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https://issues.apache.org/jira/browse/CALCITE-2658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16793427#comment-16793427
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Chunwei Lei edited comment on CALCITE-2658 at 3/15/19 8:03 AM:
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[~zabetak] Thanks. I really appreciate it much if someone can have a look.


was (Author: chunwei lei):
[~zabetak] Thanks. I really appreciate it very much if someone can have a look.

> Introducing more ReduceExpressionRules
> --------------------------------------
>
>                 Key: CALCITE-2658
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2658
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Chunwei Lei
>            Assignee: Julian Hyde
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 1h 40m
>  Remaining Estimate: 0h
>
> 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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