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https://issues.apache.org/jira/browse/CALCITE-969?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15006171#comment-15006171
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liyang commented on CALCITE-969:
--------------------------------
Copy solution discussion from email.
Julian Hyde <[email protected]>
Nov 14
For extra credit, the fix would allow the position of nulls to be configurable.
In CalciteConnectionProperty, add
enum NullCollation { LOW, HIGH, FIRST, LAST }
and
DEFAULT_NULL_COLLATION, default HIGH (last for ASC, first for DESC).
The minimum fix is to support HIGH without looking at a config property.
> Order by (A, B) and order by (A) treats NULL differently
> --------------------------------------------------------
>
> Key: CALCITE-969
> URL: https://issues.apache.org/jira/browse/CALCITE-969
> Project: Calcite
> Issue Type: Bug
> Reporter: liyang
> Assignee: Julian Hyde
>
> NULL first or NULL last is not clearly defined by sql spec, but should be
> consistent in calcite.
> I spot order by (A desc) returns NULL last, but order by (A desc, B) returns
> NULL first.
> E.g. "select cal_dt, country, ... from xxx order by COUNTRY DESC" returns
> 2013-08-11 US ....
> 2013-08-18 FR ....
> 2013-03-31 null ....
> 2013-11-10 null ....
> E.g. "select cal_dt, country, ... from xxx order by COUNTRY DESC, CAL_DT
> ASC" returns
> 2013-03-31 null ....
> 2013-11-10 null ....
> 2013-08-11 US ....
> 2013-08-18 FR ....
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