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https://issues.apache.org/jira/browse/SPARK-23757?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dongjoon Hyun updated SPARK-23757:
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Affects Version/s: (was: 3.0.0)
3.1.0
> [Performance] Star schema detection improvements
> ------------------------------------------------
>
> Key: SPARK-23757
> URL: https://issues.apache.org/jira/browse/SPARK-23757
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 3.1.0
> Reporter: Ioana Delaney
> Priority: Major
>
> Star schema consists of one or more fact tables referencing a number of
> dimension tables. Queries against star schema are expected to run fast
> because of the established RI constraints among the tables. In general, star
> schema joins are detected using the following conditions:
> 1. RI constraints (reliable detection)
> * Dimension contains a primary key that is being joined to the fact table.
> * Fact table contains foreign keys referencing multiple dimension tables.
> 2. Cardinality based heuristics
> * Usually, the table with the highest cardinality is the fact table.
> Existing SPARK-17791 uses a combination of the above two conditions to detect
> and optimize star joins. With support for informational RI constraints, the
> algorithm in SPARK-17791 can be improved with reliable RI detection.
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