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https://issues.apache.org/jira/browse/IMPALA-12371?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zoltán Borók-Nagy reassigned IMPALA-12371:
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Assignee: Zoltán Borók-Nagy
> Add better cardinality estimation for Iceberg V2 tables with deletes
> --------------------------------------------------------------------
>
> Key: IMPALA-12371
> URL: https://issues.apache.org/jira/browse/IMPALA-12371
> Project: IMPALA
> Issue Type: Bug
> Components: Frontend
> Reporter: Zoltán Borók-Nagy
> Assignee: Zoltán Borók-Nagy
> Priority: Major
> Labels: impala-iceberg
>
> IMPALA-11797 is about the generic case, i.e. better cardinality for all ANTI
> JOIN operators.
> For Iceberg V2 we can safely come up with a better cardinality estimation as
> we can assume that all rows at RHS have a match in LHS when there is no
> filtering. Though RHS might contain duplicate rows, see:
> https://github.com/apache/iceberg/blob/462a203e67dd42d111a7fd2d3a0090b5aeb80833/api/src/main/java/org/apache/iceberg/RowDelta.java#L132-L133
> So we can come up something like this:
> Cardinality of DELETE operator = Cardinality(LHS) - (Cardinality(RHS) *
> selectivity of LHS)
> With some safety checks if it becomes negative (due to duplicates in RHS).
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