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https://issues.apache.org/jira/browse/CALCITE-6817?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17925827#comment-17925827
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Mihai Budiu commented on CALCITE-6817:
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An example can be seen in my last PR:
https://github.com/apache/calcite/pull/4183
Here I wanted to check the types produced by a query, but the type digest
(which is used in the toString method) shows up as:
RecordType(INTEGER EXPR$0). However, from this one cannot tell whether EXPR$0
is nullable or not - the digest looks the same in both cases.
> Add string representation of default nulls direction for RelNode
> ----------------------------------------------------------------
>
> Key: CALCITE-6817
> URL: https://issues.apache.org/jira/browse/CALCITE-6817
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.38.0
> Reporter: ZheHu
> Assignee: ZheHu
> Priority: Minor
> Labels: pull-request-available
> Fix For: 1.39.0
>
>
> Calcite has the same hehavior with Oracle on returning the null direction if
> not specified, which means NULLS LAST is assumed for ASC and NULLS FIRST is
> assumed for DESC.
> However, the default nulls direction is not presented in plan traces. For
> example:
> {code:java}
> select empno from emp order by empno desc
> {code}
> has the following plan:
> {code:java}
> LogicalSort(sort0=[$0], dir0=[DESC])
> LogicalProject(EMPNO=[$0])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> It makes RelNode clearer if adding nulls direction, so the above plan will be
> like:
> {code:java}
> LogicalSort(sort0=[$0], dir0=[DESC-nulls-first])
> LogicalProject(EMPNO=[$0])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
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