[FLINK-11711][table-planner-blink] Add table and column stats

[godfreyhe]

What is the purpose of the change

This commit defines the structure of table and column stats which provide statistics for Calcite cost model.

Brief change log

• add TableStats, ColumnStats and FlinkStatistic

Verifying this change

This change added tests and can be verified as follows:

• Added unit tests for TableStats, ColumnStats and FlinkStatistic

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: (yes / no / don't know)
• 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? (JavaDocs)

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Automated Checks

Last check on commit 19886c4 (Wed Apr 15 11:36:34 UTC 2020)

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• ❓ 1. The [description] looks good.
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• ❓ 3. Needs [attention] from.
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• ❓ 5. Overall code [quality] is good.

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[KurtYoung]

Not sure what does "a correct value" mean. I think given a mathematical expression should be clear and sufficient, like "actual max value <= max"

[KurtYoung]

LGTM

[KurtYoung]

@flinkbot approve all

[KurtYoung]

@flinkbot disapprove all

[KurtYoung]

Postpone this after #7642 gets merged.

[twalthr]

#7642 has been merged. One comment about the package location of TableStats and ColumnStats: Once we expose those classes through table sources, we should think about moving them to another package within flink-table-common. Maybe org.apache.flink.table.statistics?

[godfreyhe]

see FLINK-11516 & FLINK-14789