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https://issues.apache.org/jira/browse/CALCITE-987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15030156#comment-15030156
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Jesus Camacho Rodriguez commented on CALCITE-987:
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[~pxiong], I checked the new patch, LGTM, thanks!
I would just change slightly the following block for Union:
{noformat}
if (partialRowCount == null) {
continue;
}
{noformat}
so it returns null in case it cannot get the count for one of the inputs. If
you agree, I will just change it when I check in the patch.
> 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
> Reporter: Pengcheng Xiong
> Assignee: Pengcheng Xiong
> Attachments: CALCITE-987.01.patch, CALCITE-987.02.patch,
> CALCITE-987.03.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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