[jira] [Commented] (FLINK-15602) Blink planner does not respect the precision when casting timestamp to varchar

["Dawid Wysakowicz (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-15602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17015940#comment-17015940 ] 

Dawid Wysakowicz commented on FLINK-15602:
------------------------------------------

cc [~jark] [~docete]

> Blink planner does not respect the precision when casting timestamp to varchar
> ------------------------------------------------------------------------------
>
>                 Key: FLINK-15602
>                 URL: https://issues.apache.org/jira/browse/FLINK-15602
>             Project: Flink
>          Issue Type: Bug
>          Components: Table SQL / Planner
>    Affects Versions: 1.10.0
>            Reporter: Dawid Wysakowicz
>            Priority: Blocker
>             Fix For: 1.10.0
>
>
> According to SQL 2011 Part 2 Section 6.13 General Rules 11) d)
> {quote}
> If SD is a datetime data type or an interval data type then let Y be the shortest character string that
> conforms to the definition of <literal> in Subclause 5.3, “<literal>”, and such that the interpreted value
> of Y is SV and the interpreted precision of Y is the precision of SD.
> {quote}
> That means:
> {code}
> select cast(cast(TO_TIMESTAMP('2014-07-02 06:14:00', 'YYYY-MM-DD HH24:mm:SS') as TIMESTAMP(0)) as VARCHAR(256)) from ...;
> // should produce
> // 2014-07-02 06:14:00
> select cast(cast(TO_TIMESTAMP('2014-07-02 06:14:00', 'YYYY-MM-DD HH24:mm:SS') as TIMESTAMP(3)) as VARCHAR(256)) from ...;
> // should produce
> // 2014-07-02 06:14:00.000
> select cast(cast(TO_TIMESTAMP('2014-07-02 06:14:00', 'YYYY-MM-DD HH24:mm:SS') as TIMESTAMP(9)) as VARCHAR(256)) from ...;
> // should produce
> // 2014-07-02 06:14:00.000000000
> {code}
> One possible solution would be to propagate the precision in {{org.apache.flink.table.planner.codegen.calls.ScalarOperatorGens#localTimeToStringCode}}. If I am not mistaken this problem was introduced in [FLINK-14599]



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