Zhong Yu created CALCITE-2202:
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Summary: Aggregate Join Push-down on a Single Side
Key: CALCITE-2202
URL: https://issues.apache.org/jira/browse/CALCITE-2202
Project: Calcite
Issue Type: Improvement
Components: core
Affects Versions: next
Reporter: Zhong Yu
Assignee: Julian Hyde
Fix For: next
While investigating https://issues.apache.org/jira/browse/CALCITE-2195, it's
apparent that aggregation can be pushed on on a single side (either side), and
leave the other side non-aggregated, regardless of whether grouping columns are
unique on the other side. My analysis –
[http://zhong-j-yu.github.io/aggregate-join-push-down.pdf] .
This may be useful when the metadata is insufficient; in any case, we may try
to provide all 3 possible transformations (aggregate on left only; right only;
both sides) to the cost based optimizer, so that the cheapest one can be chosen
based on stats.
Does this make any sense, anybody? If it sounds good, I'll implement it and
offer a PR.
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