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https://issues.apache.org/jira/browse/IMPALA-8033?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Paul Rogers reassigned IMPALA-8033:
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Assignee: (was: Paul Rogers)
> PlanNode getInputCardinality has two conflicting meanings
> ---------------------------------------------------------
>
> Key: IMPALA-8033
> URL: https://issues.apache.org/jira/browse/IMPALA-8033
> Project: IMPALA
> Issue Type: Bug
> Components: Frontend
> Affects Versions: Impala 3.1.0
> Reporter: Paul Rogers
> Priority: Minor
>
> The use of the method {{PlanNode.getInputCardinality()}} has evolved to have
> two slightly different, but conflicting, meanings:
> * The actual cardinality of the input table, needed to compute join
> cardinality.
> * The number of rows to be read, taking into consideration any limits placed
> on reading.
> Because join calculations are wrong if we do not use the actual base table
> cardinality, we cannot use the input cardinality interchangeably with table
> cardinality.
> Instead, break the function into two: {{getTableCardinality()}} to get the
> actual cardinality for use in joins, and the existing
> {{getInputCardinality()}} used for other purposes.
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