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https://issues.apache.org/jira/browse/IGNITE-16396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17493342#comment-17493342
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Aleksey Plekhanov commented on IGNITE-16396:
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[~zstan], [~tledkov-gridgain], [~korlov], can you please review the patch?
> Calcite engine. Allow hash output distribution for aggregations
> ----------------------------------------------------------------
>
> Key: IGNITE-16396
> URL: https://issues.apache.org/jira/browse/IGNITE-16396
> Project: Ignite
> Issue Type: Improvement
> Reporter: Aleksey Plekhanov
> Assignee: Aleksey Plekhanov
> Priority: Major
> Labels: calcite2-required, calcite3-required
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Currently, we allow only single output distribution for aggregates, but looks
> like if we have hash input distribution and all grouping set contains all of
> the distribution keys we can make aggregation on remote nodes and produce
> hash output distribution with the same keys. This will reduce memory
> consumption on the initiator node and make some other optimizations possible.
> For example, query:
> {noformat}
> SELECT t1.aff_key, t2.cnt FROM t1 JOIN (SELECT aff_key, COUNT(*) AS cnt FROM
> t2 GROUP BY id) AS t2 ON t1.aff_key = t2.aff_key{noformat}
> Can do colocated join if both tables are colocated on {{{}aff_key{}}}.
> Currently, such a query does join on the initiator node.
> The same for set-ops (EXCEPT, INTERSECT).
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