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https://issues.apache.org/jira/browse/CALCITE-970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Julian Hyde resolved CALCITE-970.
---------------------------------
Resolution: Fixed
Fix Version/s: 1.6.0
Fixed in http://git-wip-us.apache.org/repos/asf/calcite/commit/19a67e1d.
> If NULLS FIRST/LAST not specified, sort NULL values HIGH
> --------------------------------------------------------
>
> Key: CALCITE-970
> URL: https://issues.apache.org/jira/browse/CALCITE-970
> Project: Calcite
> Issue Type: Bug
> Reporter: Julian Hyde
> Assignee: Julian Hyde
> Fix For: 1.6.0
>
>
> We have not specified what Calcite does if you do not specify NULLS FIRST or
> NULLS LAST. The policy seems to have been to always sort nulls first, but was
> not consistent (see CALCITE-969).
> Now Calcite will treat nulls as HIGH by default. That means NULLS LAST is
> assumed for ASC, NULLS FIRST is assumed for DESC. This is the same behavior
> as Oracle.
> If a project does not like this behavior, they can change the new parameter
> "defaultNullCollation", which allows alternative policies. Its value is
> defined by {code}enum NullCollation { LOW, HIGH, FIRST, LAST }{code}
> The "defaultNullCollation" parameter only applies to user SQL. If you create
> a RelFieldCollation via RelBuilder or directly, and do not specify a
> NullDirection value, you will get HIGH semantics. We used to use
> NullDirection.UNSPECIFIED quite widely in RelNode land, and now it is very
> rarely used, except with Direction.CLUSTERED.
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