[CALCITE-3964] Support <data type> in DESCRIPTOR operator

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Rui Wang
• Reporter: Rui Wang
• Created: 29/Apr/20 23:03
• Updated: 30/Apr/20 21:21

Description

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>

<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.

Issue Links

• is a child of: CALCITE-2270 [SQL:2016] Polymorphic table functions