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https://issues.apache.org/jira/browse/CALCITE-6532?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Adam Kennedy closed CALCITE-6532.
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Resolution: Duplicate
> Postgres RANDOM() is not flagged as non-deterministic
> -----------------------------------------------------
>
> Key: CALCITE-6532
> URL: https://issues.apache.org/jira/browse/CALCITE-6532
> Project: Calcite
> Issue Type: Bug
> Reporter: Adam Kennedy
> Priority: Major
>
> Putting aside the question of whether the default Calcite RAND can be
> deterministic (when used with a seed) etc, it is most certainly the case that
> the Postgres RANDOM() function is not deterministic.
> The following should return two different values.
> SELECT RANDOM(), RANDOM()
> In Calcite, currently it will return the same value twice as
> RexProgramBuilder deduplicates them to a single invocation (incorrectly).
> This bug does not address the behavior of RexProgram, as there are separate
> issues for the problem of RexProgram not obeying isDeterministic = false. But
> were that bug to be fixed, it would be irrelevant to the SELECT RANDOM(),
> RANDOM() problem as it stands, because a RexProgramBuilder that obey'ed
> determinism wouldn't see RANDOM() as deterministic anyway.
> Since RANDOM() is very new, and doesn't impact default Calcite use cases, I
> propose that we can also make non-deterministic RANDOM() a trial run for a
> later change of RAND() to non-deterministic.
> It's not entirely clear to me what the semantic intent of isDynamic
> originally was, I had assumed it was related to functions that need to reach
> outside the context of the query to read from the environment, and that as a
> side effect they should not be cached.
>
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