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https://issues.apache.org/jira/browse/FLINK-29091?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Godfrey He closed FLINK-29091.
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Resolution: Fixed
Fixed in master: 4b15bc900eb60b1830bc406975ce974ad6050f98
> Fix the determinism declaration of the rand function to be consistent with
> current behavior
> -------------------------------------------------------------------------------------------
>
> Key: FLINK-29091
> URL: https://issues.apache.org/jira/browse/FLINK-29091
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / Planner
> Reporter: lincoln lee
> Assignee: lincoln lee
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.16.0
>
>
> RAND and RAND_INTEGER are declared as dynamic function (isDynamicFuntion
> returns true), as the declaration it should only evaluate once at query-level
> (not per record) for batch mode, FLINK-21713 did the similar fix for temporal
> functions.
> But current behavior is completely a non-deterministic function which
> evaluated per record for both batch and streaming mode, it's not a good
> choice to break current behavior, and the determinism of RAND function are
> also different across vendors:
> [1] evaluated at query-level though it is treated as non-deterministic
> function
> [https://docs.microsoft.com/en-us/sql/relational-databases/user-defined-functions/deterministic-and-nondeterministic-functions?view=sql-server-ver16#built-in-function-determinism|https://docs.microsoft.com/en-us/sql/relational-databases/user-defined-functions/deterministic-and-nondeterministic-functions?view=sql-server-ver16#built-in-function-determinism)]
> [2][ evaluated at row level:
> [https://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_rand]|https://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_rand)]
> [3] evaluated at row level if not specifies a seed, e.g.,
> DBMS_RANDOM.normal, DBMS_RANDOM.value(1,10)
> [https://docs.oracle.com/database/timesten-18.1/TTPLP/d_random.htm#TTPLP71231|https://docs.oracle.com/database/timesten-18.1/TTPLP/d_random.htm#TTPLP71231)]
> So just fix the determinism declaration of the rand function to be consistent
> with the current behavior and make it clear in the documentation.
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