[SPARK-27978] Add built-in Aggregate Functions: string_agg

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 3.0.0
• Component/s: SQL
• Assignee: Unassigned
• Reporter: Yuming Wang
• Created: 08/Jun/19 01:32
• Updated: 29/Dec/19 11:45
• Resolved: 29/Dec/19 11:45

Description

Function	Argument Type(s)	Return Type	Partial Mode	Description
string_agg(expression,delimiter)	(text, text) or (bytea, bytea)	same as argument types	No	input values concatenated into a string, separated by delimiter

https://www.postgresql.org/docs/current/functions-aggregate.html

We can workaround it by concat_ws(delimiter, collect_list(expression)) currently.