--
-- MERGE
--
CREATE USER regress_merge_privs;
CREATE USER regress_merge_no_privs;
CREATE USER regress_merge_none;
DROP TABLE IF EXISTS target;
NOTICE:  table "target" does not exist, skipping
DROP TABLE IF EXISTS source;
NOTICE:  table "source" does not exist, skipping
CREATE TABLE target (tid integer, balance integer)
  WITH (autovacuum_enabled=off);
CREATE TABLE source (sid integer, delta integer) -- no index
  WITH (autovacuum_enabled=off);
INSERT INTO target VALUES (1, 10);
INSERT INTO target VALUES (2, 20);
INSERT INTO target VALUES (3, 30);
SELECT t.ctid is not null as matched, t.*, s.* FROM source s FULL OUTER JOIN target t ON s.sid = t.tid ORDER BY t.tid, s.sid;
 matched | tid | balance | sid | delta 
---------+-----+---------+-----+-------
 t       |   1 |      10 |     |      
 t       |   2 |      20 |     |      
 t       |   3 |      30 |     |      
(3 rows)

ALTER TABLE target OWNER TO regress_merge_privs;
ALTER TABLE source OWNER TO regress_merge_privs;
CREATE TABLE target2 (tid integer, balance integer)
  WITH (autovacuum_enabled=off);
CREATE TABLE source2 (sid integer, delta integer)
  WITH (autovacuum_enabled=off);
ALTER TABLE target2 OWNER TO regress_merge_no_privs;
ALTER TABLE source2 OWNER TO regress_merge_no_privs;
GRANT INSERT ON target TO regress_merge_no_privs;
SET SESSION AUTHORIZATION regress_merge_privs;
EXPLAIN (COSTS OFF)
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	DELETE;
               QUERY PLAN               
----------------------------------------
 Merge on target t
   ->  Merge Join
         Merge Cond: (t.tid = s.sid)
         ->  Sort
               Sort Key: t.tid
               ->  Seq Scan on target t
         ->  Sort
               Sort Key: s.sid
               ->  Seq Scan on source s
(9 rows)

--
-- Errors
--
MERGE INTO target t RANDOMWORD
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0;
ERROR:  syntax error at or near "RANDOMWORD"
LINE 1: MERGE INTO target t RANDOMWORD
                            ^
-- MATCHED/INSERT error
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	INSERT DEFAULT VALUES;
ERROR:  syntax error at or near "INSERT"
LINE 5:  INSERT DEFAULT VALUES;
         ^
-- NOT MATCHED BY SOURCE/INSERT error
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED BY SOURCE THEN
	INSERT DEFAULT VALUES;
ERROR:  syntax error at or near "INSERT"
LINE 5:  INSERT DEFAULT VALUES;
         ^
-- incorrectly specifying INTO target
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT INTO target DEFAULT VALUES;
ERROR:  syntax error at or near "INTO"
LINE 5:  INSERT INTO target DEFAULT VALUES;
                ^
-- Multiple VALUES clause
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT VALUES (1,1), (2,2);
ERROR:  syntax error at or near ","
LINE 5:  INSERT VALUES (1,1), (2,2);
                            ^
-- SELECT query for INSERT
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT SELECT (1, 1);
ERROR:  syntax error at or near "SELECT"
LINE 5:  INSERT SELECT (1, 1);
                ^
-- NOT MATCHED/UPDATE
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	UPDATE SET balance = 0;
ERROR:  syntax error at or near "UPDATE"
LINE 5:  UPDATE SET balance = 0;
         ^
-- NOT MATCHED BY TARGET/UPDATE
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED BY TARGET THEN
	UPDATE SET balance = 0;
ERROR:  syntax error at or near "UPDATE"
LINE 5:  UPDATE SET balance = 0;
         ^
-- UPDATE tablename
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE target SET balance = 0;
ERROR:  syntax error at or near "target"
LINE 5:  UPDATE target SET balance = 0;
                ^
-- source and target names the same
MERGE INTO target
USING target
ON tid = tid
WHEN MATCHED THEN DO NOTHING;
ERROR:  name "target" specified more than once
DETAIL:  The name is used both as MERGE target table and data source.
-- used in a CTE without RETURNING
WITH foo AS (
  MERGE INTO target USING source ON (true)
  WHEN MATCHED THEN DELETE
) SELECT * FROM foo;
ERROR:  WITH query "foo" does not have a RETURNING clause
LINE 4: ) SELECT * FROM foo;
                        ^
-- used in COPY without RETURNING
COPY (
  MERGE INTO target USING source ON (true)
  WHEN MATCHED THEN DELETE
) TO stdout;
ERROR:  COPY query must have a RETURNING clause
-- unsupported relation types
-- materialized view
CREATE MATERIALIZED VIEW mv AS SELECT * FROM target;
MERGE INTO mv t
USING source s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT DEFAULT VALUES;
ERROR:  cannot execute MERGE on relation "mv"
DETAIL:  This operation is not supported for materialized views.
DROP MATERIALIZED VIEW mv;
-- permissions
SET SESSION AUTHORIZATION regress_merge_none;
MERGE INTO target
USING (SELECT 1)
ON true
WHEN MATCHED THEN
	DO NOTHING;
ERROR:  permission denied for table target
SET SESSION AUTHORIZATION regress_merge_privs;
MERGE INTO target
USING source2
ON target.tid = source2.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0;
ERROR:  permission denied for table source2
GRANT INSERT ON target TO regress_merge_no_privs;
SET SESSION AUTHORIZATION regress_merge_no_privs;
MERGE INTO target
USING source2
ON target.tid = source2.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0;
ERROR:  permission denied for table target
GRANT UPDATE ON target2 TO regress_merge_privs;
SET SESSION AUTHORIZATION regress_merge_privs;
MERGE INTO target2
USING source
ON target2.tid = source.sid
WHEN MATCHED THEN
	DELETE;
ERROR:  permission denied for table target2
MERGE INTO target2
USING source
ON target2.tid = source.sid
WHEN NOT MATCHED THEN
	INSERT DEFAULT VALUES;
ERROR:  permission denied for table target2
-- check if the target can be accessed from source relation subquery; we should
-- not be able to do so
MERGE INTO target t
USING (SELECT * FROM source WHERE t.tid > sid) s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT DEFAULT VALUES;
ERROR:  invalid reference to FROM-clause entry for table "t"
LINE 2: USING (SELECT * FROM source WHERE t.tid > sid) s
                                          ^
DETAIL:  There is an entry for table "t", but it cannot be referenced from this part of the query.
--
-- initial tests
--
-- zero rows in source has no effect
MERGE INTO target
USING source
ON target.tid = source.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	DELETE;
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT DEFAULT VALUES;
ROLLBACK;
-- insert some non-matching source rows to work from
INSERT INTO source VALUES (4, 40);
SELECT * FROM source ORDER BY sid;
 sid | delta 
-----+-------
   4 |    40
(1 row)

SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
(3 rows)

MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	DO NOTHING;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	DELETE;
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT DEFAULT VALUES;
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
     |        
(4 rows)

ROLLBACK;
-- DELETE/INSERT not matched by source/target
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED BY SOURCE THEN
	DELETE
WHEN NOT MATCHED BY TARGET THEN
	INSERT VALUES (s.sid, s.delta)
RETURNING merge_action(), t.*;
 merge_action | tid | balance 
--------------+-----+---------
 DELETE       |   1 |      10
 DELETE       |   2 |      20
 DELETE       |   3 |      30
 INSERT       |   4 |      40
(4 rows)

SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   4 |      40
(1 row)

ROLLBACK;
-- index plans
INSERT INTO target SELECT generate_series(1000,2500), 0;
ALTER TABLE target ADD PRIMARY KEY (tid);
ANALYZE target;
EXPLAIN (COSTS OFF)
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0;
               QUERY PLAN               
----------------------------------------
 Merge on target t
   ->  Hash Join
         Hash Cond: (s.sid = t.tid)
         ->  Seq Scan on source s
         ->  Hash
               ->  Seq Scan on target t
(6 rows)

EXPLAIN (COSTS OFF)
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	DELETE;
               QUERY PLAN               
----------------------------------------
 Merge on target t
   ->  Hash Join
         Hash Cond: (s.sid = t.tid)
         ->  Seq Scan on source s
         ->  Hash
               ->  Seq Scan on target t
(6 rows)

EXPLAIN (COSTS OFF)
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT VALUES (4, NULL);
               QUERY PLAN               
----------------------------------------
 Merge on target t
   ->  Hash Left Join
         Hash Cond: (s.sid = t.tid)
         ->  Seq Scan on source s
         ->  Hash
               ->  Seq Scan on target t
(6 rows)

DELETE FROM target WHERE tid > 100;
ANALYZE target;
-- insert some matching source rows to work from
INSERT INTO source VALUES (2, 5);
INSERT INTO source VALUES (3, 20);
SELECT * FROM source ORDER BY sid;
 sid | delta 
-----+-------
   2 |     5
   3 |    20
   4 |    40
(3 rows)

SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
(3 rows)

-- equivalent of an UPDATE join
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0;
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |       0
   3 |       0
(3 rows)

ROLLBACK;
-- equivalent of a DELETE join
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	DELETE;
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
(1 row)

ROLLBACK;
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	DO NOTHING;
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
(3 rows)

ROLLBACK;
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT VALUES (4, NULL);
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
   4 |        
(4 rows)

ROLLBACK;
-- duplicate source row causes multiple target row update ERROR
INSERT INTO source VALUES (2, 5);
SELECT * FROM source ORDER BY sid;
 sid | delta 
-----+-------
   2 |     5
   2 |     5
   3 |    20
   4 |    40
(4 rows)

SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
(3 rows)

BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0;
ERROR:  MERGE command cannot affect row a second time
HINT:  Ensure that not more than one source row matches any one target row.
ROLLBACK;
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	DELETE;
ERROR:  MERGE command cannot affect row a second time
HINT:  Ensure that not more than one source row matches any one target row.
ROLLBACK;
-- remove duplicate MATCHED data from source data
DELETE FROM source WHERE sid = 2;
INSERT INTO source VALUES (2, 5);
SELECT * FROM source ORDER BY sid;
 sid | delta 
-----+-------
   2 |     5
   3 |    20
   4 |    40
(3 rows)

SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
(3 rows)

-- duplicate source row on INSERT should fail because of target_pkey
INSERT INTO source VALUES (4, 40);
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
  INSERT VALUES (4, NULL);
ERROR:  duplicate key value violates unique constraint "target_pkey"
DETAIL:  Key (tid)=(4) already exists.
SELECT * FROM target ORDER BY tid;
ERROR:  current transaction is aborted, commands ignored until end of transaction block
ROLLBACK;
-- remove duplicate NOT MATCHED data from source data
DELETE FROM source WHERE sid = 4;
INSERT INTO source VALUES (4, 40);
SELECT * FROM source ORDER BY sid;
 sid | delta 
-----+-------
   2 |     5
   3 |    20
   4 |    40
(3 rows)

SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
(3 rows)

-- remove constraints
alter table target drop CONSTRAINT target_pkey;
alter table target alter column tid drop not null;
-- multiple actions
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT VALUES (4, 4)
WHEN MATCHED THEN
	UPDATE SET balance = 0;
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |       0
   3 |       0
   4 |       4
(4 rows)

ROLLBACK;
-- should be equivalent
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = 0
WHEN NOT MATCHED THEN
	INSERT VALUES (4, 4);
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |       0
   3 |       0
   4 |       4
(4 rows)

ROLLBACK;
-- column references
-- do a simple equivalent of an UPDATE join
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = t.balance + s.delta;
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      25
   3 |      50
(3 rows)

ROLLBACK;
-- do a simple equivalent of an INSERT SELECT
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT VALUES (s.sid, s.delta);
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
   4 |      40
(4 rows)

ROLLBACK;
-- and again with duplicate source rows
INSERT INTO source VALUES (5, 50);
INSERT INTO source VALUES (5, 50);
-- do a simple equivalent of an INSERT SELECT
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
  INSERT VALUES (s.sid, s.delta);
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
   4 |      40
   5 |      50
   5 |      50
(6 rows)

ROLLBACK;
-- removing duplicate source rows
DELETE FROM source WHERE sid = 5;
-- and again with explicitly identified column list
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT (tid, balance) VALUES (s.sid, s.delta);
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
   4 |      40
(4 rows)

ROLLBACK;
-- and again with a subtle error: referring to non-existent target row for NOT MATCHED
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT (tid, balance) VALUES (t.tid, s.delta);
ERROR:  invalid reference to FROM-clause entry for table "t"
LINE 5:  INSERT (tid, balance) VALUES (t.tid, s.delta);
                                       ^
DETAIL:  There is an entry for table "t", but it cannot be referenced from this part of the query.
-- and again with a constant ON clause
BEGIN;
MERGE INTO target t
USING source AS s
ON (SELECT true)
WHEN NOT MATCHED THEN
	INSERT (tid, balance) VALUES (t.tid, s.delta);
ERROR:  invalid reference to FROM-clause entry for table "t"
LINE 5:  INSERT (tid, balance) VALUES (t.tid, s.delta);
                                       ^
DETAIL:  There is an entry for table "t", but it cannot be referenced from this part of the query.
SELECT * FROM target ORDER BY tid;
ERROR:  current transaction is aborted, commands ignored until end of transaction block
ROLLBACK;
-- now the classic UPSERT
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = t.balance + s.delta
WHEN NOT MATCHED THEN
	INSERT VALUES (s.sid, s.delta);
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      25
   3 |      50
   4 |      40
(4 rows)

ROLLBACK;
-- unreachable WHEN clause should ERROR
BEGIN;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED THEN /* Terminal WHEN clause for MATCHED */
	DELETE
WHEN MATCHED THEN
	UPDATE SET balance = t.balance - s.delta;
ERROR:  unreachable WHEN clause specified after unconditional WHEN clause
ROLLBACK;
-- conditional WHEN clause
CREATE TABLE wq_target (tid integer not null, balance integer DEFAULT -1)
  WITH (autovacuum_enabled=off);
CREATE TABLE wq_source (balance integer, sid integer)
  WITH (autovacuum_enabled=off);
INSERT INTO wq_source (sid, balance) VALUES (1, 100);
BEGIN;
-- try a simple INSERT with default values first
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT (tid) VALUES (s.sid);
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |      -1
(1 row)

ROLLBACK;
-- this time with a FALSE condition
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN NOT MATCHED AND FALSE THEN
	INSERT (tid) VALUES (s.sid);
SELECT * FROM wq_target;
 tid | balance 
-----+---------
(0 rows)

-- this time with an actual condition which returns false
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN NOT MATCHED AND s.balance <> 100 THEN
	INSERT (tid) VALUES (s.sid);
SELECT * FROM wq_target;
 tid | balance 
-----+---------
(0 rows)

BEGIN;
-- and now with a condition which returns true
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN NOT MATCHED AND s.balance = 100 THEN
	INSERT (tid) VALUES (s.sid);
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |      -1
(1 row)

ROLLBACK;
-- conditions in the NOT MATCHED clause can only refer to source columns
BEGIN;
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN NOT MATCHED AND t.balance = 100 THEN
	INSERT (tid) VALUES (s.sid);
ERROR:  invalid reference to FROM-clause entry for table "t"
LINE 3: WHEN NOT MATCHED AND t.balance = 100 THEN
                             ^
DETAIL:  There is an entry for table "t", but it cannot be referenced from this part of the query.
SELECT * FROM wq_target;
ERROR:  current transaction is aborted, commands ignored until end of transaction block
ROLLBACK;
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN NOT MATCHED AND s.balance = 100 THEN
	INSERT (tid) VALUES (s.sid);
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |      -1
(1 row)

-- conditions in NOT MATCHED BY SOURCE clause can only refer to target columns
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN NOT MATCHED BY SOURCE AND s.balance = 100 THEN
	DELETE;
ERROR:  invalid reference to FROM-clause entry for table "s"
LINE 3: WHEN NOT MATCHED BY SOURCE AND s.balance = 100 THEN
                                       ^
DETAIL:  There is an entry for table "s", but it cannot be referenced from this part of the query.
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN NOT MATCHED BY SOURCE AND t.balance = 100 THEN
    DELETE;
-- conditions in MATCHED clause can refer to both source and target
SELECT * FROM wq_source;
 balance | sid 
---------+-----
     100 |   1
(1 row)

MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN MATCHED AND s.balance = 100 THEN
	UPDATE SET balance = t.balance + s.balance;
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |      99
(1 row)

MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN MATCHED AND t.balance = 100 THEN
	UPDATE SET balance = t.balance + s.balance;
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |      99
(1 row)

-- check if AND works
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN MATCHED AND t.balance = 99 AND s.balance > 100 THEN
	UPDATE SET balance = t.balance + s.balance;
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |      99
(1 row)

MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN MATCHED AND t.balance = 99 AND s.balance = 100 THEN
	UPDATE SET balance = t.balance + s.balance;
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |     199
(1 row)

-- check if OR works
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN MATCHED AND t.balance = 99 OR s.balance > 100 THEN
	UPDATE SET balance = t.balance + s.balance;
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |     199
(1 row)

MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN MATCHED AND t.balance = 199 OR s.balance > 100 THEN
	UPDATE SET balance = t.balance + s.balance;
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |     299
(1 row)

-- check source-side whole-row references
BEGIN;
MERGE INTO wq_target t
USING wq_source s ON (t.tid = s.sid)
WHEN matched and t = s or t.tid = s.sid THEN
	UPDATE SET balance = t.balance + s.balance;
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |     399
(1 row)

ROLLBACK;
-- check if subqueries work in the conditions?
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN MATCHED AND t.balance > (SELECT max(balance) FROM target) THEN
	UPDATE SET balance = t.balance + s.balance;
-- check if we can access system columns in the conditions
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN MATCHED AND t.xmin = t.xmax THEN
	UPDATE SET balance = t.balance + s.balance;
ERROR:  cannot use system column "xmin" in MERGE WHEN condition
LINE 3: WHEN MATCHED AND t.xmin = t.xmax THEN
                         ^
MERGE INTO wq_target t
USING wq_source s ON t.tid = s.sid
WHEN MATCHED AND t.tableoid >= 0 THEN
	UPDATE SET balance = t.balance + s.balance;
SELECT * FROM wq_target;
 tid | balance 
-----+---------
   1 |     499
(1 row)

DROP TABLE wq_target, wq_source;
-- test triggers
create or replace function merge_trigfunc () returns trigger
language plpgsql as
$$
DECLARE
	line text;
BEGIN
	SELECT INTO line format('%s %s %s trigger%s',
		TG_WHEN, TG_OP, TG_LEVEL, CASE
		WHEN TG_OP = 'INSERT' AND TG_LEVEL = 'ROW'
			THEN format(' row: %s', NEW)
		WHEN TG_OP = 'UPDATE' AND TG_LEVEL = 'ROW'
			THEN format(' row: %s -> %s', OLD, NEW)
		WHEN TG_OP = 'DELETE' AND TG_LEVEL = 'ROW'
			THEN format(' row: %s', OLD)
		END);

	RAISE NOTICE '%', line;
	IF (TG_WHEN = 'BEFORE' AND TG_LEVEL = 'ROW') THEN
		IF (TG_OP = 'DELETE') THEN
			RETURN OLD;
		ELSE
			RETURN NEW;
		END IF;
	ELSE
		RETURN NULL;
	END IF;
END;
$$;
CREATE TRIGGER merge_bsi BEFORE INSERT ON target FOR EACH STATEMENT EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_bsu BEFORE UPDATE ON target FOR EACH STATEMENT EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_bsd BEFORE DELETE ON target FOR EACH STATEMENT EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_asi AFTER INSERT ON target FOR EACH STATEMENT EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_asu AFTER UPDATE ON target FOR EACH STATEMENT EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_asd AFTER DELETE ON target FOR EACH STATEMENT EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_bri BEFORE INSERT ON target FOR EACH ROW EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_bru BEFORE UPDATE ON target FOR EACH ROW EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_brd BEFORE DELETE ON target FOR EACH ROW EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_ari AFTER INSERT ON target FOR EACH ROW EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_aru AFTER UPDATE ON target FOR EACH ROW EXECUTE PROCEDURE merge_trigfunc ();
CREATE TRIGGER merge_ard AFTER DELETE ON target FOR EACH ROW EXECUTE PROCEDURE merge_trigfunc ();
-- now the classic UPSERT, with a DELETE
BEGIN;
UPDATE target SET balance = 0 WHERE tid = 3;
NOTICE:  BEFORE UPDATE STATEMENT trigger
NOTICE:  BEFORE UPDATE ROW trigger row: (3,30) -> (3,0)
NOTICE:  AFTER UPDATE ROW trigger row: (3,30) -> (3,0)
NOTICE:  AFTER UPDATE STATEMENT trigger
--EXPLAIN (ANALYZE ON, COSTS OFF, SUMMARY OFF, TIMING OFF)
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED AND t.balance > s.delta THEN
	UPDATE SET balance = t.balance - s.delta
WHEN MATCHED THEN
	DELETE
WHEN NOT MATCHED THEN
	INSERT VALUES (s.sid, s.delta);
NOTICE:  BEFORE INSERT STATEMENT trigger
NOTICE:  BEFORE UPDATE STATEMENT trigger
NOTICE:  BEFORE DELETE STATEMENT trigger
NOTICE:  BEFORE DELETE ROW trigger row: (3,0)
NOTICE:  BEFORE UPDATE ROW trigger row: (2,20) -> (2,15)
NOTICE:  BEFORE INSERT ROW trigger row: (4,40)
NOTICE:  AFTER DELETE ROW trigger row: (3,0)
NOTICE:  AFTER UPDATE ROW trigger row: (2,20) -> (2,15)
NOTICE:  AFTER INSERT ROW trigger row: (4,40)
NOTICE:  AFTER DELETE STATEMENT trigger
NOTICE:  AFTER UPDATE STATEMENT trigger
NOTICE:  AFTER INSERT STATEMENT trigger
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      15
   4 |      40
(3 rows)

ROLLBACK;
-- UPSERT with UPDATE/DELETE when not matched by source
BEGIN;
DELETE FROM SOURCE WHERE sid = 2;
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED AND t.balance > s.delta THEN
    UPDATE SET balance = t.balance - s.delta
WHEN MATCHED THEN
	UPDATE SET balance = 0
WHEN NOT MATCHED THEN
    INSERT VALUES (s.sid, s.delta)
WHEN NOT MATCHED BY SOURCE AND tid = 1 THEN
	UPDATE SET balance = 0
WHEN NOT MATCHED BY SOURCE THEN
	DELETE
RETURNING merge_action(), t.*;
NOTICE:  BEFORE INSERT STATEMENT trigger
NOTICE:  BEFORE UPDATE STATEMENT trigger
NOTICE:  BEFORE DELETE STATEMENT trigger
NOTICE:  BEFORE UPDATE ROW trigger row: (3,30) -> (3,10)
NOTICE:  BEFORE INSERT ROW trigger row: (4,40)
NOTICE:  BEFORE DELETE ROW trigger row: (2,20)
NOTICE:  BEFORE UPDATE ROW trigger row: (1,10) -> (1,0)
NOTICE:  AFTER UPDATE ROW trigger row: (3,30) -> (3,10)
NOTICE:  AFTER INSERT ROW trigger row: (4,40)
NOTICE:  AFTER DELETE ROW trigger row: (2,20)
NOTICE:  AFTER UPDATE ROW trigger row: (1,10) -> (1,0)
NOTICE:  AFTER DELETE STATEMENT trigger
NOTICE:  AFTER UPDATE STATEMENT trigger
NOTICE:  AFTER INSERT STATEMENT trigger
 merge_action | tid | balance 
--------------+-----+---------
 UPDATE       |   3 |      10
 INSERT       |   4 |      40
 DELETE       |   2 |      20
 UPDATE       |   1 |       0
(4 rows)

SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |       0
   3 |      10
   4 |      40
(3 rows)

ROLLBACK;
-- Test behavior of triggers that turn UPDATE/DELETE into no-ops
create or replace function skip_merge_op() returns trigger
language plpgsql as
$$
BEGIN
	RETURN NULL;
END;
$$;
SELECT * FROM target full outer join source on (sid = tid);
 tid | balance | sid | delta 
-----+---------+-----+-------
   3 |      30 |   3 |    20
   2 |      20 |   2 |     5
     |         |   4 |    40
   1 |      10 |     |      
(4 rows)

create trigger merge_skip BEFORE INSERT OR UPDATE or DELETE
  ON target FOR EACH ROW EXECUTE FUNCTION skip_merge_op();
DO $$
DECLARE
  result integer;
BEGIN
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED AND s.sid = 3 THEN UPDATE SET balance = t.balance + s.delta
WHEN MATCHED THEN DELETE
WHEN NOT MATCHED THEN INSERT VALUES (sid, delta);
IF FOUND THEN
  RAISE NOTICE 'Found';
ELSE
  RAISE NOTICE 'Not found';
END IF;
GET DIAGNOSTICS result := ROW_COUNT;
RAISE NOTICE 'ROW_COUNT = %', result;
END;
$$;
NOTICE:  BEFORE INSERT STATEMENT trigger
NOTICE:  BEFORE UPDATE STATEMENT trigger
NOTICE:  BEFORE DELETE STATEMENT trigger
NOTICE:  BEFORE UPDATE ROW trigger row: (3,30) -> (3,50)
NOTICE:  BEFORE DELETE ROW trigger row: (2,20)
NOTICE:  BEFORE INSERT ROW trigger row: (4,40)
NOTICE:  AFTER DELETE STATEMENT trigger
NOTICE:  AFTER UPDATE STATEMENT trigger
NOTICE:  AFTER INSERT STATEMENT trigger
NOTICE:  Not found
NOTICE:  ROW_COUNT = 0
SELECT * FROM target FULL OUTER JOIN source ON (sid = tid);
 tid | balance | sid | delta 
-----+---------+-----+-------
   3 |      30 |   3 |    20
   2 |      20 |   2 |     5
     |         |   4 |    40
   1 |      10 |     |      
(4 rows)

DROP TRIGGER merge_skip ON target;
DROP FUNCTION skip_merge_op();
-- test from PL/pgSQL
-- make sure MERGE INTO isn't interpreted to mean returning variables like SELECT INTO
BEGIN;
DO LANGUAGE plpgsql $$
BEGIN
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED AND t.balance > s.delta THEN
	UPDATE SET balance = t.balance - s.delta;
END;
$$;
NOTICE:  BEFORE UPDATE STATEMENT trigger
NOTICE:  BEFORE UPDATE ROW trigger row: (3,30) -> (3,10)
NOTICE:  BEFORE UPDATE ROW trigger row: (2,20) -> (2,15)
NOTICE:  AFTER UPDATE ROW trigger row: (3,30) -> (3,10)
NOTICE:  AFTER UPDATE ROW trigger row: (2,20) -> (2,15)
NOTICE:  AFTER UPDATE STATEMENT trigger
ROLLBACK;
--source constants
BEGIN;
MERGE INTO target t
USING (SELECT 9 AS sid, 57 AS delta) AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT (tid, balance) VALUES (s.sid, s.delta);
NOTICE:  BEFORE INSERT STATEMENT trigger
NOTICE:  BEFORE INSERT ROW trigger row: (9,57)
NOTICE:  AFTER INSERT ROW trigger row: (9,57)
NOTICE:  AFTER INSERT STATEMENT trigger
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
   9 |      57
(4 rows)

ROLLBACK;
--source query
BEGIN;
MERGE INTO target t
USING (SELECT sid, delta FROM source WHERE delta > 0) AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT (tid, balance) VALUES (s.sid, s.delta);
NOTICE:  BEFORE INSERT STATEMENT trigger
NOTICE:  BEFORE INSERT ROW trigger row: (4,40)
NOTICE:  AFTER INSERT ROW trigger row: (4,40)
NOTICE:  AFTER INSERT STATEMENT trigger
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
   4 |      40
(4 rows)

ROLLBACK;
BEGIN;
MERGE INTO target t
USING (SELECT sid, delta as newname FROM source WHERE delta > 0) AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT (tid, balance) VALUES (s.sid, s.newname);
NOTICE:  BEFORE INSERT STATEMENT trigger
NOTICE:  BEFORE INSERT ROW trigger row: (4,40)
NOTICE:  AFTER INSERT ROW trigger row: (4,40)
NOTICE:  AFTER INSERT STATEMENT trigger
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
   4 |      40
(4 rows)

ROLLBACK;
--self-merge
BEGIN;
MERGE INTO target t1
USING target t2
ON t1.tid = t2.tid
WHEN MATCHED THEN
	UPDATE SET balance = t1.balance + t2.balance
WHEN NOT MATCHED THEN
	INSERT VALUES (t2.tid, t2.balance);
NOTICE:  BEFORE INSERT STATEMENT trigger
NOTICE:  BEFORE UPDATE STATEMENT trigger
NOTICE:  BEFORE UPDATE ROW trigger row: (1,10) -> (1,20)
NOTICE:  BEFORE UPDATE ROW trigger row: (2,20) -> (2,40)
NOTICE:  BEFORE UPDATE ROW trigger row: (3,30) -> (3,60)
NOTICE:  AFTER UPDATE ROW trigger row: (1,10) -> (1,20)
NOTICE:  AFTER UPDATE ROW trigger row: (2,20) -> (2,40)
NOTICE:  AFTER UPDATE ROW trigger row: (3,30) -> (3,60)
NOTICE:  AFTER UPDATE STATEMENT trigger
NOTICE:  AFTER INSERT STATEMENT trigger
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      20
   2 |      40
   3 |      60
(3 rows)

ROLLBACK;
BEGIN;
MERGE INTO target t
USING (SELECT tid as sid, balance as delta FROM target WHERE balance > 0) AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT (tid, balance) VALUES (s.sid, s.delta);
NOTICE:  BEFORE INSERT STATEMENT trigger
NOTICE:  AFTER INSERT STATEMENT trigger
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
(3 rows)

ROLLBACK;
BEGIN;
MERGE INTO target t
USING
(SELECT sid, max(delta) AS delta
 FROM source
 GROUP BY sid
 HAVING count(*) = 1
 ORDER BY sid ASC) AS s
ON t.tid = s.sid
WHEN NOT MATCHED THEN
	INSERT (tid, balance) VALUES (s.sid, s.delta);
NOTICE:  BEFORE INSERT STATEMENT trigger
NOTICE:  BEFORE INSERT ROW trigger row: (4,40)
NOTICE:  AFTER INSERT ROW trigger row: (4,40)
NOTICE:  AFTER INSERT STATEMENT trigger
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      30
   4 |      40
(4 rows)

ROLLBACK;
-- plpgsql parameters and results
BEGIN;
CREATE FUNCTION merge_func (p_id integer, p_bal integer)
RETURNS INTEGER
LANGUAGE plpgsql
AS $$
DECLARE
 result integer;
BEGIN
MERGE INTO target t
USING (SELECT p_id AS sid) AS s
ON t.tid = s.sid
WHEN MATCHED THEN
	UPDATE SET balance = t.balance - p_bal;
IF FOUND THEN
	GET DIAGNOSTICS result := ROW_COUNT;
END IF;
RETURN result;
END;
$$;
SELECT merge_func(3, 4);
NOTICE:  BEFORE UPDATE STATEMENT trigger
NOTICE:  BEFORE UPDATE ROW trigger row: (3,30) -> (3,26)
NOTICE:  AFTER UPDATE ROW trigger row: (3,30) -> (3,26)
NOTICE:  AFTER UPDATE STATEMENT trigger
 merge_func 
------------
          1
(1 row)

SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |      10
   2 |      20
   3 |      26
(3 rows)

ROLLBACK;
-- PREPARE
BEGIN;
prepare foom as merge into target t using (select 1 as sid) s on (t.tid = s.sid) when matched then update set balance = 1;
execute foom;
NOTICE:  BEFORE UPDATE STATEMENT trigger
NOTICE:  BEFORE UPDATE ROW trigger row: (1,10) -> (1,1)
NOTICE:  AFTER UPDATE ROW trigger row: (1,10) -> (1,1)
NOTICE:  AFTER UPDATE STATEMENT trigger
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |       1
   2 |      20
   3 |      30
(3 rows)

ROLLBACK;
BEGIN;
PREPARE foom2 (integer, integer) AS
MERGE INTO target t
USING (SELECT 1) s
ON t.tid = $1
WHEN MATCHED THEN
UPDATE SET balance = $2;
--EXPLAIN (ANALYZE ON, COSTS OFF, SUMMARY OFF, TIMING OFF)
execute foom2 (1, 1);
NOTICE:  BEFORE UPDATE STATEMENT trigger
NOTICE:  BEFORE UPDATE ROW trigger row: (1,10) -> (1,1)
NOTICE:  AFTER UPDATE ROW trigger row: (1,10) -> (1,1)
NOTICE:  AFTER UPDATE STATEMENT trigger
SELECT * FROM target ORDER BY tid;
 tid | balance 
-----+---------
   1 |       1
   2 |      20
   3 |      30
(3 rows)

ROLLBACK;
-- subqueries in source relation
CREATE TABLE sq_target (tid integer NOT NULL, balance integer)
  WITH (autovacuum_enabled=off);
CREATE TABLE sq_source (delta integer, sid integer, balance integer DEFAULT 0)
  WITH (autovacuum_enabled=off);
INSERT INTO sq_target(tid, balance) VALUES (1,100), (2,200), (3,300);
INSERT INTO sq_source(sid, delta) VALUES (1,10), (2,20), (4,40);
BEGIN;
MERGE INTO sq_target t
USING (SELECT * FROM sq_source) s
ON tid = sid
WHEN MATCHED AND t.balance > delta THEN
	UPDATE SET balance = t.balance + delta;
SELECT * FROM sq_target;
 tid | balance 
-----+---------
   3 |     300
   1 |     110
   2 |     220
(3 rows)

ROLLBACK;
-- try a view
CREATE VIEW v AS SELECT * FROM sq_source WHERE sid < 2;
BEGIN;
MERGE INTO sq_target
USING v
ON tid = sid
WHEN MATCHED THEN
    UPDATE SET balance = v.balance + delta;
SELECT * FROM sq_target;
 tid | balance 
-----+---------
   2 |     200
   3 |     300
   1 |      10
(3 rows)

ROLLBACK;
-- ambiguous reference to a column
BEGIN;
MERGE INTO sq_target
USING v
ON tid = sid
WHEN MATCHED AND tid >= 2 THEN
    UPDATE SET balance = balance + delta
WHEN NOT MATCHED THEN
	INSERT (balance, tid) VALUES (balance + delta, sid)
WHEN MATCHED AND tid < 2 THEN
	DELETE;
ERROR:  column reference "balance" is ambiguous
LINE 5:     UPDATE SET balance = balance + delta
                                 ^
ROLLBACK;
BEGIN;
INSERT INTO sq_source (sid, balance, delta) VALUES (-1, -1, -10);
MERGE INTO sq_target t
USING v
ON tid = sid
WHEN MATCHED AND tid >= 2 THEN
    UPDATE SET balance = t.balance + delta
WHEN NOT MATCHED THEN
	INSERT (balance, tid) VALUES (balance + delta, sid)
WHEN MATCHED AND tid < 2 THEN
	DELETE;
SELECT * FROM sq_target;
 tid | balance 
-----+---------
   2 |     200
   3 |     300
  -1 |     -11
(3 rows)

ROLLBACK;
-- CTEs
BEGIN;
INSERT INTO sq_source (sid, balance, delta) VALUES (-1, -1, -10);
WITH targq AS (
	SELECT * FROM v
)
MERGE INTO sq_target t
USING v
ON tid = sid
WHEN MATCHED AND tid >= 2 THEN
    UPDATE SET balance = t.balance + delta
WHEN NOT MATCHED THEN
	INSERT (balance, tid) VALUES (balance + delta, sid)
WHEN MATCHED AND tid < 2 THEN
	DELETE;
ROLLBACK;
-- RETURNING
SELECT * FROM sq_source ORDER BY sid;
 delta | sid | balance 
-------+-----+---------
    10 |   1 |       0
    20 |   2 |       0
    40 |   4 |       0
(3 rows)

SELECT * FROM sq_target ORDER BY tid;
 tid | balance 
-----+---------
   1 |     100
   2 |     200
   3 |     300
(3 rows)

BEGIN;
CREATE TABLE merge_actions(action text, abbrev text);
INSERT INTO merge_actions VALUES ('INSERT', 'ins'), ('UPDATE', 'upd'), ('DELETE', 'del');
MERGE INTO sq_target t
USING sq_source s
ON tid = sid
WHEN MATCHED AND tid >= 2 THEN
    UPDATE SET balance = t.balance + delta
WHEN NOT MATCHED THEN
    INSERT (balance, tid) VALUES (balance + delta, sid)
WHEN MATCHED AND tid < 2 THEN
    DELETE
RETURNING (SELECT abbrev FROM merge_actions
            WHERE action = merge_action()) AS action,
          t.*,
          CASE merge_action()
              WHEN 'INSERT' THEN 'Inserted '||t
              WHEN 'UPDATE' THEN 'Added '||delta||' to balance'
              WHEN 'DELETE' THEN 'Removed '||t
          END AS description;
 action | tid | balance |     description     
--------+-----+---------+---------------------
 del    |   1 |     100 | Removed (1,100)
 upd    |   2 |     220 | Added 20 to balance
 ins    |   4 |      40 | Inserted (4,40)
(3 rows)

ROLLBACK;
-- error when using merge_action() outside MERGE
SELECT merge_action() FROM sq_target;
ERROR:  MERGE_ACTION() can only be used in the RETURNING list of a MERGE command
LINE 1: SELECT merge_action() FROM sq_target;
               ^
UPDATE sq_target SET balance = balance + 1 RETURNING merge_action();
ERROR:  MERGE_ACTION() can only be used in the RETURNING list of a MERGE command
LINE 1: ...ATE sq_target SET balance = balance + 1 RETURNING merge_acti...
                                                             ^
-- RETURNING in CTEs
CREATE TABLE sq_target_merge_log (tid integer NOT NULL, last_change text);
INSERT INTO sq_target_merge_log VALUES (1, 'Original value');
BEGIN;
WITH m AS (
    MERGE INTO sq_target t
    USING sq_source s
    ON tid = sid
    WHEN MATCHED AND tid >= 2 THEN
        UPDATE SET balance = t.balance + delta
    WHEN NOT MATCHED THEN
        INSERT (balance, tid) VALUES (balance + delta, sid)
    WHEN MATCHED AND tid < 2 THEN
        DELETE
    RETURNING merge_action() AS action, t.*,
              CASE merge_action()
                  WHEN 'INSERT' THEN 'Inserted '||t
                  WHEN 'UPDATE' THEN 'Added '||delta||' to balance'
                  WHEN 'DELETE' THEN 'Removed '||t
              END AS description
), m2 AS (
    MERGE INTO sq_target_merge_log l
    USING m
    ON l.tid = m.tid
    WHEN MATCHED THEN
        UPDATE SET last_change = description
    WHEN NOT MATCHED THEN
        INSERT VALUES (m.tid, description)
    RETURNING action, merge_action() AS log_action, l.*
)
SELECT * FROM m2;
 action | log_action | tid |     last_change     
--------+------------+-----+---------------------
 DELETE | UPDATE     |   1 | Removed (1,100)
 UPDATE | INSERT     |   2 | Added 20 to balance
 INSERT | INSERT     |   4 | Inserted (4,40)
(3 rows)

SELECT * FROM sq_target_merge_log ORDER BY tid;
 tid |     last_change     
-----+---------------------
   1 | Removed (1,100)
   2 | Added 20 to balance
   4 | Inserted (4,40)
(3 rows)

ROLLBACK;
-- COPY (MERGE ... RETURNING) TO ...
BEGIN;
COPY (
    MERGE INTO sq_target t
    USING sq_source s
    ON tid = sid
    WHEN MATCHED AND tid >= 2 THEN
        UPDATE SET balance = t.balance + delta
    WHEN NOT MATCHED THEN
        INSERT (balance, tid) VALUES (balance + delta, sid)
    WHEN MATCHED AND tid < 2 THEN
        DELETE
    RETURNING merge_action(), t.*
) TO stdout;
DELETE	1	100
UPDATE	2	220
INSERT	4	40
ROLLBACK;
-- SQL function with MERGE ... RETURNING
BEGIN;
CREATE FUNCTION merge_into_sq_target(sid int, balance int, delta int,
                                     OUT action text, OUT tid int, OUT new_balance int)
LANGUAGE sql AS
$$
    MERGE INTO sq_target t
    USING (VALUES ($1, $2, $3)) AS v(sid, balance, delta)
    ON tid = v.sid
    WHEN MATCHED AND tid >= 2 THEN
        UPDATE SET balance = t.balance + v.delta
    WHEN NOT MATCHED THEN
        INSERT (balance, tid) VALUES (v.balance + v.delta, v.sid)
    WHEN MATCHED AND tid < 2 THEN
        DELETE
    RETURNING merge_action(), t.*;
$$;
SELECT m.*
FROM (VALUES (1, 0, 0), (3, 0, 20), (4, 100, 10)) AS v(sid, balance, delta),
LATERAL (SELECT action, tid, new_balance FROM merge_into_sq_target(sid, balance, delta)) m;
 action | tid | new_balance 
--------+-----+-------------
 DELETE |   1 |         100
 UPDATE |   3 |         320
 INSERT |   4 |         110
(3 rows)

ROLLBACK;
-- SQL SRF with MERGE ... RETURNING
BEGIN;
CREATE FUNCTION merge_sq_source_into_sq_target()
RETURNS TABLE (action text, tid int, balance int)
LANGUAGE sql AS
$$
    MERGE INTO sq_target t
    USING sq_source s
    ON tid = sid
    WHEN MATCHED AND tid >= 2 THEN
        UPDATE SET balance = t.balance + delta
    WHEN NOT MATCHED THEN
        INSERT (balance, tid) VALUES (balance + delta, sid)
    WHEN MATCHED AND tid < 2 THEN
        DELETE
    RETURNING merge_action(), t.*;
$$;
SELECT * FROM merge_sq_source_into_sq_target();
 action | tid | balance 
--------+-----+---------
 DELETE |   1 |     100
 UPDATE |   2 |     220
 INSERT |   4 |      40
(3 rows)

ROLLBACK;
-- PL/pgSQL function with MERGE ... RETURNING ... INTO
BEGIN;
CREATE FUNCTION merge_into_sq_target(sid int, balance int, delta int,
                                     OUT r_action text, OUT r_tid int, OUT r_balance int)
LANGUAGE plpgsql AS
$$
BEGIN
    MERGE INTO sq_target t
    USING (VALUES ($1, $2, $3)) AS v(sid, balance, delta)
    ON tid = v.sid
    WHEN MATCHED AND tid >= 2 THEN
        UPDATE SET balance = t.balance + v.delta
    WHEN NOT MATCHED THEN
        INSERT (balance, tid) VALUES (v.balance + v.delta, v.sid)
    WHEN MATCHED AND tid < 2 THEN
        DELETE
    RETURNING merge_action(), t.* INTO r_action, r_tid, r_balance;
END;
$$;
SELECT m.*
FROM (VALUES (1, 0, 0), (3, 0, 20), (4, 100, 10)) AS v(sid, balance, delta),
LATERAL (SELECT r_action, r_tid, r_balance FROM merge_into_sq_target(sid, balance, delta)) m;
 r_action | r_tid | r_balance 
----------+-------+-----------
 DELETE   |     1 |       100
 UPDATE   |     3 |       320
 INSERT   |     4 |       110
(3 rows)

ROLLBACK;
-- EXPLAIN
CREATE TABLE ex_mtarget (a int, b int)
  WITH (autovacuum_enabled=off);
CREATE TABLE ex_msource (a int, b int)
  WITH (autovacuum_enabled=off);
INSERT INTO ex_mtarget SELECT i, i*10 FROM generate_series(1,100,2) i;
INSERT INTO ex_msource SELECT i, i*10 FROM generate_series(1,100,1) i;
CREATE FUNCTION explain_merge(query text) RETURNS SETOF text
LANGUAGE plpgsql AS
$$
DECLARE ln text;
BEGIN
    FOR ln IN
        EXECUTE 'explain (analyze, timing off, summary off, costs off) ' ||
		  query
    LOOP
        ln := regexp_replace(ln, '(Memory( Usage)?|Buckets|Batches): \S*',  '\1: xxx', 'g');
        RETURN NEXT ln;
    END LOOP;
END;
$$;
-- only updates
SELECT explain_merge('
MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a
WHEN MATCHED THEN
	UPDATE SET b = t.b + 1');
                            explain_merge                             
----------------------------------------------------------------------
 Merge on ex_mtarget t (actual rows=0 loops=1)
   Tuples: updated=50
   ->  Merge Join (actual rows=50 loops=1)
         Merge Cond: (t.a = s.a)
         ->  Sort (actual rows=50 loops=1)
               Sort Key: t.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_mtarget t (actual rows=50 loops=1)
         ->  Sort (actual rows=100 loops=1)
               Sort Key: s.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_msource s (actual rows=100 loops=1)
(12 rows)

-- only updates to selected tuples
SELECT explain_merge('
MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a
WHEN MATCHED AND t.a < 10 THEN
	UPDATE SET b = t.b + 1');
                            explain_merge                             
----------------------------------------------------------------------
 Merge on ex_mtarget t (actual rows=0 loops=1)
   Tuples: updated=5 skipped=45
   ->  Merge Join (actual rows=50 loops=1)
         Merge Cond: (t.a = s.a)
         ->  Sort (actual rows=50 loops=1)
               Sort Key: t.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_mtarget t (actual rows=50 loops=1)
         ->  Sort (actual rows=100 loops=1)
               Sort Key: s.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_msource s (actual rows=100 loops=1)
(12 rows)

-- updates + deletes
SELECT explain_merge('
MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a
WHEN MATCHED AND t.a < 10 THEN
	UPDATE SET b = t.b + 1
WHEN MATCHED AND t.a >= 10 AND t.a <= 20 THEN
	DELETE');
                            explain_merge                             
----------------------------------------------------------------------
 Merge on ex_mtarget t (actual rows=0 loops=1)
   Tuples: updated=5 deleted=5 skipped=40
   ->  Merge Join (actual rows=50 loops=1)
         Merge Cond: (t.a = s.a)
         ->  Sort (actual rows=50 loops=1)
               Sort Key: t.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_mtarget t (actual rows=50 loops=1)
         ->  Sort (actual rows=100 loops=1)
               Sort Key: s.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_msource s (actual rows=100 loops=1)
(12 rows)

-- only inserts
SELECT explain_merge('
MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a
WHEN NOT MATCHED AND s.a < 10 THEN
	INSERT VALUES (a, b)');
                            explain_merge                             
----------------------------------------------------------------------
 Merge on ex_mtarget t (actual rows=0 loops=1)
   Tuples: inserted=4 skipped=96
   ->  Merge Left Join (actual rows=100 loops=1)
         Merge Cond: (s.a = t.a)
         ->  Sort (actual rows=100 loops=1)
               Sort Key: s.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_msource s (actual rows=100 loops=1)
         ->  Sort (actual rows=45 loops=1)
               Sort Key: t.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_mtarget t (actual rows=45 loops=1)
(12 rows)

-- all three
SELECT explain_merge('
MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a
WHEN MATCHED AND t.a < 10 THEN
	UPDATE SET b = t.b + 1
WHEN MATCHED AND t.a >= 30 AND t.a <= 40 THEN
	DELETE
WHEN NOT MATCHED AND s.a < 20 THEN
	INSERT VALUES (a, b)');
                            explain_merge                             
----------------------------------------------------------------------
 Merge on ex_mtarget t (actual rows=0 loops=1)
   Tuples: inserted=10 updated=9 deleted=5 skipped=76
   ->  Merge Left Join (actual rows=100 loops=1)
         Merge Cond: (s.a = t.a)
         ->  Sort (actual rows=100 loops=1)
               Sort Key: s.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_msource s (actual rows=100 loops=1)
         ->  Sort (actual rows=49 loops=1)
               Sort Key: t.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_mtarget t (actual rows=49 loops=1)
(12 rows)

-- not matched by source
SELECT explain_merge('
MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a
WHEN NOT MATCHED BY SOURCE and t.a < 10 THEN
	DELETE');
                            explain_merge                             
----------------------------------------------------------------------
 Merge on ex_mtarget t (actual rows=0 loops=1)
   Tuples: skipped=54
   ->  Merge Left Join (actual rows=54 loops=1)
         Merge Cond: (t.a = s.a)
         ->  Sort (actual rows=54 loops=1)
               Sort Key: t.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_mtarget t (actual rows=54 loops=1)
         ->  Sort (actual rows=100 loops=1)
               Sort Key: s.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_msource s (actual rows=100 loops=1)
(12 rows)

-- not matched by source and target
SELECT explain_merge('
MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a
WHEN NOT MATCHED BY SOURCE AND t.a < 10 THEN
	DELETE
WHEN NOT MATCHED BY TARGET AND s.a < 20 THEN
	INSERT VALUES (a, b)');
                            explain_merge                             
----------------------------------------------------------------------
 Merge on ex_mtarget t (actual rows=0 loops=1)
   Tuples: skipped=100
   ->  Merge Full Join (actual rows=100 loops=1)
         Merge Cond: (t.a = s.a)
         ->  Sort (actual rows=54 loops=1)
               Sort Key: t.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_mtarget t (actual rows=54 loops=1)
         ->  Sort (actual rows=100 loops=1)
               Sort Key: s.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_msource s (actual rows=100 loops=1)
(12 rows)

-- nothing
SELECT explain_merge('
MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a AND t.a < -1000
WHEN MATCHED AND t.a < 10 THEN
	DO NOTHING');
                           explain_merge                            
--------------------------------------------------------------------
 Merge on ex_mtarget t (actual rows=0 loops=1)
   ->  Merge Join (actual rows=0 loops=1)
         Merge Cond: (t.a = s.a)
         ->  Sort (actual rows=0 loops=1)
               Sort Key: t.a
               Sort Method: quicksort  Memory: xxx
               ->  Seq Scan on ex_mtarget t (actual rows=0 loops=1)
                     Filter: (a < '-1000'::integer)
                     Rows Removed by Filter: 54
         ->  Sort (never executed)
               Sort Key: s.a
               ->  Seq Scan on ex_msource s (never executed)
(12 rows)

DROP TABLE ex_msource, ex_mtarget;
DROP FUNCTION explain_merge(text);
-- EXPLAIN SubPlans and InitPlans
CREATE TABLE src (a int, b int, c int, d int);
CREATE TABLE tgt (a int, b int, c int, d int);
CREATE TABLE ref (ab int, cd int);
EXPLAIN (verbose, costs off)
MERGE INTO tgt t
USING (SELECT *, (SELECT count(*) FROM ref r
                   WHERE r.ab = s.a + s.b
                     AND r.cd = s.c - s.d) cnt
         FROM src s) s
ON t.a = s.a AND t.b < s.cnt
WHEN MATCHED AND t.c > s.cnt THEN
  UPDATE SET (b, c) = (SELECT s.b, s.cnt);
                                     QUERY PLAN                                      
-------------------------------------------------------------------------------------
 Merge on public.tgt t
   ->  Hash Join
         Output: t.ctid, s.a, s.b, s.c, s.d, s.ctid
         Hash Cond: (t.a = s.a)
         Join Filter: (t.b < (SubPlan 1))
         ->  Seq Scan on public.tgt t
               Output: t.ctid, t.a, t.b
         ->  Hash
               Output: s.a, s.b, s.c, s.d, s.ctid
               ->  Seq Scan on public.src s
                     Output: s.a, s.b, s.c, s.d, s.ctid
         SubPlan 1
           ->  Aggregate
                 Output: count(*)
                 ->  Seq Scan on public.ref r
                       Output: r.ab, r.cd
                       Filter: ((r.ab = (s.a + s.b)) AND (r.cd = (s.c - s.d)))
   SubPlan 4
     ->  Aggregate
           Output: count(*)
           ->  Seq Scan on public.ref r_2
                 Output: r_2.ab, r_2.cd
                 Filter: ((r_2.ab = (s.a + s.b)) AND (r_2.cd = (s.c - s.d)))
   SubPlan 3
     ->  Result
           Output: s.b, (InitPlan 2).col1
           InitPlan 2
             ->  Aggregate
                   Output: count(*)
                   ->  Seq Scan on public.ref r_1
                         Output: r_1.ab, r_1.cd
                         Filter: ((r_1.ab = (s.a + s.b)) AND (r_1.cd = (s.c - s.d)))
(32 rows)

DROP TABLE src, tgt, ref;
-- Subqueries
BEGIN;
MERGE INTO sq_target t
USING v
ON tid = sid
WHEN MATCHED THEN
    UPDATE SET balance = (SELECT count(*) FROM sq_target);
SELECT * FROM sq_target WHERE tid = 1;
 tid | balance 
-----+---------
   1 |       3
(1 row)

ROLLBACK;
BEGIN;
MERGE INTO sq_target t
USING v
ON tid = sid
WHEN MATCHED AND (SELECT count(*) > 0 FROM sq_target) THEN
    UPDATE SET balance = 42;
SELECT * FROM sq_target WHERE tid = 1;
 tid | balance 
-----+---------
   1 |      42
(1 row)

ROLLBACK;
BEGIN;
MERGE INTO sq_target t
USING v
ON tid = sid AND (SELECT count(*) > 0 FROM sq_target)
WHEN MATCHED THEN
    UPDATE SET balance = 42;
SELECT * FROM sq_target WHERE tid = 1;
 tid | balance 
-----+---------
   1 |      42
(1 row)

ROLLBACK;
DROP TABLE sq_target, sq_target_merge_log, sq_source CASCADE;
NOTICE:  drop cascades to view v
CREATE TABLE pa_target (tid integer, balance float, val text)
	PARTITION BY LIST (tid);
CREATE TABLE part1 PARTITION OF pa_target FOR VALUES IN (1,4)
  WITH (autovacuum_enabled=off);
CREATE TABLE part2 PARTITION OF pa_target FOR VALUES IN (2,5,6)
  WITH (autovacuum_enabled=off);
CREATE TABLE part3 PARTITION OF pa_target FOR VALUES IN (3,8,9)
  WITH (autovacuum_enabled=off);
CREATE TABLE part4 PARTITION OF pa_target DEFAULT
  WITH (autovacuum_enabled=off);
CREATE TABLE pa_source (sid integer, delta float);
-- insert many rows to the source table
INSERT INTO pa_source SELECT id, id * 10  FROM generate_series(1,14) AS id;
-- insert a few rows in the target table (odd numbered tid)
INSERT INTO pa_target SELECT id, id * 100, 'initial' FROM generate_series(1,15,2) AS id;
-- try simple MERGE
BEGIN;
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid
  WHEN MATCHED THEN
    UPDATE SET balance = balance + delta, val = val || ' updated by merge'
  WHEN NOT MATCHED THEN
    INSERT VALUES (sid, delta, 'inserted by merge')
  WHEN NOT MATCHED BY SOURCE THEN
    UPDATE SET val = val || ' not matched by source';
SELECT * FROM pa_target ORDER BY tid, val;
 tid | balance |              val              
-----+---------+-------------------------------
   1 |     110 | initial updated by merge
   2 |      20 | inserted by merge
   3 |     330 | initial updated by merge
   4 |      40 | inserted by merge
   5 |     550 | initial updated by merge
   6 |      60 | inserted by merge
   7 |     770 | initial updated by merge
   8 |      80 | inserted by merge
   9 |     990 | initial updated by merge
  10 |     100 | inserted by merge
  11 |    1210 | initial updated by merge
  12 |     120 | inserted by merge
  13 |    1430 | initial updated by merge
  14 |     140 | inserted by merge
  15 |    1500 | initial not matched by source
(15 rows)

ROLLBACK;
-- same with a constant qual
BEGIN;
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid AND tid = 1
  WHEN MATCHED THEN
    UPDATE SET balance = balance + delta, val = val || ' updated by merge'
  WHEN NOT MATCHED THEN
    INSERT VALUES (sid, delta, 'inserted by merge')
  WHEN NOT MATCHED BY SOURCE THEN
    UPDATE SET val = val || ' not matched by source';
SELECT * FROM pa_target ORDER BY tid, val;
 tid | balance |              val              
-----+---------+-------------------------------
   1 |     110 | initial updated by merge
   2 |      20 | inserted by merge
   3 |     300 | initial not matched by source
   3 |      30 | inserted by merge
   4 |      40 | inserted by merge
   5 |     500 | initial not matched by source
   5 |      50 | inserted by merge
   6 |      60 | inserted by merge
   7 |     700 | initial not matched by source
   7 |      70 | inserted by merge
   8 |      80 | inserted by merge
   9 |     900 | initial not matched by source
   9 |      90 | inserted by merge
  10 |     100 | inserted by merge
  11 |    1100 | initial not matched by source
  11 |     110 | inserted by merge
  12 |     120 | inserted by merge
  13 |    1300 | initial not matched by source
  13 |     130 | inserted by merge
  14 |     140 | inserted by merge
  15 |    1500 | initial not matched by source
(21 rows)

ROLLBACK;
-- try updating the partition key column
BEGIN;
CREATE FUNCTION merge_func() RETURNS integer LANGUAGE plpgsql AS $$
DECLARE
  result integer;
BEGIN
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid
  WHEN MATCHED THEN
    UPDATE SET tid = tid + 1, balance = balance + delta, val = val || ' updated by merge'
  WHEN NOT MATCHED THEN
    INSERT VALUES (sid, delta, 'inserted by merge')
  WHEN NOT MATCHED BY SOURCE THEN
    UPDATE SET tid = 1, val = val || ' not matched by source';
IF FOUND THEN
  GET DIAGNOSTICS result := ROW_COUNT;
END IF;
RETURN result;
END;
$$;
SELECT merge_func();
 merge_func 
------------
         15
(1 row)

SELECT * FROM pa_target ORDER BY tid, val;
 tid | balance |              val              
-----+---------+-------------------------------
   1 |    1500 | initial not matched by source
   2 |     110 | initial updated by merge
   2 |      20 | inserted by merge
   4 |     330 | initial updated by merge
   4 |      40 | inserted by merge
   6 |     550 | initial updated by merge
   6 |      60 | inserted by merge
   8 |     770 | initial updated by merge
   8 |      80 | inserted by merge
  10 |     990 | initial updated by merge
  10 |     100 | inserted by merge
  12 |    1210 | initial updated by merge
  12 |     120 | inserted by merge
  14 |    1430 | initial updated by merge
  14 |     140 | inserted by merge
(15 rows)

ROLLBACK;
-- update partition key to partition not initially scanned
BEGIN;
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid AND t.tid = 1
  WHEN MATCHED THEN
    UPDATE SET tid = tid + 1, balance = balance + delta, val = val || ' updated by merge'
  RETURNING merge_action(), t.*;
 merge_action | tid | balance |           val            
--------------+-----+---------+--------------------------
 UPDATE       |   2 |     110 | initial updated by merge
(1 row)

SELECT * FROM pa_target ORDER BY tid;
 tid | balance |           val            
-----+---------+--------------------------
   2 |     110 | initial updated by merge
   3 |     300 | initial
   5 |     500 | initial
   7 |     700 | initial
   9 |     900 | initial
  11 |    1100 | initial
  13 |    1300 | initial
  15 |    1500 | initial
(8 rows)

ROLLBACK;
DROP TABLE pa_target CASCADE;
-- The target table is partitioned in the same way, but this time by attaching
-- partitions which have columns in different order, dropped columns etc.
CREATE TABLE pa_target (tid integer, balance float, val text)
	PARTITION BY LIST (tid);
CREATE TABLE part1 (tid integer, balance float, val text)
  WITH (autovacuum_enabled=off);
CREATE TABLE part2 (balance float, tid integer, val text)
  WITH (autovacuum_enabled=off);
CREATE TABLE part3 (tid integer, balance float, val text)
  WITH (autovacuum_enabled=off);
CREATE TABLE part4 (extraid text, tid integer, balance float, val text)
  WITH (autovacuum_enabled=off);
ALTER TABLE part4 DROP COLUMN extraid;
ALTER TABLE pa_target ATTACH PARTITION part1 FOR VALUES IN (1,4);
ALTER TABLE pa_target ATTACH PARTITION part2 FOR VALUES IN (2,5,6);
ALTER TABLE pa_target ATTACH PARTITION part3 FOR VALUES IN (3,8,9);
ALTER TABLE pa_target ATTACH PARTITION part4 DEFAULT;
-- insert a few rows in the target table (odd numbered tid)
INSERT INTO pa_target SELECT id, id * 100, 'initial' FROM generate_series(1,15,2) AS id;
-- try simple MERGE
BEGIN;
DO $$
DECLARE
  result integer;
BEGIN
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid
  WHEN MATCHED THEN
    UPDATE SET balance = balance + delta, val = val || ' updated by merge'
  WHEN NOT MATCHED THEN
    INSERT VALUES (sid, delta, 'inserted by merge')
  WHEN NOT MATCHED BY SOURCE THEN
    UPDATE SET val = val || ' not matched by source';
GET DIAGNOSTICS result := ROW_COUNT;
RAISE NOTICE 'ROW_COUNT = %', result;
END;
$$;
NOTICE:  ROW_COUNT = 15
SELECT * FROM pa_target ORDER BY tid, val;
 tid | balance |              val              
-----+---------+-------------------------------
   1 |     110 | initial updated by merge
   2 |      20 | inserted by merge
   3 |     330 | initial updated by merge
   4 |      40 | inserted by merge
   5 |     550 | initial updated by merge
   6 |      60 | inserted by merge
   7 |     770 | initial updated by merge
   8 |      80 | inserted by merge
   9 |     990 | initial updated by merge
  10 |     100 | inserted by merge
  11 |    1210 | initial updated by merge
  12 |     120 | inserted by merge
  13 |    1430 | initial updated by merge
  14 |     140 | inserted by merge
  15 |    1500 | initial not matched by source
(15 rows)

ROLLBACK;
-- same with a constant qual
BEGIN;
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid AND tid IN (1, 5)
  WHEN MATCHED AND tid % 5 = 0 THEN DELETE
  WHEN MATCHED THEN
    UPDATE SET balance = balance + delta, val = val || ' updated by merge'
  WHEN NOT MATCHED THEN
    INSERT VALUES (sid, delta, 'inserted by merge')
  WHEN NOT MATCHED BY SOURCE THEN
    UPDATE SET val = val || ' not matched by source';
SELECT * FROM pa_target ORDER BY tid, val;
 tid | balance |              val              
-----+---------+-------------------------------
   1 |     110 | initial updated by merge
   2 |      20 | inserted by merge
   3 |     300 | initial not matched by source
   3 |      30 | inserted by merge
   4 |      40 | inserted by merge
   6 |      60 | inserted by merge
   7 |     700 | initial not matched by source
   7 |      70 | inserted by merge
   8 |      80 | inserted by merge
   9 |     900 | initial not matched by source
   9 |      90 | inserted by merge
  10 |     100 | inserted by merge
  11 |    1100 | initial not matched by source
  11 |     110 | inserted by merge
  12 |     120 | inserted by merge
  13 |    1300 | initial not matched by source
  13 |     130 | inserted by merge
  14 |     140 | inserted by merge
  15 |    1500 | initial not matched by source
(19 rows)

ROLLBACK;
-- try updating the partition key column
BEGIN;
DO $$
DECLARE
  result integer;
BEGIN
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid
  WHEN MATCHED THEN
    UPDATE SET tid = tid + 1, balance = balance + delta, val = val || ' updated by merge'
  WHEN NOT MATCHED THEN
    INSERT VALUES (sid, delta, 'inserted by merge')
  WHEN NOT MATCHED BY SOURCE THEN
    UPDATE SET tid = 1, val = val || ' not matched by source';
GET DIAGNOSTICS result := ROW_COUNT;
RAISE NOTICE 'ROW_COUNT = %', result;
END;
$$;
NOTICE:  ROW_COUNT = 15
SELECT * FROM pa_target ORDER BY tid, val;
 tid | balance |              val              
-----+---------+-------------------------------
   1 |    1500 | initial not matched by source
   2 |     110 | initial updated by merge
   2 |      20 | inserted by merge
   4 |     330 | initial updated by merge
   4 |      40 | inserted by merge
   6 |     550 | initial updated by merge
   6 |      60 | inserted by merge
   8 |     770 | initial updated by merge
   8 |      80 | inserted by merge
  10 |     990 | initial updated by merge
  10 |     100 | inserted by merge
  12 |    1210 | initial updated by merge
  12 |     120 | inserted by merge
  14 |    1430 | initial updated by merge
  14 |     140 | inserted by merge
(15 rows)

ROLLBACK;
-- as above, but blocked by BEFORE DELETE ROW trigger
BEGIN;
CREATE FUNCTION trig_fn() RETURNS trigger LANGUAGE plpgsql AS
  $$ BEGIN RETURN NULL; END; $$;
CREATE TRIGGER del_trig BEFORE DELETE ON pa_target
  FOR EACH ROW EXECUTE PROCEDURE trig_fn();
DO $$
DECLARE
  result integer;
BEGIN
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid
  WHEN MATCHED THEN
    UPDATE SET tid = tid + 1, balance = balance + delta, val = val || ' updated by merge'
  WHEN NOT MATCHED THEN
    INSERT VALUES (sid, delta, 'inserted by merge')
  WHEN NOT MATCHED BY SOURCE THEN
    UPDATE SET val = val || ' not matched by source';
GET DIAGNOSTICS result := ROW_COUNT;
RAISE NOTICE 'ROW_COUNT = %', result;
END;
$$;
NOTICE:  ROW_COUNT = 11
SELECT * FROM pa_target ORDER BY tid, val;
 tid | balance |              val              
-----+---------+-------------------------------
   1 |     100 | initial
   2 |      20 | inserted by merge
   3 |     300 | initial
   4 |      40 | inserted by merge
   6 |     550 | initial updated by merge
   6 |      60 | inserted by merge
   7 |     700 | initial
   8 |      80 | inserted by merge
   9 |     900 | initial
  10 |     100 | inserted by merge
  12 |    1210 | initial updated by merge
  12 |     120 | inserted by merge
  14 |    1430 | initial updated by merge
  14 |     140 | inserted by merge
  15 |    1500 | initial not matched by source
(15 rows)

ROLLBACK;
-- as above, but blocked by BEFORE INSERT ROW trigger
BEGIN;
CREATE FUNCTION trig_fn() RETURNS trigger LANGUAGE plpgsql AS
  $$ BEGIN RETURN NULL; END; $$;
CREATE TRIGGER ins_trig BEFORE INSERT ON pa_target
  FOR EACH ROW EXECUTE PROCEDURE trig_fn();
DO $$
DECLARE
  result integer;
BEGIN
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid
  WHEN MATCHED THEN
    UPDATE SET tid = tid + 1, balance = balance + delta, val = val || ' updated by merge'
  WHEN NOT MATCHED THEN
    INSERT VALUES (sid, delta, 'inserted by merge')
  WHEN NOT MATCHED BY SOURCE THEN
    UPDATE SET val = val || ' not matched by source';
GET DIAGNOSTICS result := ROW_COUNT;
RAISE NOTICE 'ROW_COUNT = %', result;
END;
$$;
NOTICE:  ROW_COUNT = 4
SELECT * FROM pa_target ORDER BY tid, val;
 tid | balance |              val              
-----+---------+-------------------------------
   6 |     550 | initial updated by merge
  12 |    1210 | initial updated by merge
  14 |    1430 | initial updated by merge
  15 |    1500 | initial not matched by source
(4 rows)

ROLLBACK;
-- test RLS enforcement
BEGIN;
ALTER TABLE pa_target ENABLE ROW LEVEL SECURITY;
ALTER TABLE pa_target FORCE ROW LEVEL SECURITY;
CREATE POLICY pa_target_pol ON pa_target USING (tid != 0);
MERGE INTO pa_target t
  USING pa_source s
  ON t.tid = s.sid AND t.tid IN (1,2,3,4)
  WHEN MATCHED THEN
    UPDATE SET tid = tid - 1;
ERROR:  new row violates row-level security policy for table "pa_target"
ROLLBACK;
DROP TABLE pa_source;
DROP TABLE pa_target CASCADE;
-- Sub-partitioning
CREATE TABLE pa_target (logts timestamp, tid integer, balance float, val text)
	PARTITION BY RANGE (logts);
CREATE TABLE part_m01 PARTITION OF pa_target
	FOR VALUES FROM ('2017-01-01') TO ('2017-02-01')
	PARTITION BY LIST (tid);
CREATE TABLE part_m01_odd PARTITION OF part_m01
	FOR VALUES IN (1,3,5,7,9) WITH (autovacuum_enabled=off);
CREATE TABLE part_m01_even PARTITION OF part_m01
	FOR VALUES IN (2,4,6,8) WITH (autovacuum_enabled=off);
CREATE TABLE part_m02 PARTITION OF pa_target
	FOR VALUES FROM ('2017-02-01') TO ('2017-03-01')
	PARTITION BY LIST (tid);
CREATE TABLE part_m02_odd PARTITION OF part_m02
	FOR VALUES IN (1,3,5,7,9) WITH (autovacuum_enabled=off);
CREATE TABLE part_m02_even PARTITION OF part_m02
	FOR VALUES IN (2,4,6,8) WITH (autovacuum_enabled=off);
CREATE TABLE pa_source (sid integer, delta float)
  WITH (autovacuum_enabled=off);
-- insert many rows to the source table
INSERT INTO pa_source SELECT id, id * 10  FROM generate_series(1,14) AS id;
-- insert a few rows in the target table (odd numbered tid)
INSERT INTO pa_target SELECT '2017-01-31', id, id * 100, 'initial' FROM generate_series(1,9,3) AS id;
INSERT INTO pa_target SELECT '2017-02-28', id, id * 100, 'initial' FROM generate_series(2,9,3) AS id;
-- try simple MERGE
BEGIN;
MERGE INTO pa_target t
  USING (SELECT '2017-01-15' AS slogts, * FROM pa_source WHERE sid < 10) s
  ON t.tid = s.sid
  WHEN MATCHED THEN
    UPDATE SET balance = balance + delta, val = val || ' updated by merge'
  WHEN NOT MATCHED THEN
    INSERT VALUES (slogts::timestamp, sid, delta, 'inserted by merge')
  RETURNING merge_action(), t.*;
 merge_action |          logts           | tid | balance |           val            
--------------+--------------------------+-----+---------+--------------------------
 UPDATE       | Tue Jan 31 00:00:00 2017 |   1 |     110 | initial updated by merge
 UPDATE       | Tue Feb 28 00:00:00 2017 |   2 |     220 | initial updated by merge
 INSERT       | Sun Jan 15 00:00:00 2017 |   3 |      30 | inserted by merge
 UPDATE       | Tue Jan 31 00:00:00 2017 |   4 |     440 | initial updated by merge
 UPDATE       | Tue Feb 28 00:00:00 2017 |   5 |     550 | initial updated by merge
 INSERT       | Sun Jan 15 00:00:00 2017 |   6 |      60 | inserted by merge
 UPDATE       | Tue Jan 31 00:00:00 2017 |   7 |     770 | initial updated by merge
 UPDATE       | Tue Feb 28 00:00:00 2017 |   8 |     880 | initial updated by merge
 INSERT       | Sun Jan 15 00:00:00 2017 |   9 |      90 | inserted by merge
(9 rows)

SELECT * FROM pa_target ORDER BY tid;
          logts           | tid | balance |           val            
--------------------------+-----+---------+--------------------------
 Tue Jan 31 00:00:00 2017 |   1 |     110 | initial updated by merge
 Tue Feb 28 00:00:00 2017 |   2 |     220 | initial updated by merge
 Sun Jan 15 00:00:00 2017 |   3 |      30 | inserted by merge
 Tue Jan 31 00:00:00 2017 |   4 |     440 | initial updated by merge
 Tue Feb 28 00:00:00 2017 |   5 |     550 | initial updated by merge
 Sun Jan 15 00:00:00 2017 |   6 |      60 | inserted by merge
 Tue Jan 31 00:00:00 2017 |   7 |     770 | initial updated by merge
 Tue Feb 28 00:00:00 2017 |   8 |     880 | initial updated by merge
 Sun Jan 15 00:00:00 2017 |   9 |      90 | inserted by merge
(9 rows)

ROLLBACK;
DROP TABLE pa_source;
DROP TABLE pa_target CASCADE;
-- Partitioned table with primary key
CREATE TABLE pa_target (tid integer PRIMARY KEY) PARTITION BY LIST (tid);
CREATE TABLE pa_targetp PARTITION OF pa_target DEFAULT;
CREATE TABLE pa_source (sid integer);
INSERT INTO pa_source VALUES (1), (2);
EXPLAIN (VERBOSE, COSTS OFF)
MERGE INTO pa_target t USING pa_source s ON t.tid = s.sid
  WHEN NOT MATCHED THEN INSERT VALUES (s.sid);
                         QUERY PLAN                          
-------------------------------------------------------------
 Merge on public.pa_target t
   Merge on public.pa_targetp t_1
   ->  Hash Left Join
         Output: s.sid, s.ctid, t_1.tableoid, t_1.ctid
         Inner Unique: true
         Hash Cond: (s.sid = t_1.tid)
         ->  Seq Scan on public.pa_source s
               Output: s.sid, s.ctid
         ->  Hash
               Output: t_1.tid, t_1.tableoid, t_1.ctid
               ->  Seq Scan on public.pa_targetp t_1
                     Output: t_1.tid, t_1.tableoid, t_1.ctid
(12 rows)

MERGE INTO pa_target t USING pa_source s ON t.tid = s.sid
  WHEN NOT MATCHED THEN INSERT VALUES (s.sid);
TABLE pa_target;
 tid 
-----
   1
   2
(2 rows)

-- Partition-less partitioned table
-- (the bug we are checking for appeared only if table had partitions before)
DROP TABLE pa_targetp;
EXPLAIN (VERBOSE, COSTS OFF)
MERGE INTO pa_target t USING pa_source s ON t.tid = s.sid
  WHEN NOT MATCHED THEN INSERT VALUES (s.sid);
                 QUERY PLAN                 
--------------------------------------------
 Merge on public.pa_target t
   ->  Hash Left Join
         Output: s.sid, s.ctid, t.ctid
         Inner Unique: true
         Hash Cond: (s.sid = t.tid)
         ->  Seq Scan on public.pa_source s
               Output: s.sid, s.ctid
         ->  Hash
               Output: t.tid, t.ctid
               ->  Result
                     Output: t.tid, t.ctid
                     One-Time Filter: false
(12 rows)

MERGE INTO pa_target t USING pa_source s ON t.tid = s.sid
  WHEN NOT MATCHED THEN INSERT VALUES (s.sid);
ERROR:  no partition of relation "pa_target" found for row
DETAIL:  Partition key of the failing row contains (tid) = (1).
DROP TABLE pa_source;
DROP TABLE pa_target CASCADE;
-- some complex joins on the source side
CREATE TABLE cj_target (tid integer, balance float, val text)
  WITH (autovacuum_enabled=off);
CREATE TABLE cj_source1 (sid1 integer, scat integer, delta integer)
  WITH (autovacuum_enabled=off);
CREATE TABLE cj_source2 (sid2 integer, sval text)
  WITH (autovacuum_enabled=off);
INSERT INTO cj_source1 VALUES (1, 10, 100);
INSERT INTO cj_source1 VALUES (1, 20, 200);
INSERT INTO cj_source1 VALUES (2, 20, 300);
INSERT INTO cj_source1 VALUES (3, 10, 400);
INSERT INTO cj_source2 VALUES (1, 'initial source2');
INSERT INTO cj_source2 VALUES (2, 'initial source2');
INSERT INTO cj_source2 VALUES (3, 'initial source2');
-- source relation is an unaliased join
MERGE INTO cj_target t
USING cj_source1 s1
	INNER JOIN cj_source2 s2 ON sid1 = sid2
ON t.tid = sid1
WHEN NOT MATCHED THEN
	INSERT VALUES (sid1, delta, sval);
-- try accessing columns from either side of the source join
MERGE INTO cj_target t
USING cj_source2 s2
	INNER JOIN cj_source1 s1 ON sid1 = sid2 AND scat = 20
ON t.tid = sid1
WHEN NOT MATCHED THEN
	INSERT VALUES (sid2, delta, sval)
WHEN MATCHED THEN
	DELETE;
-- some simple expressions in INSERT targetlist
MERGE INTO cj_target t
USING cj_source2 s2
	INNER JOIN cj_source1 s1 ON sid1 = sid2
ON t.tid = sid1
WHEN NOT MATCHED THEN
	INSERT VALUES (sid2, delta + scat, sval)
WHEN MATCHED THEN
	UPDATE SET val = val || ' updated by merge';
MERGE INTO cj_target t
USING cj_source2 s2
	INNER JOIN cj_source1 s1 ON sid1 = sid2 AND scat = 20
ON t.tid = sid1
WHEN MATCHED THEN
	UPDATE SET val = val || ' ' || delta::text;
SELECT * FROM cj_target;
 tid | balance |               val                
-----+---------+----------------------------------
   3 |     400 | initial source2 updated by merge
   1 |     220 | initial source2 200
   1 |     110 | initial source2 200
   2 |     320 | initial source2 300
(4 rows)

-- try it with an outer join and PlaceHolderVar
MERGE INTO cj_target t
USING (SELECT *, 'join input'::text AS phv FROM cj_source1) fj
	FULL JOIN cj_source2 fj2 ON fj.scat = fj2.sid2 * 10
ON t.tid = fj.scat
WHEN NOT MATCHED THEN
	INSERT (tid, balance, val) VALUES (fj.scat, fj.delta, fj.phv);
SELECT * FROM cj_target;
 tid | balance |               val                
-----+---------+----------------------------------
   3 |     400 | initial source2 updated by merge
   1 |     220 | initial source2 200
   1 |     110 | initial source2 200
   2 |     320 | initial source2 300
  10 |     100 | join input
  10 |     400 | join input
  20 |     200 | join input
  20 |     300 | join input
     |         | 
(9 rows)

ALTER TABLE cj_source1 RENAME COLUMN sid1 TO sid;
ALTER TABLE cj_source2 RENAME COLUMN sid2 TO sid;
TRUNCATE cj_target;
MERGE INTO cj_target t
USING cj_source1 s1
	INNER JOIN cj_source2 s2 ON s1.sid = s2.sid
ON t.tid = s1.sid
WHEN NOT MATCHED THEN
	INSERT VALUES (s2.sid, delta, sval);
DROP TABLE cj_source2, cj_source1, cj_target;
-- Function scans
CREATE TABLE fs_target (a int, b int, c text)
  WITH (autovacuum_enabled=off);
MERGE INTO fs_target t
USING generate_series(1,100,1) AS id
ON t.a = id
WHEN MATCHED THEN
	UPDATE SET b = b + id
WHEN NOT MATCHED THEN
	INSERT VALUES (id, -1);
MERGE INTO fs_target t
USING generate_series(1,100,2) AS id
ON t.a = id
WHEN MATCHED THEN
	UPDATE SET b = b + id, c = 'updated '|| id.*::text
WHEN NOT MATCHED THEN
	INSERT VALUES (id, -1, 'inserted ' || id.*::text);
SELECT count(*) FROM fs_target;
 count 
-------
   100
(1 row)

DROP TABLE fs_target;
-- SERIALIZABLE test
-- handled in isolation tests
-- Inheritance-based partitioning
CREATE TABLE measurement (
    city_id         int not null,
    logdate         date not null,
    peaktemp        int,
    unitsales       int
) WITH (autovacuum_enabled=off);
CREATE TABLE measurement_y2006m02 (
    CHECK ( logdate >= DATE '2006-02-01' AND logdate < DATE '2006-03-01' )
) INHERITS (measurement) WITH (autovacuum_enabled=off);
CREATE TABLE measurement_y2006m03 (
    CHECK ( logdate >= DATE '2006-03-01' AND logdate < DATE '2006-04-01' )
) INHERITS (measurement) WITH (autovacuum_enabled=off);
CREATE TABLE measurement_y2007m01 (
    filler          text,
    peaktemp        int,
    logdate         date not null,
    city_id         int not null,
    unitsales       int
    CHECK ( logdate >= DATE '2007-01-01' AND logdate < DATE '2007-02-01')
) WITH (autovacuum_enabled=off);
ALTER TABLE measurement_y2007m01 DROP COLUMN filler;
ALTER TABLE measurement_y2007m01 INHERIT measurement;
INSERT INTO measurement VALUES (0, '2005-07-21', 5, 15);
CREATE OR REPLACE FUNCTION measurement_insert_trigger()
RETURNS TRIGGER AS $$
BEGIN
    IF ( NEW.logdate >= DATE '2006-02-01' AND
         NEW.logdate < DATE '2006-03-01' ) THEN
        INSERT INTO measurement_y2006m02 VALUES (NEW.*);
    ELSIF ( NEW.logdate >= DATE '2006-03-01' AND
            NEW.logdate < DATE '2006-04-01' ) THEN
        INSERT INTO measurement_y2006m03 VALUES (NEW.*);
    ELSIF ( NEW.logdate >= DATE '2007-01-01' AND
            NEW.logdate < DATE '2007-02-01' ) THEN
        INSERT INTO measurement_y2007m01 (city_id, logdate, peaktemp, unitsales)
            VALUES (NEW.*);
    ELSE
        RAISE EXCEPTION 'Date out of range.  Fix the measurement_insert_trigger() function!';
    END IF;
    RETURN NULL;
END;
$$ LANGUAGE plpgsql ;
CREATE TRIGGER insert_measurement_trigger
    BEFORE INSERT ON measurement
    FOR EACH ROW EXECUTE PROCEDURE measurement_insert_trigger();
INSERT INTO measurement VALUES (1, '2006-02-10', 35, 10);
INSERT INTO measurement VALUES (1, '2006-02-16', 45, 20);
INSERT INTO measurement VALUES (1, '2006-03-17', 25, 10);
INSERT INTO measurement VALUES (1, '2006-03-27', 15, 40);
INSERT INTO measurement VALUES (1, '2007-01-15', 10, 10);
INSERT INTO measurement VALUES (1, '2007-01-17', 10, 10);
SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate;
       tableoid       | city_id |  logdate   | peaktemp | unitsales 
----------------------+---------+------------+----------+-----------
 measurement          |       0 | 07-21-2005 |        5 |        15
 measurement_y2006m02 |       1 | 02-10-2006 |       35 |        10
 measurement_y2006m02 |       1 | 02-16-2006 |       45 |        20
 measurement_y2006m03 |       1 | 03-17-2006 |       25 |        10
 measurement_y2006m03 |       1 | 03-27-2006 |       15 |        40
 measurement_y2007m01 |       1 | 01-15-2007 |       10 |        10
 measurement_y2007m01 |       1 | 01-17-2007 |       10 |        10
(7 rows)

CREATE TABLE new_measurement (LIKE measurement) WITH (autovacuum_enabled=off);
INSERT INTO new_measurement VALUES (0, '2005-07-21', 25, 20);
INSERT INTO new_measurement VALUES (1, '2006-03-01', 20, 10);
INSERT INTO new_measurement VALUES (1, '2006-02-16', 50, 10);
INSERT INTO new_measurement VALUES (2, '2006-02-10', 20, 20);
INSERT INTO new_measurement VALUES (1, '2006-03-27', NULL, NULL);
INSERT INTO new_measurement VALUES (1, '2007-01-17', NULL, NULL);
INSERT INTO new_measurement VALUES (1, '2007-01-15', 5, NULL);
INSERT INTO new_measurement VALUES (1, '2007-01-16', 10, 10);
BEGIN;
MERGE INTO ONLY measurement m
 USING new_measurement nm ON
      (m.city_id = nm.city_id and m.logdate=nm.logdate)
WHEN MATCHED AND nm.peaktemp IS NULL THEN DELETE
WHEN MATCHED THEN UPDATE
     SET peaktemp = greatest(m.peaktemp, nm.peaktemp),
        unitsales = m.unitsales + coalesce(nm.unitsales, 0)
WHEN NOT MATCHED THEN INSERT
     (city_id, logdate, peaktemp, unitsales)
   VALUES (city_id, logdate, peaktemp, unitsales);
SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate, peaktemp;
       tableoid       | city_id |  logdate   | peaktemp | unitsales 
----------------------+---------+------------+----------+-----------
 measurement          |       0 | 07-21-2005 |       25 |        35
 measurement_y2006m02 |       1 | 02-10-2006 |       35 |        10
 measurement_y2006m02 |       1 | 02-16-2006 |       45 |        20
 measurement_y2006m02 |       1 | 02-16-2006 |       50 |        10
 measurement_y2006m03 |       1 | 03-01-2006 |       20 |        10
 measurement_y2006m03 |       1 | 03-17-2006 |       25 |        10
 measurement_y2006m03 |       1 | 03-27-2006 |       15 |        40
 measurement_y2006m03 |       1 | 03-27-2006 |          |          
 measurement_y2007m01 |       1 | 01-15-2007 |        5 |          
 measurement_y2007m01 |       1 | 01-15-2007 |       10 |        10
 measurement_y2007m01 |       1 | 01-16-2007 |       10 |        10
 measurement_y2007m01 |       1 | 01-17-2007 |       10 |        10
 measurement_y2007m01 |       1 | 01-17-2007 |          |          
 measurement_y2006m02 |       2 | 02-10-2006 |       20 |        20
(14 rows)

ROLLBACK;
MERGE into measurement m
 USING new_measurement nm ON
      (m.city_id = nm.city_id and m.logdate=nm.logdate)
WHEN MATCHED AND nm.peaktemp IS NULL THEN DELETE
WHEN MATCHED THEN UPDATE
     SET peaktemp = greatest(m.peaktemp, nm.peaktemp),
        unitsales = m.unitsales + coalesce(nm.unitsales, 0)
WHEN NOT MATCHED THEN INSERT
     (city_id, logdate, peaktemp, unitsales)
   VALUES (city_id, logdate, peaktemp, unitsales);
SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate;
       tableoid       | city_id |  logdate   | peaktemp | unitsales 
----------------------+---------+------------+----------+-----------
 measurement          |       0 | 07-21-2005 |       25 |        35
 measurement_y2006m02 |       1 | 02-10-2006 |       35 |        10
 measurement_y2006m02 |       1 | 02-16-2006 |       50 |        30
 measurement_y2006m03 |       1 | 03-01-2006 |       20 |        10
 measurement_y2006m03 |       1 | 03-17-2006 |       25 |        10
 measurement_y2007m01 |       1 | 01-15-2007 |       10 |        10
 measurement_y2007m01 |       1 | 01-16-2007 |       10 |        10
 measurement_y2006m02 |       2 | 02-10-2006 |       20 |        20
(8 rows)

BEGIN;
MERGE INTO new_measurement nm
 USING ONLY measurement m ON
      (nm.city_id = m.city_id and nm.logdate=m.logdate)
WHEN MATCHED THEN DELETE;
SELECT * FROM new_measurement ORDER BY city_id, logdate;
 city_id |  logdate   | peaktemp | unitsales 
---------+------------+----------+-----------
       1 | 02-16-2006 |       50 |        10
       1 | 03-01-2006 |       20 |        10
       1 | 03-27-2006 |          |          
       1 | 01-15-2007 |        5 |          
       1 | 01-16-2007 |       10 |        10
       1 | 01-17-2007 |          |          
       2 | 02-10-2006 |       20 |        20
(7 rows)

ROLLBACK;
MERGE INTO new_measurement nm
 USING measurement m ON
      (nm.city_id = m.city_id and nm.logdate=m.logdate)
WHEN MATCHED THEN DELETE;
SELECT * FROM new_measurement ORDER BY city_id, logdate;
 city_id |  logdate   | peaktemp | unitsales 
---------+------------+----------+-----------
       1 | 03-27-2006 |          |          
       1 | 01-17-2007 |          |          
(2 rows)

DROP TABLE measurement, new_measurement CASCADE;
NOTICE:  drop cascades to 3 other objects
DETAIL:  drop cascades to table measurement_y2006m02
drop cascades to table measurement_y2006m03
drop cascades to table measurement_y2007m01
DROP FUNCTION measurement_insert_trigger();
-- prepare
RESET SESSION AUTHORIZATION;
DROP TABLE target, target2;
DROP TABLE source, source2;
DROP FUNCTION merge_trigfunc();
DROP USER regress_merge_privs;
DROP USER regress_merge_no_privs;
DROP USER regress_merge_none;