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https://issues.apache.org/jira/browse/CALCITE-783?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14621002#comment-14621002
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Julian Hyde commented on CALCITE-783:
-------------------------------------
Will do. By the way, there are a lot of spurious formatting changes in your
patch. You'll need to back these out. I'll keep your changes separate from mine
so it should be fairly easy for you to back out the formatting changes.
> Infer collation of Project using monotonicity
> ---------------------------------------------
>
> Key: CALCITE-783
> URL: https://issues.apache.org/jira/browse/CALCITE-783
> Project: Calcite
> Issue Type: Bug
> Components: core
> Reporter: Milinda Lakmal Pathirage
> Assignee: Julian Hyde
> Attachments: CALCITE-783-0.patch, CALCITE-783-1.patch
>
>
> Current implementation of RelMdCollation#project doesn't handle function
> expressions and because of that we loose any collation metadata related to
> monotonic expressions which can be useful for generating streaming query
> execution plans involving tumbling windows.
> Following is how current code looks like (RelMdCollation):
> 185: for (Ord<RexNode> project : Ord.zip(projects)) {
> 186: if (project.e instanceof RexInputRef) {
> 187: targets.put(((RexInputRef) project.e).getIndex(), project.i);
> 188: }
> 189: }
> We only handle projects of type RexInputRef. But to support monotonic
> expressions we should laso handle projects of type RexCall.
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