[
https://issues.apache.org/jira/browse/FLINK-12714?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Wenshuai Hou updated FLINK-12714:
---------------------------------
Description:
hi flink team, i think the flink doc on how time windows are created and the
javadoc of related method is a little confusing. They give me the impression
that the window-start equals to the timestamp of the first event assigned to
that window, however the window-start is actually quantized by the windowSize,
see links below. Is this the intention or is this a mistake? If it's intended,
can we please leave a comment in flink doc somewhere to make this more clear? I
spent 5 hours wondering why my flink tests fail until i find that method.
Thanks
Wen
links:
================
The flink doc from here :
[https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#window-lifecycle]
> In a nutshell, a window is *created* as soon as the first element that should
> belong to this window arrives
the java doc of this method:
org.apache.flink.streaming.api.windowing.windows.TimeWindow#getWindowStartWithOffset
{code:java}
/**
* Method to get the window start for a timestamp.
*
* @param timestamp epoch millisecond to get the window start.
* @param offset The offset which window start would be shifted by.
* @param windowSize The size of the generated windows.
* @return window start
*/
public static long getWindowStartWithOffset(long timestamp, long offset, long
windowSize) {
{code}
was:
hi flink team, i think the flink doc on how time windows are created an the
javadoc of related method is a little confusing. They give me the impression
that the window-start equals to the timestamp of the first event assigned to
that window, however the window-start is actually quantized by the windowSize,
see links below. Is this the intention or is this a mistake? can we please
leave a comment in flink doc somewhere to make this more clear? I spent 5 hours
wondering why my flink tests fail until i find that method.
Thanks
Wen
links:
================
The flink doc from here :
[https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#window-lifecycle]
> In a nutshell, a window is *created* as soon as the first element that should
> belong to this window arrives
the java doc of this method:
org.apache.flink.streaming.api.windowing.windows.TimeWindow#getWindowStartWithOffset
{code:java}
/**
* Method to get the window start for a timestamp.
*
* @param timestamp epoch millisecond to get the window start.
* @param offset The offset which window start would be shifted by.
* @param windowSize The size of the generated windows.
* @return window start
*/
public static long getWindowStartWithOffset(long timestamp, long offset, long
windowSize) {
{code}
> confusion about flink time window TimeWindow#getWindowStartWithOffset
> ---------------------------------------------------------------------
>
> Key: FLINK-12714
> URL: https://issues.apache.org/jira/browse/FLINK-12714
> Project: Flink
> Issue Type: Improvement
> Components: flink-contrib
> Affects Versions: 1.8.0
> Reporter: Wenshuai Hou
> Priority: Minor
>
>
> hi flink team, i think the flink doc on how time windows are created and the
> javadoc of related method is a little confusing. They give me the impression
> that the window-start equals to the timestamp of the first event assigned to
> that window, however the window-start is actually quantized by the
> windowSize, see links below. Is this the intention or is this a mistake? If
> it's intended, can we please leave a comment in flink doc somewhere to make
> this more clear? I spent 5 hours wondering why my flink tests fail until i
> find that method.
>
> Thanks
> Wen
>
> links:
> ================
>
> The flink doc from here :
> [https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#window-lifecycle]
>
> > In a nutshell, a window is *created* as soon as the first element that
> > should belong to this window arrives
>
> the java doc of this method:
> org.apache.flink.streaming.api.windowing.windows.TimeWindow#getWindowStartWithOffset
>
>
> {code:java}
> /**
> * Method to get the window start for a timestamp.
> *
> * @param timestamp epoch millisecond to get the window start.
> * @param offset The offset which window start would be shifted by.
> * @param windowSize The size of the generated windows.
> * @return window start
> */
> public static long getWindowStartWithOffset(long timestamp, long offset, long
> windowSize) {
> {code}
>
>
>
>
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
