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https://issues.apache.org/jira/browse/CALCITE-987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15034250#comment-15034250
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Jesus Camacho Rodriguez commented on CALCITE-987:
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[~julianhyde], thanks, and sorry for checking this in without checking it too
exhaustively. A couple of comments:
- In estimateJoinedRows, a {{not null}} check should be done for {{Double
left}} and {{Double right}} too.
- I agree with [~pxiong] that at least in RelMdMaxRowCount, as we are not
returning an estimate, it would be better to return null if we cannot get the
row count from all children?
> Push limit 0 will result in an infinite loop
> --------------------------------------------
>
> Key: CALCITE-987
> URL: https://issues.apache.org/jira/browse/CALCITE-987
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.5.0
> Reporter: Pengcheng Xiong
> Assignee: Pengcheng Xiong
> Fix For: 1.6.0
>
> Attachments: CALCITE-987.01.patch, CALCITE-987.02.patch,
> CALCITE-987.03.patch, CALCITE-987.04.patch
>
>
> We use "checkInputForCollationAndLimit" in RelMdUtil.java to check the input
> #rows. However, it calls RelMetadataQuery.getRowCount which will validate the
> #rows. The validation will change #row=0 to #row=1. This will result in an
> infinite loop to push limit. The affected rules include
> SortUnionTransposeRule and any Sort***TransposeRules that call
> checkInputForCollationAndLimit.
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