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🗓️ 17012025 1959
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flink_side_outputs

Use Cases​

  • Reporting
    • Exceptions
    • Malformed events
    • Late events
    • Operational alerts, such as timed-out connections to external services
  • Implement n-way split of a stream

Example​

private static final OutputTag<TaxiFare> lateFares = new OutputTag<TaxiFare>("lateFares") {};
if (eventTime <= timerService.currentWatermark()) {
    // This event is late; its window has already been triggered.
    ctx.output(lateFares, fare);
} else {
    . . .
}
// compute the sum of the tips per hour for each driver
SingleOutputStreamOperator hourlyTips = fares
        .keyBy((TaxiFare fare) -> fare.driverId)
        .process(new PseudoWindow(Time.hours(1)));

hourlyTips.getSideOutput(lateFares).print();
NOTE

Alternatively, you can use two OutputTags with the same name to refer to the same side output, but if you do, they must have the same type

References