In article <1343D11C-6F58-4653-8EA8-837C01E6184F@unicell.co.il>,
Herouth Maoz <herouth@unicell.co.il> writes:
> On 22/08/2011, at 01:19, Harald Fuchs wrote:
>> In article <CAF36091-203E-4C10-AA53-7D9087114D35@unicell.co.il>,
>> Herouth Maoz <herouth@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,
itis 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
wayto 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).
