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https://issues.apache.org/jira/browse/CALCITE-4215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17189794#comment-17189794
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Danny Chen commented on CALCITE-4215:
-------------------------------------
Just like you said
"At the end of the day, if the collation is not known, it is unlikely we could
figure it out. Then it is indistinguishable from *table is completely
unsorted*".
It doesn't make much sense to distinguish between known and empty, if we return
nulls, all the codes that query these metadata need to identify the difference,
which complicates logic but gains little. From this point of view, adding
enumerations doesn't really resolve the problem.
> Ensure org.apache.calcite.schema.Statistic uses null vs emptyList
> appropriately
> -------------------------------------------------------------------------------
>
> Key: CALCITE-4215
> URL: https://issues.apache.org/jira/browse/CALCITE-4215
> Project: Calcite
> Issue Type: Sub-task
> Components: core
> Affects Versions: 1.25.0
> Reporter: Vladimir Sitnikov
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> null: statistic is *not* *known*
> emptyList: statistic is *known*, and the value is *empty* (e.g. no unique
> keys in the table)
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