Re: exclusion constraint for ranges of IP

On Tue, Aug 23, 2011 at 1:27 AM, Herouth Maoz <herouth(at)unicell(dot)co(dot)il> wrote:

> My thanks to everyone who replied.
>
> I have decided not to implement that constraint at this time. Using a
> compound type will make the system more complicated and less readable, plus
> requires installing the package which is beyond vanilla PostgreSQL.
>
> Now I have another exclusion constraint I'm thinking about in another and I
> want to verify that this will do what I mean it to do:
>
> CREATE TABLE invoice_definitions
> (
> id SERIAL PRIMARY KEY NOT NULL,
> customer_id INTEGER NOT NULL REFERENCES customers(id),
> is_default BOOLEAN NOT NULL DEFAULT FALSE,
> bill_description VARCHAR(100) NOT NULL,
> itemized_description VARCHAR(100) NOT NULL,
> EXCLUDE USING GIST ( customer_id WITH =, is_default WITH AND )
> )
> ;
>
> Basically, each customer can have several rows in this table, but only one
> per customer is allowed to have is_default = true. Is this exclude
> constraint correct?
>

You can validate this yourself with 3 insert statements into the table
declared in your email.