[FLINK-25341] Improve casting STRUCTURED type to STRING

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.15.0
• Component/s: Table SQL / Planner
• Labels: pull-request-available
• Assignee: Francesco Guardiani
• Reporter: Timo Walther
• Created: 16/Dec/21 08:53
• Updated: 13/Jan/22 17:25
• Resolved: 13/Jan/22 17:25

Description

Structured types currently use ROW to STRING logic. However, this is not very useful for users as the field order might be determined by Flink. Also, structured types has the nice property of defining a custom toString and attribute names.

I would suggest the following:

If the structured type has a StructuredType.getImplementationClass convert to external class and call toString.

If no implementation class is present or the toString is not possible, use the string representation of maps.

Issue Links

• links to: GitHub Pull Request #18182