[jira] [Updated] (FLINK-29091) Fix the determinism declaration of the rand function to be consistent with current behavior

["lincoln lee (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-29091?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

lincoln lee updated FLINK-29091:
--------------------------------
    Summary: Fix the determinism declaration of the rand function to be consistent with current behavior  (was: Fix the determinism declaration of the rand function to be consistent with the current behavior)

> 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
>            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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