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Haisheng Yuan commented on CALCITE-3015: ---------------------------------------- Nah, if the table is empty, you are screwed up. > 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}}. -- This message was sent by Atlassian JIRA (v7.6.3#76005)