[FLINK-18731][table-planner-blink] Fix monotonicity logic of UNIX_TIMESTAMP & UUID functions

[godfreyhe]

What is the purpose of the change

UNIX_TIMESTAMP function has INCREASING monotonicity only if it has empty function arguments, else has NOT_MONOTONIC monotonicity

Brief change log

• Correct the monotonicity logic of UNIX_TIMESTAMP function in FlinkSqlOperatorTable

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

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• The S3 file system connector: (yes / no / don't know)

Documentation

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

[godfreyhe]

cc @wuchong

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CI report:

• 9bca4ec Azure: FAILURE Azure: FAILURE Azure: PENDING

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[wuchong]

1. Maybe we should also fix the isDeterministic. What do you think to have a specific UnixTimestampSqlFunction class? The logic stayed in FlinkSqlOperatorTable is quite verbose.
2. Maybe we should also fix UUID#getMonotonicity?
3. Is it possible to have a test to reproduce the problem?

[godfreyhe]

Thanks for the suggestion,

1. Maybe we should also fix the isDeterministic. What do you think to have a specific UnixTimestampSqlFunction class? The logic stayed in FlinkSqlOperatorTable is quite verbose.

we can't fix isDeterministic, because different from getMonotonicity(SqlOperatorBinding call), isDeterministic() knows nothing about operand count. One approach is we can split UNIX_TIMESTAMP into two different functions, but I think it's unnecessary.
If we only fix getMonotonicity, I trend to keep the logic in FlinkSqlOperatorTable.

2. Maybe we should also fix UUID#getMonotonicity?

good catch

3. Is it possible to have a test to reproduce the problem?

Tests have been added

[godfreyhe]

@flinkbot run azure

[wuchong]

LGTM.

[wuchong]

@flinkbot run azure

[godfreyhe]

my private azure is green https://dev.azure.com/godfreyhe/godfreyhe-flink/_build/results?buildId=74&view=results