Github user snuyanzin commented on the issue:
https://github.com/apache/flink/pull/6007
@twalthr thank you for your comment but could you please clarify this
> Can you add some documentation to sqlApi.md such that users know about
the semantics?
1. Am I right that you mean `docs/dev/table/sql.md`?
2. Currently I see the general explanation of extract and reserved words
where DOW already specified.
From this point of view I do not see what could be updated right now. At
the same time I have a proposal to go to the similar way as Calcite does.
[Here](https://calcite.apache.org/docs/reference.html) there is a link to their
functions including date/time. Among extract they also have synonyms e.g.
>MONTH(date) | Equivalent to EXTRACT(MONTH FROM date). Returns an integer
between 1 and 12.
>WEEK(date) | Equivalent to EXTRACT(WEEK FROM date). Returns an integer
between 1 and 53.
>DAYOFYEAR(date) | Equivalent to EXTRACT(DOY FROM date). Returns an integer
between 1 and 366.
and etc.
So I suggest to introduce the same synonyms in flink (just via usage of
existing in Calcite) and organize documentation for them in a similar way
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