[
https://issues.apache.org/jira/browse/CALCITE-2045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16254217#comment-16254217
]
Julian Hyde commented on CALCITE-2045:
--------------------------------------
Here's what's in the SQL standard (verbatim, but I've removed some lines):
{noformat}
<user-defined type definition> ::=
CREATE TYPE <user-defined type body>
<user-defined type body> ::=
<schema-resolved user-defined type name>
[ <subtype clause> ]
[ AS <representation> ]
[ <user-defined type option list> ]
[ <method specification list> ]
<user-defined type option list> ::=
<user-defined type option> [ <user-defined type option>... ]
<user-defined type option> ::=
<instantiable clause>
| <finality>
| <reference type specification>
| <cast to ref>
| <cast to type>
| <cast to distinct>
| <cast to source>
<subtype clause> ::=
UNDER <supertype name>
<supertype name> ::=
<path-resolved user-defined type name>
<representation> ::=
<predefined type>
| <collection type>
| <member list>
<member list> ::=
<left paren> <member> [ { <comma> <member> }... ] <right paren>
<member> ::=
<attribute definition>
<instantiable clause> ::=
INSTANTIABLE
| NOT INSTANTIABLE
<finality> ::=
FINAL
| NOT FINAL
<attribute definition> ::=
<attribute name> <data type>
[ <attribute default> ]
[ <collate clause> ]
<attribute default> ::=
<default clause>
{noformat}
Of the features in the standard, I don't think we should allow {{<user-defined
type option>}} or {{<subtype clause>}} or {{<collection type>}} at this point.
We might add them later.
I don't think we should allow distinct types to be flagged {{NULL}} or {{NOT
NULL}}.
I think we should add {{OR REPLACE}}, consistent with other Calcite {{CREATE}}
commands.
Which gives us this:
{noformat}
CREATE [ OR REPLACE ] TYPE [ schema_name. ] type_name
{
AS base_type
| AS ( attributeDef [, attributeDef ]* )
}
attributeDef:
attribute_name data_type
[ COLLATE collation ]
[ NULL | NOT NULL ]
[ DEFAULT expression ]
{noformat}
Examples:
{code}
CREATE TYPE metric_meter AS DOUBLE;
CREATE OR REPLACE TYPE imperial_foot AS DOUBLE;
CREATE TYPE mySchema.Circle AS (
radius DOUBLE DEFAULT 1
);
{code}
There is a [very nice write-up of SQL UDTs in
Farrago|http://farrago.sourceforge.net/design/UserDefinedTypesAndRoutines.html],
an ancestor project of Calcite. We could mine that for further examples.
> Support "CREATE TYPE" DDL
> -------------------------
>
> Key: CALCITE-2045
> URL: https://issues.apache.org/jira/browse/CALCITE-2045
> Project: Calcite
> Issue Type: New Feature
> Components: core
> Reporter: Shuyi Chen
> Assignee: Julian Hyde
>
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
