[OAK-10261] Query with OR clause with COALESCE function incorrectly interpreted

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.54.0
• Component/s: query
• Assignee: Thomas Mueller
• Reporter: Thomas Mueller
• Created: 24/May/23 12:57
• Updated: 24/Jul/23 17:33
• Resolved: 25/May/23 05:50

Description

The "coalesce" function incorrectly asks the index to do "is not null" for the first property:

SELECT a.* 
FROM [dam:Asset] AS a 
WHERE ((COALESCE(a.[jcr:lastModified], a.[jcr:created]) < cast('2023-05-08T20:51:06.239+03:00' AS date)) 
OR (COALESCE(a.[jcr:lastModified], a.[jcr:created]) = cast('2023-05-08T20:51:06.239+03:00' AS date) 

[dam:Asset] as [asset] /* lucene:fragments-9(/oak:index/fragments-9)  
+jcr:lastModified:[-9223372036854775808 TO 9223372036854775807]  
 */ 

This is because the Coalesce implementation uses an incorrect "getPropertyExistence" method. It is implemented as follows, so that it implies the first operand is not null, which is incorrect: the first operand can be null. Even the second operand can be null; just the combination can't be null - but there seems to be no good reason to inform the index to do this.

    // this is wrong:
    @Override
    public PropertyExistenceImpl getPropertyExistence() {
        PropertyExistenceImpl pe = operand1.getPropertyExistence();
        return pe != null ? pe : operand2.getPropertyExistence();
    }