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Posted to issues@flink.apache.org by "Aljoscha Krettek (JIRA)" <ji...@apache.org> on 2019/01/30 08:13:00 UTC
[jira] [Closed] (FLINK-11326) Allow negative offsets in window
assigners
[ https://issues.apache.org/jira/browse/FLINK-11326?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Aljoscha Krettek closed FLINK-11326.
------------------------------------
Resolution: Fixed
Fix Version/s: 1.8.0
Implemented in
master: 53044a08236a6b3a34199f5bd65187fad9014e20
> Allow negative offsets in window assigners
> ------------------------------------------
>
> Key: FLINK-11326
> URL: https://issues.apache.org/jira/browse/FLINK-11326
> Project: Flink
> Issue Type: Bug
> Components: Streaming
> Affects Versions: 1.6.3, 1.7.1
> Reporter: TANG Wen-hui
> Assignee: Kezhu Wang
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.8.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> 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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