--DROP TABLE t_t ;
BEGIN;
CREATE TABLE t_t 
(part integer NOT NULL 
,t_id serial primary key
,fld text 
,CHECK (part is null ) no inherit 
);

CREATE TABLE t_1
(
 CHECK (part =1 ) no inherit 
)
inherits (t_t)
;
CREATE TABLE t_2
(
 CHECK (part = 2 ) no inherit 
)
inherits (t_t)
;
CREATE VIEW t AS select * from t_t;
ALTER TABLE t ALTER t_id SET DEFAULT nextval('t_t_t_id_seq'::regclass); -- удобства на улице

CREATE OR REPLACE FUNCTION part_insert_trigger()
RETURNS TRIGGER AS $body$
BEGIN
	IF (NEW.part= 1) THEN
		INSERT INTO t_1 VALUES (NEW.*);
	ELSIF (NEW.part = 2) THEN
		INSERT INTO t_2 VALUES (NEW.*);
	ELSE
		--RAISE EXCEPTION 'partition key is out of range.  Fix the trigger function';
		INSERT INTO t_t VALUES (NEW.*);
	END IF;
	RETURN NEW; -- RETURN NEW in this case, typically you'd return NULL from this trigger, but for views we return NEW
END;
$body$
LANGUAGE plpgsql;

CREATE TRIGGER ins
INSTEAD OF INSERT ON t
FOR EACH ROW EXECUTE PROCEDURE part_insert_trigger(); -- create "INSTEAD OF" trigger
--tests

	--INSERT INTO t (part,t_id,fld) values (0,default,'0-error-chk');
	INSERT INTO t (part,t_id,fld) values (1,default,'1-chk');
	SELECT tableoid::regclass,* FROM t_t;
	INSERT INTO t (part,t_id,fld) values (2,default,'2-chk');
	SELECT tableoid::regclass,* FROM t_t;
	--UPDATE t SET part = 1 + (part %2);
---UPDATE---
CREATE OR REPLACE FUNCTION part_update_trigger()
RETURNS TRIGGER AS $body$
BEGIN
	
	IF (NEW.part= OLD.part) THEN
		UPDATE t_t SET	part	=NEW.part
				,t_id	=NEW.t_id
				,fld = 	NEW.fld
		WHERE 	
			t_t.part	=NEW.part
			AND t_t.t_id	=NEW.t_id;
	ELSE
		DELETE FROM t_t WHERE t_id = OLD.t_id;
		INSERT INTO t VALUES (NEW.*);
	END IF;
	RETURN NEW; -- RETURN NEW in this case, typically you'd return NULL from this trigger, but for views we return NEW
END;
$body$
LANGUAGE plpgsql;

CREATE TRIGGER upd
INSTEAD OF UPDATE ON t
FOR EACH ROW EXECUTE PROCEDURE part_update_trigger(); -- create "INSTEAD OF" trigger
/*
-- check moving end not moving cases 
	UPDATE t SET part = 1 + (part %2);
	SELECT tableoid::regclass,* FROM t_t;
	UPDATE t SET fld = fld||' check ';
	SELECT tableoid::regclass,* FROM t_t;
--*/
-- finally tests^
--
	UPDATE t SET fld = fld ||' recheck 0'
	RETURNING t.*;
--
	UPDATE t SET	part = 1 + (part %2)
			, fld = fld ||' recheck1'
	RETURNING t.*;
--
	UPDATE t SET	part = 1 + (part %2)
		, fld = fld ||' recheck2'
	RETURNING t.*;
	
ROLLBACK ;