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https://issues.apache.org/jira/browse/CALCITE-2658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16679203#comment-16679203
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Chunwei Lei edited comment on CALCITE-2658 at 11/13/18 6:09 AM:
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Thanks [~julianhyde]

I will create another [jira|https://issues.apache.org/jira/browse/CALCITE-2661] 
to support creating Exchange and SortExchange in RelBuilder.


was (Author: chunwei lei):
Thanks [~julianhyde]

I will create another jira to support creating Exchange and SortExchange in 
RelBuilder.

> Introducing more ReduceExpressionRules
> --------------------------------------
>
>                 Key: CALCITE-2658
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2658
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.17.0
>            Reporter: Chunwei Lei
>            Assignee: Julian Hyde
>            Priority: Major
>             Fix For: 1.18.0
>
>
> It is useful to have rules reducing Exchange/Sort/SortExchange keys, e.g.,
> SELECT key,value FROM (SELECT 1 AS key, value FROM src) r DISTRIBUTE BY key;
> can be reduced to 
> SELECT 1 AS key, value FROM src;    # Since singleton requirement may already 
> required by SELECT.
> SELECT key,value FROM (SELECT 1 AS key, value FROM src) r ORDER BY key;
> can be reduced to
> SELECT 1 AS key, value FROM src;    # Since ordering on constant is useless.



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