[jira] [Created] (CALCITE-3964) Support in DESCRIPTOR operator

["Rui Wang (Jira)" <ji...@apache.org>]

Rui Wang created CALCITE-3964:
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             Summary: 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


From SQL standard 2016

{code:sql}
8.15 <descriptor argument>
<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> ]
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.
{code}


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.



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