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https://issues.apache.org/jira/browse/CALCITE-482?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16902530#comment-16902530
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Haisheng Yuan commented on CALCITE-482:
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Is it necessary to support 2 different styles of hints? It looks powerful, 
mixed with Oracle and Sql Server style, yet it will increase the complexity and 
maintenance cost.

> Implement sql and planner hints
> -------------------------------
>
>                 Key: CALCITE-482
>                 URL: https://issues.apache.org/jira/browse/CALCITE-482
>             Project: Calcite
>          Issue Type: Bug
>    Affects Versions: 1.0.0-incubating
>            Reporter: Vladimir Sitnikov
>            Assignee: Danny Chan
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 2h
>  Remaining Estimate: 0h
>
> Query optimizer can never be perfect, so it makes sense to implement hints to 
> allow user better control the execution.
> For instance: "never merge this subquery with others" (`/+ no_merge/`), 
> "treat those tables as leading ones" (`/*+ leading */`), etc.
> Hints would enable predictable performance and the planning time would be 
> improved as well.



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