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https://issues.apache.org/jira/browse/CALCITE-5944?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17759235#comment-17759235
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Jiajun Xie commented on CALCITE-5944:
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Would anyone please review it?
> Add metadata for Sample
> -----------------------
>
> Key: CALCITE-5944
> URL: https://issues.apache.org/jira/browse/CALCITE-5944
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Jiajun Xie
> Assignee: Jiajun Xie
> Priority: Minor
> Labels: pull-request-available
>
> For the sql
> {code:java}
> select * from emp tablesample system(20) {code}
> `mq.getRowCount(rel)` is null, but we can return `inputRowCount * 0.2`.
>
> Some metadata need to be implemented.
> * RelMdAllPredicates
> * RelMdColumnOrigins
> * RelMdExpressionLineage
> * RelMdMaxRowCount
> * RelMdMinRowCount
> * RelMdPredicates
> * RelMdRowCount
> Some metadata have been implemented.
> * RelMdTableReferences
> * RelMdNodeTypes
> Some metadabata not need to be implemented.
> * RelMdColumnUniqueness (Handle SingleRel)
> * RelMdDistribution (Handle SingleRel)
> * RelMdDistinctRowCount（Handle RelNode）
> * RelMdExplainVisibility（Only TableScan）
> * RelMdLowerBoundCost（Handle RelNode）
> * RelMdMemory（Handle RelNode）
> * RelMdParallelism（Handle RelNode）
> * RelMdPercentageOriginalRows（Handle RelNode）
> * RelMdPopulationSize（Handle RelNode）
> * RelMdSelectivity（Must have predicate）
> * RelMdSize（Handle RelNode）
> * RelMdUniqueKeys（Handle SingleRel）
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