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https://issues.apache.org/jira/browse/SPARK-28860?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dongjoon Hyun updated SPARK-28860:
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Affects Version/s: (was: 3.0.0)
3.1.0
> Using ColumnStats of join key to get TableAccessCardinality when finding
> star joins in ReorderJoinRule
> -------------------------------------------------------------------------------------------------------
>
> Key: SPARK-28860
> URL: https://issues.apache.org/jira/browse/SPARK-28860
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.1.0
> Reporter: Lai Zhou
> Priority: Minor
>
> Now the star-schema detection uses TableAccessCardinality to reorder
> DimTables when there is a selectiveStarJoin .
> [StarSchemaDetection.scala#L341|https://github.com/apache/spark/blob/98e1a4cea44d7cb2f6d502c0202ad3cac2a1ad8d/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/StarSchemaDetection.scala#L341]
> {code:java}
> if (isSelectiveStarJoin(dimTables, conditions)) {
> val reorderDimTables = dimTables.map {
> plan => TableAccessCardinality(plan, getTableAccessCardinality(plan)) }
> .sortBy(_.size).map {
> case TableAccessCardinality(p1, _) => p1
> }{code}
>
> But the getTableAccessCardinality method does't consider the ColumnStats of
> the equi-join-key. I'm not sure if we should compute Join cardinality for the
> dimTable based on it's join key here.
> [~ioana-delaney]
>
>
>
>
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