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Posted to commits@flink.apache.org by da...@apache.org on 2020/09/09 12:46:09 UTC
[flink-training] branch master updated: [hotfix] output examples in
HourlyTips discussion should match actual output (#14)
This is an automated email from the ASF dual-hosted git repository.
danderson pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/flink-training.git
The following commit(s) were added to refs/heads/master by this push:
new 40fdc82 [hotfix] output examples in HourlyTips discussion should match actual output (#14)
40fdc82 is described below
commit 40fdc825ceff58f79dce8d5b98ea608339cc5644
Author: David Anderson <da...@alpinegizmo.com>
AuthorDate: Wed Sep 9 14:46:02 2020 +0200
[hotfix] output examples in HourlyTips discussion should match actual output (#14)
---
hourly-tips/DISCUSSION.md | 70 ++++++++++++++++++++++++-----------------------
1 file changed, 36 insertions(+), 34 deletions(-)
diff --git a/hourly-tips/DISCUSSION.md b/hourly-tips/DISCUSSION.md
index 6c9541a..888a015 100644
--- a/hourly-tips/DISCUSSION.md
+++ b/hourly-tips/DISCUSSION.md
@@ -76,21 +76,16 @@ to compute `hourlyTips`.
Having computed `hourlyTips`, it is a good idea to take a look at what this stream looks like. `hourlyTips.print()` yields something like this,
```
-1> (1357002000000,2013000019,1.0)
-1> (1357002000000,2013000036,6.4)
-1> (1357002000000,2013000027,15.4)
-1> (1357002000000,2013000071,1.0)
-1> (1357002000000,2013000105,3.65)
-1> (1357002000000,2013000110,1.8)
-1> (1357002000000,2013000237,0.0)
-1> (1357002000000,2013000580,0.0)
-1> (1357002000000,2013000968,0.0)
-1> (1357002000000,2013002242,2.0)
-1> (1357002000000,2013004131,0.0)
-1> (1357002000000,2013008339,0.0)
-3> (1357002000000,2013000026,5.45)
-3> (1357002000000,2013000009,2.0)
-1> (1357002000000,2013008305,0.0)
+2> (1577883600000,2013000185,33.0)
+4> (1577883600000,2013000108,14.0)
+3> (1577883600000,2013000087,14.0)
+1> (1577883600000,2013000036,23.0)
+4> (1577883600000,2013000072,13.0)
+2> (1577883600000,2013000041,28.0)
+3> (1577883600000,2013000123,33.0)
+4> (1577883600000,2013000188,18.0)
+1> (1577883600000,2013000098,23.0)
+2> (1577883600000,2013000047,13.0)
...
```
@@ -107,11 +102,12 @@ DataStream<Tuple3<Long, Long, Float>> hourlyMax = hourlyTips
which works just fine, producing this stream of results:
```
-1> (1357002000000,2013000493,54.45)
-2> (1357005600000,2013010467,64.53)
-3> (1357009200000,2013010589,104.75)
-4> (1357012800000,2013010182,150.0)
-1> (1357016400000,2013010182,90.0)
+3> (1577883600000,2013000089,76.0)
+4> (1577887200000,2013000197,71.0)
+1> (1577890800000,2013000118,83.0)
+2> (1577894400000,2013000119,81.0)
+3> (1577898000000,2013000195,73.0)
+4> (1577901600000,2013000072,123.0)
```
But, what if we were to do this, instead?
@@ -122,28 +118,34 @@ DataStream<Tuple3<Long, Long, Float>> hourlyMax = hourlyTips
.maxBy(2);
```
-This says to group the stream of `hourlyTips` by timestamp, and within each timestamp, find the maximum of the sum of the tips. That sounds like it is exactly what we want. And while this alternative does find the same results, there are a couple of reasons why it is not a very good solution.
+This says to group the stream of `hourlyTips` by timestamp, and within each timestamp, find the maximum of the sum of the tips.
+That sounds like it is exactly what we want. And while this alternative does find the same results,
+there are a couple of reasons why it is not a very good solution.
-First, instead of producing a single result at the end of each window, with this approach we get a stream that is continuously reporting the maximum achieved so far, for each key (i.e., each hour), which is an awkward way to consume the result if all you wanted was a single value for each hour.
+First, instead of producing a single result at the end of each window, with this approach we get a stream that is
+continuously reporting the maximum achieved so far, for each key (i.e., each hour), which is an awkward way to consume
+the result if all you wanted was a single value for each hour.
```
-3> (1357002000000,2013000019,1.0)
-3> (1357002000000,2013000036,6.4)
-3> (1357002000000,2013000027,15.4)
+1> (1577883600000,2013000108,14.0)
+1> (1577883600000,2013000108,14.0)
+1> (1577883600000,2013000188,18.0)
+1> (1577883600000,2013000188,18.0)
+1> (1577883600000,2013000188,18.0)
+1> (1577883600000,2013000034,36.0)
+1> (1577883600000,2013000183,70.0)
+1> (1577883600000,2013000183,70.0)
...
-3> (1357002000000,2013009336,25.0)
+1> (1577883600000,2013000152,73.0)
+1> (1577883600000,2013000152,73.0)
...
-3> (1357002000000,2013006686,38.26)
-...
-3> (1357002000000,2013005943,40.08)
-...
-3> (1357002000000,2013005747,51.8)
-...
-3> (1357002000000,2013000493,54.45)
+1> (1577883600000,2013000089,76.0)
...
```
-Second, Flink will be keeping in state the maximum seen so far for each key (each hour), forever. Flink has no idea that these keys are event-time timestamps, and that the watermarks could be used as an indicator of when this state can be cleared -- to get those semantics, we need to use windows.
+Second, Flink will be keeping in state the maximum seen so far for each key (each hour), forever.
+Flink has no idea that these keys are event-time timestamps, and that the watermarks could be used as
+an indicator of when this state can be cleared -- to get those semantics, we need to use windows.
-----