Bulk/batch update/upsert in PostgreSQL

Question

I\'m writing a Django-ORM enchancement that attempts to cache models and postpone model saving until the end of the transaction. It\'s all almost done, however I came across

Answer 1

it is pretty fast to populate json into recordset (postgresql 9.3+)

big_list_of_tuples = [
    (1, "123.45"),
    ...
    (100000, "678.90"),
]

connection.execute("""
    UPDATE mytable
    SET myvalue = Q.myvalue
    FROM (
        SELECT (value->>0)::integer AS id, (value->>1)::decimal AS myvalue 
        FROM json_array_elements(%s)
    ) Q
    WHERE mytable.id = Q.id
    """, 
    [json.dumps(big_list_of_tuples)]
)