[FLINK-20500][upsert-kafka] Fix temporal join test

[fsk119]

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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[leonardBang]

Thanks @fsk119 for the contribution, the change look good to me, the PR description is really good, it's great if we can add some note I in the code for readable consideration.

[leonardBang]

LGTM

[wuchong]

Great PR description and thanks for digging into it.

LGTM.