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https://issues.apache.org/jira/browse/CALCITE-2438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16571208#comment-16571208
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Vladimir Sitnikov commented on CALCITE-2438:
--------------------------------------------
{quote}And I also think we can add some more operator case to the
RexCall#isAlwaysNull,just like this:
{quote}
As you might see, I had [similar approach a couple of days
ago|https://github.com/apache/calcite/compare/master...980f491323fcf61f5c966120870b3442cae41c23#diff-66bc135d44f8eb4d99a8882cd740c654R158],
however I think placing more logic into {{RexCall.isAlways*}} does not really
help, so I removed extra bits for now.
The case you show would be handled by {{is not null}} simplifications in
{{RexSimplify}}, and it makes no reason to duplicate that efforts (neither
makes sense to introduce new bugs!).
Consider the following expression:
{noformat}
$0: nullable int;
($0 is null) AND ($0=42)
{noformat}
None of the implementations in {{RexCall.isAlwaysNull}} would deduce that the
expression is always null yet RexSimplify would fold that.
For instance, current implementation of RexSimplify folds {{$0 is null AND
$0=42}} expression into {{IS TRUE(false)}}
Note: current implementation is able to fold {{IS TRUE(false)}} into {{false}}
yet it somehow fails to make both optimizations in one simplify call (it is
related to my #1 above)
> RexCall#isAlwaysTrue return incorrect result
> ---------------------------------------------
>
> Key: CALCITE-2438
> URL: https://issues.apache.org/jira/browse/CALCITE-2438
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.17.0
> Reporter: pengzhiwei
> Assignee: Julian Hyde
> Priority: Critical
> Attachments: 屏幕快照 2018-08-02 下午7.26.20.png, 屏幕快照 2018-08-02
> 下午7.34.26.png
>
>
> In the expression as followed:
> {code:java}
> ((sal IS NULL) IS NOT NULL) IS FALSE
> {code}
> The RexCall#isAlwaysTrue return true,however the correct answer is false.
> I find the reason is that there is a wrong logic in the isAlwaysTrue,when
> getKind() is IS_NOT_FALSE、IS_FALSE and IS_NOT_FALSE :
> !屏幕快照 2018-08-02 下午7.34.26.png!
> Can you have a check for me,thanks!
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