Unexpected behavior in Oracle when using Group By with JSON_TABLE

Question

I have a denormalized VIEW we'll call VIEW_X which looks like the following (It's just a regular simple view - not materialized or anything like that):

ID   GROUP_ID   PART_1_ID                               PART_2_ID
1    1723189    cd69f0f4-a5ed-4196-916d-401e98ffec75    X1
1    1723189    cd69f0f4-a5ed-4196-916d-401e98ffec75    X2
2    1723185    8d5132cb-1b6e-4e79-9698-fd1962eb808f    K1
2    1723188    a191cb01-32ac-4ab4-bd6b-3ef777e395ca    K1

It's denormalized in that it actually represents a structure like this:

{
  id: 1,
  group_id: 1723189,
  part_1_id: 'cd69f0f4-a5ed-4196-916d-401e98ffec75'
  part_2_ids: ["X1", "X2"]
}

the PART_2_ID in this view is the result of selecting from a JSON_TABLE where the data in the original table is stored in an array like ["X1", "X2"] :

JSON_TABLE(a.PART_2_IDS, '$' COLUMNS (
            NESTED PATH '$[*]'
              COLUMNS (
                  PART_2_ID  VARCHAR2(4000) PATH '$'
                )
            )) p2

When I run a query like this on this view I get 0 results although the expected result is a single result with the ID of 2 :

SELECT ID
FROM VIEW_X
WHERE PART_2_ID IN ('K1')
GROUP BY ID
HAVING COUNT(DISTINCT(PART_2_ID)) = 1

ID
--
(no results)

figure 1

Curiously enough if I run just the following I get the expected two results as there are two rows with ID 2 where there is a match on PART_2_ID as K1 :

SELECT ID
FROM VIEW_X
WHERE PART_2_ID IN ('K1')

ID
--
 2
 2

If, however, I run either of the following queries I get a match on ID 1 :

SELECT ID
FROM VIEW_X
WHERE PART_2_ID IN ('X1')
GROUP BY ID
HAVING COUNT(DISTINCT(PART_2_ID)) = 1

ID
--
 1

SELECT ID
FROM VIEW_X
WHERE PART_2_ID IN ('X1', 'X2')
GROUP BY ID
HAVING COUNT(DISTINCT(PART_2_ID)) = 2

ID
--
 1

I don't understand why figure 1 is not returning the expected result - is there something I'm overlooking? Is this a quirk with how JSON_TABLE works?

Answer 1

I cannot replicate this in:

• Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production ; or
• Oracle Database 18c Enterprise Edition Release 18.0.0.0.0 - Production on https://livesql.oracle.com

Oracle Setup :

CREATE TABLE table1 ( document CLOB CONSTRAINT ensure_json CHECK (document IS JSON) );

INSERT INTO table1 ( document ) VALUES ( '{"id":1,"group_id":1723189,"part_1_id":"cd69f0f4-a5ed-4196-916d-401e98ffec75","part_2_ids":["X1","X2"]}' );
INSERT INTO table1 ( document ) VALUES ( '{"id":2,"group_id":1723185,"part_1_id":"8d5132cb-1b6e-4e79-9698-fd1962eb808f","part_2_ids":["K1"]}' );
INSERT INTO table1 ( document ) VALUES ( '{"id":2,"group_id":1723188,"part_1_id":"a191cb01-32ac-4ab4-bd6b-3ef777e395ca","part_2_ids":["K1"]}' );

CREATE VIEW VIEW_X AS
SELECT p.*
FROM   table1 t
       CROSS JOIN
       JSON_TABLE(
         t.document,
         '$'
         COLUMNS (
           id        PATH '$.id',
           group_id  PATH '$.group_id',
           part_1_id PATH '$.part_1_id',
           NESTED PATH '$.part_2_ids[*]'
             COLUMNS (
               PART_2_ID  VARCHAR2(4000) PATH '$'
             )
           )
         ) p;

Query 1 :

SELECT *
FROM   VIEW_X;

Results :

        ID   GROUP_ID PART_1_ID                            PART_2_ID
---------- ---------- ------------------------------------ ---------
         1    1723189 cd69f0f4-a5ed-4196-916d-401e98ffec75 X1   
         1    1723189 cd69f0f4-a5ed-4196-916d-401e98ffec75 X2   
         2    1723185 8d5132cb-1b6e-4e79-9698-fd1962eb808f K1   
         2    1723188 a191cb01-32ac-4ab4-bd6b-3ef777e395ca K1   

Query 2 :

SELECT ID
FROM VIEW_X
WHERE PART_2_ID IN ('K1')
GROUP BY ID
HAVING COUNT(DISTINCT(PART_2_ID)) = 1;

Results :

ID
--
 2