Recursive CTE throws temp tablespace is empty error

I need to aggregate the contents of multiple rows into a row as a delimited text. Here's the simplified table with sample data which represents what i want to do. CREATE TABLE SPD_OWNER.EMP ( EMPID NUMBER, NAME VARCHAR2(20), MGRID NUMBER, DEPT VARCHAR2(5) ); INSERT INTO EMP (EMPID, NAME, MGRID, DEPT) VALUES(1, 'GPM', NULL, 'IT'); INSERT INTO EMP (EMPID, NAME, MGRID, DEPT) VALUES(2, 'SPM', 1, 'IT'); INSERT INTO EMP (EMPID, NAME, MGRID, DEPT) VALUES(3, 'PM', 2, 'IT'); INSERT INTO EMP (EMPID, NAME, MGRID, DEPT) VALUES(4, 'Dev1', 3, 'IT'); INSERT INTO EMP (EMPID, NAME, MGRID, DEPT) VALUES(5, 'Dev2', 4, 'IT'); -- query which has issue WITH tmp (rnum,dept,id) AS (SELECT rownum rnum, dept, to_char(empid) AS id FROM (SELECT dept, empid FROM emp WHERE dept='IT' ORDER BY empid)), cte (rnum,dept,id) AS (SELECT rnum, dept, id FROM tmp WHERE rnum=1 UNION ALL SELECT cte.rnum+1, tmp.dept, cte.id||'/'||tmp.id FROM cte JOIN tmp on tmp.rnum=cte.rnum+1) SELECT * FROM cte cte1 WHERE rnum=(SELECT max(rnum) FROM cte cte2 WHERE cte1.dept=cte2.dept); Am expecting below output. 5 IT 1/2/3/4/5 But running above query gives me an error SQL Error : ORA-25153: Temporary Tablespace is Empty Isn't the condition tmp.rnum=cte.rnum+1 sufficient to break the recursive loop? Here's what am imagining to be happening. 1. 1st select (above union all) will select rnum=1 2. 1st recursive iteration will select tmp.rnum=cte.rnum+1, i.e. tmp.rnum=2 3. 2nd recursive iteration will select tmp.rnum=3 4. and so on till this condition is invalid, i.e. when cte.rnum=5 (because then tmp.rum=5+1 will not have matching record) Am assuming that am getting the error since it's going into infinite loop. What am i missing? Side Note: Am using Oracle DB, so i can easily do this using LISTAGG. But i also want to run this query in H2 DB. So i want to have a solution that uses standard sql. Am open to other ways to achieve the same result.