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https://issues.apache.org/jira/browse/CALCITE-482?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17014905#comment-17014905
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Vladimir Sitnikov commented on CALCITE-482:
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{quote} Why do you think we should take the map into account... in
SortProjectTransposeRule, and for that case, we should not copy the hints{quote}
{noformat}
SortProjectTransposeRule
equiv = ImmutableMap.of((RelNode) newSort, project.getInput());
call.transformTo(newProject, equiv);
{noformat}
As far as I can read it, the hints should be propagated from
`project.getInput()` to `newSort`
> Implement SQL and planner hints
> -------------------------------
>
> Key: CALCITE-482
> URL: https://issues.apache.org/jira/browse/CALCITE-482
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.21.0
> Reporter: Vladimir Sitnikov
> Assignee: Danny Chen
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.22.0
>
> Time Spent: 8h 10m
> 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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