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Posted to issues@calcite.apache.org by "Chunwei Lei (JIRA)" <ji...@apache.org> on 2019/04/22 14:55:00 UTC
[jira] [Closed] (CALCITE-3015) Add rule to remove constants in
group keys
[ https://issues.apache.org/jira/browse/CALCITE-3015?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Chunwei Lei closed CALCITE-3015.
--------------------------------
Resolution: Invalid
> Add rule to remove constants in group keys
> ------------------------------------------
>
> Key: CALCITE-3015
> URL: https://issues.apache.org/jira/browse/CALCITE-3015
> Project: Calcite
> Issue Type: Improvement
> Reporter: Chunwei Lei
> Assignee: Chunwei Lei
> Priority: Major
>
> Constants in group keys can be removed to reduce shuffle. For instance,
>
> {code:java}
> select key, count(*) from (select 1 as key from src) dual group by key;
> {code}
> can be reduced to
> {code:java}
> select count(*) from (select 1 as key from src) dual;{code}
> It could save much resource in distribute system if all group keys are constants since the distribution becomes {{SINGLETON}} instead of {{HASH}}.
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