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From "buptljy (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-7205) Add UUID supported in TableAPI/SQL
Date Sat, 21 Jul 2018 14:57:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-7205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16551722#comment-16551722
] 

buptljy commented on FLINK-7205:
--------------------------------

[~fhueske]

I find that we cannot test _*UUID*_ function in *_ScalarFunctionsTest_* because we're not
able to offer an expected UUID...

In my opinion, we can test the _*UUID*_ **in another way, like testing the length of the
string and the position of the seperator "-", though it does not look very appropriate.

> Add UUID supported in TableAPI/SQL
> ----------------------------------
>
>                 Key: FLINK-7205
>                 URL: https://issues.apache.org/jira/browse/FLINK-7205
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API &amp; SQL
>    Affects Versions: 1.4.0
>            Reporter: sunjincheng
>            Assignee: buptljy
>            Priority: Major
>
> UUID() returns a value that conforms to UUID version 1 as described in RFC 4122. The
value is a 128-bit number represented as a utf8 string of five hexadecimal numbers in aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee
format:
> The first three numbers are generated from the low, middle, and high parts of a timestamp.
The high part also includes the UUID version number.
> The fourth number preserves temporal uniqueness in case the timestamp value loses monotonicity
(for example, due to daylight saving time).
> The fifth number is an IEEE 802 node number that provides spatial uniqueness. A random
number is substituted if the latter is not available (for example, because the host device
has no Ethernet card, or it is unknown how to find the hardware address of an interface on
the host operating system). In this case, spatial uniqueness cannot be guaranteed. Nevertheless,
a collision should have very low probability.
> See: [RFC 4122: http://www.ietf.org/rfc/rfc4122.txt|http://www.ietf.org/rfc/rfc4122.txt]
> See detailed semantics:
>    MySql: [https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_uuid|https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_uuid]
> Welcome anybody feedback -:).



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