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https://issues.apache.org/jira/browse/CALCITE-5994?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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LakeShen updated CALCITE-5994:
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Summary: Add optimization rule to remove Sort when its input's row number
is less or equal to one (was: Add the optimize for removing the redundant
order by when its source row number is less than or equal 1)
> Add optimization rule to remove Sort when its input's row number is less or
> equal to one
> ----------------------------------------------------------------------------------------
>
> Key: CALCITE-5994
> URL: https://issues.apache.org/jira/browse/CALCITE-5994
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: LakeShen
> Assignee: LakeShen
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.36.0
>
>
> When a Sort's input source max row numer is 1,then we could remove the
> redundant Sort,the Sort could be a sorted semantic Sort(offset and fetch is
> null).
> For example,the sql:
> {code:java}
> select * from (select * from tableA limit 1) order by c ;
> {code}
> because the `(select * from tableA limit 1) ` max row number is 1, then we
> could remove order by c
> {code:java}
> select * from tableA limit 1;
> {code}
> The sql:
> {code:java}
> select max(totalprice) from orders order by 1 {code}
> could converted to:
> {code:java}
> select max(totalprice) from orders{code}
> Above logic are same as Presto/Trino's
> [RemoveRedundantSort|https://github.com/prestodb/presto/blob/c21fc28846252cd910d90f046514bf586d7bb5c6/presto-main/src/main/java/com/facebook/presto/sql/planner/iterative/rule/RemoveRedundantSort.java#L27]
> rule:
>
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