[FLINK-13433][table-planner-blink] Do not fetch data from LookupableTableSource if the JoinKey in left side of LookupJoin contains null value.

[beyond1920]

What is the purpose of the change

For LookupJoin, if joinKey in left side of a LeftOuterJoin/InnerJoin contains null values, there is no need to fetch data from LookupableTableSource.
However, we don't shortcut the fetch function under the case at present, the correctness of results depends on the TableFunction implementation of each LookupableTableSource.

Brief change log

• correct the behavior of LookupJoin where lookupKeys contains null.
• Add more testcases.

Verifying this change

testcases

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable

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[beyond1920]

cc @wuchong @lincoln-lil

[flinkbot]

CI report:

• bb70e45 : FAILURE Build
• 4f96a18 : FAILURE Build
• a915ad9 : FAILURE Build
• 3e6a308 : FAILURE Build
• 5958000 : SUCCESS Build
• 5d22079 : CANCELED Build
• a10620b : SUCCESS Build

[lincoln-lil]

Looks good! I've left some minor comments, btw, would it be better to parameterize the synchronous/asynchronous mode for the it case ?

[JingsongLi]

I am interested to sql: SELECT T.id, T.len, T.content, D.name FROM T JOIN userTable for system_time as of T.proctime AS D ON T.id = D.id OR (T.id is null and D.id is null).
Does it work?

[beyond1920]

@JingsongLi At first glance, I guess the query is not supported.
However, after run it actually, The query could be executed, but results in error outputs.
Because LookupJoin does not take filterNulls (which says k=v or k is not distinct from v) into consideration.

Good catch, I will looks into the problem.

[wuchong]

Thanks @beyond1920 , could you also update InMemoryAsyncLookupFunction#eval and InMemoryLookupFunction#eval to throw exception when one of the argument is null?

[beyond1920]

@wuchong

could you also update InMemoryAsyncLookupFunction#eval and InMemoryLookupFunction#eval to throw exception when one of the argument is null？

Hi, JarkWu, InMemoryAsyncLookupFunction and InMemoryLookupFunction lookup records with null value on the lookup key field when argument contains null, which complies with the contract mentioned in https://github.com/apache/flink/pull/9335/files, I think the behavior is also reasonable.

[wuchong]

I agree with you @beyond1920 , however, I want to have some test to cover we didn't push any nulls into LookupFunction. That's why I want to add such check in InMemoryLookupFunction. We can remove the check when we support push is null into LookupFunction?

[beyond1920]

@wuchong , Ok

[wuchong]

Thanks @beyond1920 , looks good to me now.

[KurtYoung]

BTW, could you also open a jira for empty key for hbase lookup function? hbase forbidden empty row key.

[beyond1920]

@KurtYoung The hbase lookup function is updated in #9335.