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https://issues.apache.org/jira/browse/CALCITE-6275?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17820246#comment-17820246
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Mihai Budiu commented on CALCITE-6275:
--------------------------------------
The Calcite IR can actually represent all these types unambiguously.
Are you implying that array and map elements can always be null? That's a
possible interpretation. Ideally the interpretation should be dialect-specific.
The array constructor may infer array types that have non-nullable elements;
e.g.: ARRAY[1,2] has type INTEGER NOT NULL ARRAY. If all arrays have nullable
elements, the inferred type should instead be INTEGER ARRAY.
Every language that has an Option type
[https://en.wikipedia.org/wiki/Option_type] has done this right, including
Standard ML, maybe more than 30 years ago.
It does look messy. I will think about this a bit more and decide whether this
issue should be closed as invalid or not.
> Parser for data types ignores element nullability in collections
> ----------------------------------------------------------------
>
> Key: CALCITE-6275
> URL: https://issues.apache.org/jira/browse/CALCITE-6275
> Project: Calcite
> Issue Type: Bug
> Components: core, server
> Affects Versions: 1.36.0
> Reporter: Mihai Budiu
> Priority: Major
> Labels: pull-request-available
>
> The parser (Parser.jj) has this production rule for DataType:
> {code}
> // Type name with optional scale and precision.
> SqlDataTypeSpec DataType() :
> {
> SqlTypeNameSpec typeName;
> final Span s;
> }
> {
> typeName = TypeName() {
> s = Span.of(typeName.getParserPos());
> }
> (
> typeName = CollectionsTypeName(typeName)
> )*
> {
> return new SqlDataTypeSpec(typeName,
> s.add(typeName.getParserPos()).pos());
> }
> }
> {code}
> Note that there is no way to specify the nullability for the elements of a
> collection, they are always assumed to be non-null. This is most pertinent
> for the server component, where in DDL one cannot specify a table column of
> type INTEGER ARRAY; one always gets an INTEGER NOT NULL ARRAY instead.
> But note that SqlCollectionTypeNameSpec cannot even represent the nullability
> of the elements' type, it takes a SqlTypeNameSpec instead of a
> SqlDataTypeSpec.
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