Ruben Q L created CALCITE-4208:
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Summary: Improve metadata row count for Join
Key: CALCITE-4208
URL: https://issues.apache.org/jira/browse/CALCITE-4208
Project: Calcite
Issue Type: Improvement
Components: core
Reporter: Ruben Q L
Currently, the default metadata row count for join
{{RelMdRowCount#getRowCount(Join rel, RelMetadataQuery mq)}} relies on
{{RelMdUtil.getJoinRowCount}}. This method has several issues:
- In case of ANTI join, it returns the same estimation as a SEMI join
- In other cases (INNER, LEFT, RIGHT, FULL), it returns always the same
formula:
{{leftRowCount * rightRowCount * mq.getSelectivity(join, condition)}}
which seems valid for an INNER join, but not for LEFT / RIGHT / FULL.
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