[SPARK-31225] Override `sql` method for OuterReference

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.1.0
• Fix Version/s: 2.4.8, 3.0.0
• Component/s: SQL
• Assignee: Kent Yao 2
• Reporter: Kent Yao 2
• Created: 23/Mar/20 07:15
• Updated: 21/Apr/21 07:23
• Resolved: 27/Mar/20 07:57

Description

OuterReference is LeafExpression, so it's children is Nil, which makes its SQL representation always be outer(). This makes our explain-command and error msg unclear when OuterReference exists

Issue Links

• links to: [Github] Pull Request #32256 (yaooqinn)
• links to: [Github] Pull Request #32256 (yaooqinn)
• links to: GitHub Pull Request #27985