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https://issues.apache.org/jira/browse/CALCITE-7145?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18030330#comment-18030330
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Stamatis Zampetakis commented on CALCITE-7145:
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I admit that using the term constant for 10 / 0 is slightly abusive. Apart from
that since 10 / 0 has different behavior/results from one DBMS to another I
feel that it's safer to let {{IS [NOT] NULL (x / 0 )}} as is during
simplification so the proposal here and the respective PR makes sense to me.
Going further, I don't know of any DBMS that returns {{false}} for {{IS
NULL(10/0)}} so the current behavior of simplifier will be considered a bug
from most people.
For the historical part, the term "safe" was introduced by CALCITE-1413 to
protect against invalid simplifications mostly around conditional (CASE)
statements. The division operator is considered unsafe mostly due to the misc
semantics of division by zero.
> RexSimplify should not simplify IS NULL(10/0)
> ---------------------------------------------
>
> Key: CALCITE-7145
> URL: https://issues.apache.org/jira/browse/CALCITE-7145
> Project: Calcite
> Issue Type: Bug
> Reporter: Thomas Rebele
> Assignee: Thomas Rebele
> Priority: Major
> Labels: pull-request-available
>
> RexSimplify incorrectly simplifies {{IS NULL(10/0)}} to false and {{IS NOT
> NULL(10,0)}} to true
> In other DBMS it's either the inverse (sqlite, MySQL, MariaDB), or they throw
> an exception in both cases (Oracle, Postgres). The behavior was also
> mentioned in a comment on CALCITE-3368.
> Is it right that throwing an exception during query execution is the expected
> behavior according to the SQL standard?
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