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https://issues.apache.org/jira/browse/FLINK-15602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17016512#comment-17016512
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Zhenghua Gao commented on FLINK-15602:
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Hi [~dwysakowicz] [~tiwalter] I investigated the behavior of popular DBMS and
found: PostgreSQL DO NOT pad '0' and Oracle/MS SQL pad '0' (MYSQL would pad '0'
for TIMESTAMP type and not pad '0' for DATETIME type). And, hive/spark would
not pad '0' too.
What's your opinion about the padding behavior?
> 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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