or download this
CREATE FUNCTION skip_update() RETURNS trigger AS $$
BEGIN
...
INSERT INTO Dummy_Test (Timestamp,Foo,Bar) VALUES ('2020-01-02 12:34',
+'Hello','World') ON CONFLICT ON CONSTRAINT Dummy_Test_pkey DO UPDATE
+SET Foo=EXCLUDED.Foo, Bar=EXCLUDED.Bar;
INSERT INTO Dummy_Test (Timestamp,Foo,Bar) VALUES ('2020-01-02 12:34',
+'Hello','World') ON CONFLICT ON CONSTRAINT Dummy_Test_pkey DO UPDATE
+SET Foo=EXCLUDED.Foo, Bar=EXCLUDED.Bar;
INSERT INTO Dummy_Test (Timestamp,Foo,Bar) VALUES ('2020-01-02 12:34',
+'Hello','abcde') ON CONFLICT ON CONSTRAINT Dummy_Test_pkey DO UPDATE
+SET Foo=EXCLUDED.Foo, Bar=EXCLUDED.Bar;