Re: What is the postgres version of mysql's "ON DUPLICATE KEY"

> INSERT INTO related_products (product_id,related_product_id)
> SELECT 1, 2 WHERE NOT EXISTS (SELECT 1
>                                                        FROM
> related_products
>                                                        WHERE
> product_id = 1 AND related_product_id = 2)

    Should not the SELECT be FOR UPDATE ?
    because if no insert is done, the OP wanted to UPDATE the row, so it
should not be deleted by another transaction in-between...

    Can the above query fail if another transaction inserts a row between the
SELECT and the INSERT or postgres guarantee that this won't happen ?