[
https://issues.apache.org/jira/browse/CALCITE-3964?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17096987#comment-17096987
]
Julian Hyde commented on CALCITE-3964:
--------------------------------------
The above description is a bit abstract; the SQL standard folks hate including
examples (because they are "non-normative") but a SQL example would help me
understand.
> Support <data type> in DESCRIPTOR operator
> -------------------------------------------
>
> Key: CALCITE-3964
> URL: https://issues.apache.org/jira/browse/CALCITE-3964
> Project: Calcite
> Issue Type: Sub-task
> Reporter: Rui Wang
> Assignee: Rui Wang
> Priority: Major
>
> DESCRIPTOR can include an optional data type, which will enable type checking
> in SQL validator. It is useful for streaming windowing: the windowing is
> required to be applied on TIMESTAMP type, and we can rely on descriptor to do
> type validation.
> *The following is copied from SQL standard 2016*:
> 8.15 <descriptor argument>
> {code:java}
> <descriptor argument> ::=
> <descriptor value constructor>
> <descriptor value constructor> ::=
> DESCRIPTOR <left paren> <descriptor column list> <right paren>
> <descriptor column list> ::=
> <descriptor column specification>
> [ { <comma> <descriptor column specification> }... ]
> <descriptor column specification> ::=
> <column name> [ <data type> ]
> {code}
> A <descriptor argument> is the keyword DESCRIPTOR followed by a parenthesized
> list of column names; each column name may optionally have a data type. If
> every column name has a data type, then the descriptor describes a row type.
> In the examples, CSVreader and Pivot use descriptor arguments that are just
> lists of column names; ExecR is an example that uses a descriptor to pass a
> complete row type.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
