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https://issues.apache.org/jira/browse/CALCITE-2555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16614543#comment-16614543
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Zoltan Haindrich commented on CALCITE-2555:
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It's great that the patch also addresses {{null > f\(x\)}} cases as well!
But I would like to note that I think there might be some issue with the
current patch because it calls {{simplify_}} from {{simplifyStrong()}}
* every node in the tree will be probably visited at least twice after this
change; because simplifyStrong will run an extra visit on the child nodes - and
the simplifyX method which supposed to simplify it, will do another run...which
will result in {{2**depth}} visits on every node
** this problem kinda takes me back to my earlier idea: that somehow visited
nodes should be tracked...because as we make it more more smarter; the
performance will eventually degrade...tracking would easily handle this problem
as well
* I didn't know about the Strong (I really like it by the way) - but I don't
think its needed in this case: I feel that adding some logic to
{{simplifyComparision}} would be better; because there is already a strategic
pattern in this class...the {{simpifyStrong()}} call I think a little bit
breaks that pattern.
> RexSimplify: >=(true, null) could be simplified to null
> -------------------------------------------------------
>
> Key: CALCITE-2555
> URL: https://issues.apache.org/jira/browse/CALCITE-2555
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.17.0
> Reporter: Vladimir Sitnikov
> Assignee: Julian Hyde
> Priority: Major
> Labels: newbie
>
> {code:java}
> @Test public void simplifyComparisonWithNull() {
> checkSimplify2(ge(trueLiteral, falseLiteral), "true", "true");
> checkSimplify2(ge(trueLiteral, nullBool), "null", "false");
> checkSimplify2(ge(nullBool, nullBool), "null", "false");
> }
> {code}
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