Pavel Golub: MERGE in PostgreSQL

Found cool trick how today implement Orable MERGE in PostgreSQL:

Oracle statement:

1.  
2. MERGE INTO acme_obj_value d
3. USING(SELECT object_id
4.         FROM  acme_state_tmp
5.       ) s
6. ON(d.object_id = s.object_id)
7.   WHEN matched THEN
8.     UPDATESET d.date_value =LEAST(l_dt, d.date_value)
9.   WHENNOT matched THEN
10.     INSERT(d.id, d.object_id, d.date_value)
11.     VALUES(acme_param_sequence.NEXTVAL, s.object_id, l_dt)
12.  

PostgreSQL statement:

1.  
2. WITH s AS(
3.      SELECT object_id
4.      FROM  acme_state_tmp
5. ),
6. upd AS(
7.      UPDATE acme_obj_value
8.      SET   date_value =LEAST(l_dt, d.date_value)
9.      FROM  s
10.      WHERE acme_obj_value.object_id = s.object_id
11.      RETURNING acme_obj_value.object_id
12. )
13. INSERTINTO acme_obj_value(id, object_id, date_value)
14. SELECTNEXTVAL('acme_param_sequence'), s.object_id, l_dt
15. FROM  s
16. WHERE s.object_id NOTIN(SELECT object_id FROM upd)
17.