[FLINK-14323] Serialize Expression to String and parse String to Expression

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Component/s: Table SQL / API, Table SQL / Planner
• Assignee: Unassigned
• Reporter: Jark Wu
• Created: 05/Oct/19 03:25
• Updated: 02/Apr/21 06:26
• Resolved: 02/Apr/21 06:26

Description

In order to persist/store the watermark strategy expression (and the future computed column expression), we should find a way to serialize Expression to String and parse String back to Expression.

More details can be discussed under this JIRA issue, and this may need another FLIP.

There are two ways:
1) introduce a SqlExpression which wraps the raw SQL string and resolved DataType. Only implement the asSerializableString for SqlExpression.
2) support all of the ResolvedExpressions’ asSerializableString.

Issue Links

• relates to: FLINK-14367 Fully support for converting RexNode to Expression