fsk119 opened a new pull request #14689:
URL: https://github.com/apache/flink/pull/14689
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## What is the purpose of the change
*The reason why the test fails is the records in the same partition are
out-of-order. I print the partition-id and offset in the partition.*
```
partition-0
<102,Greg,Berlin,BERLIN,2020-08-15T00:00:03,0,0>
<103,Richard,Berlin,BERLIN,2020-08-16T00:01:05,0,1>
<103,Richard,London,LONDON,2020-08-16T01:01:05,0,2>
<105,Tim,Shenzhen,SHENZHEN,2020-08-16T00:06,0,3>
<105,Tim,Hongkong,HONGKONG,2020-08-16T01:06,0,4>
partition-1
<100,Bob,Beijing,BEIJING,2020-08-15T00:00:01,1,0>
<101,Alice,Shanghai,SHANGHAI,2020-08-15T00:00:02,1,1>
<101,Alice,Wuhan,WUHAN,2020-08-16T00:02,1,2>
<101,Alice,Hangzhou,HANGZHOU,2020-08-16T01:04:05,1,3>
<104,Tomato,Hongkong,HONGKONG,2020-08-16T00:05:05,1,4>
<104,Tomato,Shenzhen,SHENZHEN,2020-08-16T01:05:05,1,5>
```
In the test, the expected record is
`<10004,104,2020-08-16T00:05:06,Tomato,HONGKONG,2020-08-16T00:05:05>
` but the actual record is `<10004,104,2020-08-16T00:05:06,null,null,null>`.
It may be the left stream record `<10004,104,2020-08-16T00:05:06>` arrives
before the record `<104,Tomato,Hongkong,HONGKONG,2020-08-16T00:05:05,1,4>
` in the right stream. When the left stream arrives, it finds the watermark
is at timestamp `2020-08-16T01:04:05` in the right stream, which means the
records before `2020-08-16T01:04:05` have arrived and emits itself.
Therefore, we should adjust the order in the partition or watermark
strategy. Here we just adjust order for convenience. The new order in the
partition follows.
```
<102,Greg,Berlin,BERLIN,2020-08-15T00:00:03,0,0>
<103,Richard,Berlin,BERLIN,2020-08-16T00:01:05,0,1>
<105,Tim,Shenzhen,SHENZHEN,2020-08-16T00:06,0,2>
<103,Richard,London,LONDON,2020-08-16T01:01:05,0,3>
<105,Tim,Hongkong,HONGKONG,2020-08-16T01:06,0,4>
<100,Bob,Beijing,BEIJING,2020-08-15T00:00:01,1,0>
<101,Alice,Shanghai,SHANGHAI,2020-08-15T00:00:02,1,1>
<101,Alice,Wuhan,WUHAN,2020-08-16T00:02,1,2>
<104,Tomato,Hongkong,HONGKONG,2020-08-16T00:05:05,1,3>
<101,Alice,Hangzhou,HANGZHOU,2020-08-16T01:04:05,1,4>
<104,Tomato,Shenzhen,SHENZHEN,2020-08-16T01:05:05,1,5>
```
## Brief change log
- *Reorder the records in the partition*
## Documentation
- Does this pull request introduce a new feature? (yes / **no**)
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