ON CONFLICT (name, age)
DO UPDATE SET
    occupation = 'teacher'
ELSE ON CONFLICT(all others) DO NOTHING;

CREATE UNIQUE INDEX index1 ON contact USING btree (name, age);
CREATE UNIQUE INDEX index2 ON contact USING btree (name, address) WHERE (address IS NOT NULL);
CREATE UNIQUE INDEX index3 ...
CREATE UNIQUE INDEX index4 ...

INSERT INTO contact
    (name,
    age,
    address,
    occupation)
VALUES
    ('John',
    25,
    '1 main st',
    'doctor')
ON CONFLICT (name, age)
DO UPDATE SET
    occupation = 'teacher';