[jira] [Commented] (CALCITE-6275) Parser for data types ignores element nullability in collections

["Dmitry Sysolyatin (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-6275?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17887866#comment-17887866 ] 

Dmitry Sysolyatin commented on CALCITE-6275:
--------------------------------------------

Hi [~mbudiu] 
I created a similar bug related to the nullability of elements inside SqlCollectionTypeNameSpec [1], but without the parsing part, as I was more interested in the unparsing part. The issue arose because the ClickHouse SQL dialect supports specifying the nullability of a collection. Here's an example:
{code:java}
CREATE TABLE t_arr
(
    `arr` Array(Nullable(UInt8))
)
ENGINE = MergeTree
ORDER BY tuple()
{code}

So, I believe that this bug is valid.

[1] https://issues.apache.org/jira/browse/CALCITE-6101

> 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
>             Fix For: 1.38.0
>
>
> 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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