TANG Wen-hui created FLINK-11326:
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Summary: Using offsets to adjust windows to timezones UTC-8 throws IllegalArgumentException
Key: FLINK-11326
URL:
https://issues.apache.org/jira/browse/FLINK-11326 Project: Flink
Issue Type: Bug
Components: Streaming
Affects Versions: 1.6.3
Reporter: TANG Wen-hui
According to comments, we can use offset to adjust windows to timezones other than UTC-0. For example, in China you would have to specify an offset of {{Time.hours(-8)}}.
{code:java}
/**
* Creates a new {@code TumblingEventTimeWindows} {@link WindowAssigner} that assigns
* elements to time windows based on the element timestamp and offset.
*
* <p>For example, if you want window a stream by hour,but window begins at the 15th minutes
* of each hour, you can use {@code of(Time.hours(1),Time.minutes(15))},then you will get
* time windows start at 0:15:00,1:15:00,2:15:00,etc.
*
* <p>Rather than that,if you are living in somewhere which is not using UTC±00:00 time,
* such as China which is using UTC+08:00,and you want a time window with size of one day,
* and window begins at every 00:00:00 of local time,you may use {@code of(Time.days(1),Time.hours(-8))}.
* The parameter of offset is {@code Time.hours(-8))} since UTC+08:00 is 8 hours earlier than UTC time.
*
* @param size The size of the generated windows.
* @param offset The offset which window start would be shifted by.
* @return The time policy.
*/
public static TumblingEventTimeWindows of(Time size, Time offset) {
return new TumblingEventTimeWindows(size.toMilliseconds(), offset.toMilliseconds());
}{code}
but when offset is smaller than zero, a IllegalArgumentException will be throwed.
{code:java}
protected TumblingEventTimeWindows(long size, long offset) {
if (offset < 0 || offset >= size) {
throw new IllegalArgumentException("TumblingEventTimeWindows parameters must satisfy 0 <= offset < size");
}
this.size = size;
this.offset = offset;
}{code}
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