Watermark (Flink : 2.0-SNAPSHOT API)

java.lang.Object
- org.apache.flink.api.common.eventtime.Watermark

All Implemented Interfaces:

Serializable
```
@Public
public final class Watermark
extends Object
implements Serializable
```
Watermarks are the progress indicators in the data streams. A watermark signifies that no events with a timestamp smaller or equal to the watermark's time will occur after the water. A watermark with timestamp T indicates that the stream's event time has progressed to time T.
Watermarks are created at the sources and propagate through the streams and operators.
In some cases a watermark is only a heuristic, meaning some events with a lower timestamp may still follow. In that case, it is up to the logic of the operators to decide what to do with the "late events". Operators can for example ignore these late events, route them to a different stream, or send update to their previously emitted results.
When a source reaches the end of the input, it emits a final watermark with timestamp Long.MAX_VALUE, indicating the "end of time".
Note: A stream's time starts with a watermark of Long.MIN_VALUE. That means that all records in the stream with a timestamp of Long.MIN_VALUE are immediately late.

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field Description

static Watermark MAX_WATERMARK
The watermark that signifies end-of-event-time.

Constructor Summary

Constructors
Constructor Description

Watermark(long timestamp)
Creates a new watermark with the given timestamp in milliseconds.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`equals(Object o)`
`String`	`getFormattedTimestamp()`	Formats the timestamp of this watermark, assuming it is a millisecond timestamp.
`long`	`getTimestamp()`	Returns the timestamp associated with this Watermark.
`int`	`hashCode()`
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - MAX_WATERMARK
```
public static final Watermark MAX_WATERMARK
```
    The watermark that signifies end-of-event-time.
- Constructor Detail
  - Watermark
```
public Watermark(long timestamp)
```
    Creates a new watermark with the given timestamp in milliseconds.
- Method Detail
  - getTimestamp
```
public long getTimestamp()
```
    Returns the timestamp associated with this Watermark.
  - getFormattedTimestamp
```
public String getFormattedTimestamp()
```
    Formats the timestamp of this watermark, assuming it is a millisecond timestamp. The returned format is "yyyy-MM-dd HH:mm:ss.SSS".
  - equals
```
public boolean equals(Object o)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object