[CALCITE-5523] RelToSql converter generates GROUP BY clause with window expression

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: jdbc-adapter
• Labels: pull-request-available
• Assignee: Jiajun Xie
• Reporter: Leonid Chistov
• Created: 09/Feb/23 14:18
• Updated: 04/Oct/23 12:57

Description

Wrong SQL code is generated when aggregation is done on the field being a result of window expression evaluation.

Example can be demonstrated by adding following code to RelToSqlConverterTest.java:

@Test void testConvertWindowGroupByToSql() {
  String query = "SELECT * FROM ("
      + "SELECT rank() over (order by \"hire_date\") \"rank\" FROM \"employee\""
      + ") GROUP BY \"rank\"";
  String expected ="SELECT * FROM ("
      + "SELECT rank() over (order by \"hire_date\") AS \"$0\" FROM \"employee\""
      + ") GROUP BY \"$0\"";

  sql(query).ok(expected);
}

Generated SQL code will look like:

SELECT RANK() OVER (ORDER BY hire_date) AS rank
FROM foodmart.employee
GROUP BY RANK() OVER (ORDER BY hire_date)

This is incorrect - window expressions are not allowed in GROUP BY clause by SQL standard and Calcite itself would produce following error message if this SQL code would be passed as input: 

Windowed aggregate expression is illegal in GROUP BY clause 

Issue Links

• relates to: CALCITE-5502 RelToSql converter generates where clause with window expression
• links to: GitHub Pull Request #3431