.OperatorChain$BroadcastingOutputCollector.collect(OperatorChain.java:707)
at org.apache.flink.streaming.runtime.tasks.OperatorChain$BroadcastingOutputCollector.collect(OperatorChain.java:660)
at org.apache.flink.streaming.api.operators.AbstractStreamOperator$CountingOutput.collect(AbstractStreamOperator.java:727)
at org.apache.flink.streaming.api.operators.AbstractStreamOperator$CountingOutput.collect(AbstractStreamOperator.java:705)
at org.apache.flink.streaming.api.operators.StreamSourceContexts$ManualWatermarkContext.processAndCollect(StreamSourceContexts.java:305)
at org.apache.flink.streaming.api.operators.StreamSourceContexts$WatermarkContext.collect(StreamSourceContexts.java:394)
at flink.source.UserDataSource.run(UserDataSource.java:20)
at org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:100)
at org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:63)
at org.apache.flink.streaming.runtime.tasks.SourceStreamTask$LegacySourceFunctionThread.run(SourceStreamTask.java:208)
can any body help me with this problem? thank you in advance

Answer 1

The root cause of this problem is that while you are calling assignTimestampsAndWatermarks on keyedStream, you aren't doing anything with the result of this call. If you rework the code like this, it will work:
DataStream<UserInfo> keyedStream = executionEnvironment
.addSource(new UserDataSource())
.assignTimestampsAndWatermarks(new MessageWaterEmitter());
tableEnv.registerDataStream("test", keyedStream, "userId,ticks,startime.rowtime");
Calling assignTimestampsAndWatermarks on a stream doesn't modify that stream, but instead returns a new stream that has timestamps and watermarks.
This could also be fixed this like, which might be a bit clearer as to what is going on:
DataStream<UserInfo> streamWithTSandWMs = keyedStream
.assignTimestampsAndWatermarks(new MessageWaterEmitter());
tableEnv.registerDataStream("test", streamWithTSandWMs, "userId,ticks,startime.rowtime");