[4/5] flink git commit: [FLINK-7568] Add note about start/end timestamps in window doc

[al...@apache.org]

[FLINK-7568] Add note about start/end timestamps in window doc


Project: http://git-wip-us.apache.org/repos/asf/flink/repo
Commit: http://git-wip-us.apache.org/repos/asf/flink/commit/7d9e3bf8
Tree: http://git-wip-us.apache.org/repos/asf/flink/tree/7d9e3bf8
Diff: http://git-wip-us.apache.org/repos/asf/flink/diff/7d9e3bf8

Branch: refs/heads/master
Commit: 7d9e3bf8bc606fb4ac28a17f26df476f86d20c3e
Parents: f35f2d6
Author: Aljoscha Krettek <al...@gmail.com>
Authored: Fri Sep 1 13:45:01 2017 +0200
Committer: Aljoscha Krettek <al...@gmail.com>
Committed: Tue Sep 5 17:33:47 2017 +0200

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 docs/dev/stream/operators/windows.md | 5 +++++
 1 file changed, 5 insertions(+)
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http://git-wip-us.apache.org/repos/asf/flink/blob/7d9e3bf8/docs/dev/stream/operators/windows.md
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diff --git a/docs/dev/stream/operators/windows.md b/docs/dev/stream/operators/windows.md
index 1bd6dd9..85a6630 100644
--- a/docs/dev/stream/operators/windows.md
+++ b/docs/dev/stream/operators/windows.md
@@ -111,6 +111,11 @@ windows) assign elements to windows based on time, which can either be processin
 time. Please take a look at our section on [event time]({{ site.baseurl }}/dev/event_time.html) to learn
 about the difference between processing time and event time and how timestamps and watermarks are generated.
 
+Time-based windows have a *start timestamp* (inclusive) and an *end timestamp* (exclusive)
+that together describe the size of the window. In code, Flink uses `TimeWindow` when working with
+time-based windows which has methods for querying the start- and end-timestamp and also an
+additional method `maxTimestamp()` that returns the largest allowed timestamp for a given windows.
+
 In the following, we show how Flink's pre-defined window assigners work and how they are used
 in a DataStream program. The following figures visualize the workings of each assigner. The purple circles
 represent elements of the stream, which are partitioned by some key (in this case *user 1*, *user 2* and *user 3*).