Re: integrity and inherit

Bo Lorentsen wrote:
>I hope someone will be so kind to take the time to explain to me what I
>have been doing wrong in this example.
...
>CREATE TABLE base (
> id INTEGER PRIMARY KEY,
> name TEXT
>);
>
>CREATE TABLE derived (
> value INTEGER
>) INHERITS( base );
>
>CREATE TABLE test_ref (
> ref_id INTEGER REFERENCES base,
> name TEXT
>);
...
>INSERT INTO base (id, name) VALUES( 1, 'mother' );
>INSERT INTO derived (id, name, value) VALUES( 2, 'child', 42 );
>
>INSERT INTO test_ref (ref_id, name) VALUES( 1, 'mother' );
>
>All this works, but this one dont :
>
>INSERT INTO test_ref (ref_id, name) VALUES( 2, 'child' );
>
>Here it says :
>
>ERROR: <unnamed> referential integrity violation - key referenced from
>test_ref not found in base

Referential integrity doesn't support references to inheritance hierarchies.
You will have to redesign your database.

For example, have a trigger on each table in the hierarchy to update a
table of keys and use RI on that; it would also help you to maintain
primary keys -- you probably think that table derived inherits the
primary key constraint from base, but it doesn't. That is another problem
with the current implementation of inheritance. :-(

--
Oliver Elphick Oliver(dot)Elphick(at)lfix(dot)co(dot)uk
Isle of Wight http://www.lfix.co.uk/oliver
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