On 30th of June, Alvaro Herrera committed patch: Enable CHECK constraints to be declared NOT VALID This means that they can initially be added to a large existing table without checking its initial contents, but new tuples must comply to them; a separate pass ...

there are this situations where you need (or you think you need) to get multiple values from sequence. for example - you're importing lots of data: some objects, some objects which relate to base objects, and so on. of course you can ...