In article <1343d11c-6f58-4653-8ea8-837c01e61...@unicell.co.il>,
Herouth Maoz <hero...@unicell.co.il> writes:
> On 22/08/2011, at 01:19, Harald Fuchs wrote:
>> In article <caf36091-203e-4c10-aa53-7d9087114...@unicell.co.il>,
>> Herouth Maoz <hero...@unicell.co.il> writes:
>>
>>> Hi,
>>> I'm designing a new database. One of the table contains allowed IP ranges
>>> for a customer (Fields: customer_id, from_ip, to_ip) which is intended to
>>> check - if an incoming connection's originating IP number falls within the
>>> range, it is identified as a particular customer.
>>
>>> Naturally, I'd like to have constraints on the table that prevent entering
>>> of ip ranges that overlap. Is there a way to do that with exclusion
>>> constraints? Or do I have to define a new type for this?
>>
>> This "new type" already exists: ip4r, which can be found in pgfoundry.
>> With it you can do
>>
>> CREATE TABLE mytbl (
>> iprange ip4r NOT NULL,
>> ...,
>> CONSTRAINT range_check CHECK ((NOT overlap(iprange)))
>> );
> Thank you.
> I assume you can't use a CHECK constraint for between-rows constraints.
> Wouldn't this be
> CONSTRAINT EXCLUDE ( iprange WITH && )
> ?
You're right. In the old PostgreSQL version I had to use I defined a
helper function
CREATE FUNCTION overlap(ip4r) RETURNS boolean
LANGUAGE sql
AS $_$
SELECT count(*) > 0
FROM mytbl
WHERE iprange != $1 AND iprange && $1
$_$;
for the CHECK CONSTRAINT, but in more recent PostgreSQL versions you can
just say
EXCLUDE (iprange WITH &&)
(without CONSTRAINT).
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