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https://issues.apache.org/jira/browse/CALCITE-672?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14483862#comment-14483862
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Jinfeng Ni commented on CALCITE-672:
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ANY NOT NULL is possible, only when we know the possible types presented by
"ANY" all are NOT NULLable. If we do not have such knowledge, it does not make
sense to create a ANY NOT NULL type, to represent possibly NULLABLE types.
For instance, why does SqlItemOperator would return ANY NULL, while
SqlUnresolvedFunction would return ANY NOT NULL?
> SQL "any" type should be created as nullable in RelDataTypeFactory.
> --------------------------------------------------------------------
>
> Key: CALCITE-672
> URL: https://issues.apache.org/jira/browse/CALCITE-672
> Project: Calcite
> Issue Type: Bug
> Reporter: Jinfeng Ni
> Assignee: Julian Hyde
>
> Calcite uses SQL "any" type internally, when the type of an Rex expression is
> not known precisely. By its name, "any" could mean nullable type, or
> non-nullable type. Therefore, it makes sense to create SQL "any" type as
> nullable type.
> However, in the Calcite code, the nullability of "any" type is not set
> consistently. For example, the SqlItemOperator would set "any" as nullable,
> while SqlUnresolvedFunction will set "any" as non-nullable.
> SQL "any" type is used extensively in Schema-less system like Drill, since
> the exact SQL type would be determined in run-time only. Having an
> inconsistent nullability through Calcite library will cause issues for a
> schema-less system.
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