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Re: default values in inheritance hierarchies

From: Miroslav Šimulčík <simulcik(dot)miro(at)gmail(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: default values in inheritance hierarchies
Date: 2012-02-27 21:50:03
Message-ID: CAHRNM6_pAGoXPh_XV0B0GW0uJd8BMkBEJ+sS4HG3_tmSjLX1xQ@mail.gmail.com (view raw or flat)
Thread:
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Sorry, I have accidentaly sent incomplet mail.

Here is the rest:

The following sequence of commands will end up with error, because of
duplicate ID in table a2:

    insert into a2(data2, data) values(456, 'jkl');
    insert into a2(data2, data) values(789, 'mno');

Is there any way how to force UPDATE to use default value of ID column from
table a2 when updating rows in this table, without using triggers?

Thank you

Best regards
Miroslav Simulcik

2012/2/27 Miroslav Šimulčík <simulcik(dot)miro(at)gmail(dot)com>

> Hi,
>
> I have two tables defined for example like this:
>
>     create table a1 (id serial primary key, data text);
>     create table a2 (id serial primary key, data2 integer) inherits (a1);
>
> The point is, that I want to have two tables with inheritance relation
> between them, but each with its own id column (overriden in child table).
>
> Then I execute this sequence of commands:
>
>     insert into a1(data) values('abc');
>     insert into a2(data2, data) values(123, 'def');
>     update a1 set id = default, data = 'ghi';
>
> I need new IDs on each update, because I store old rows in another table
> to keep history of changes. Problem is that update uses values from
> sequence belonging to table a1 when updating rows in table a2.
>
> So the content of tables after operations is:
>
> select * from only a1;
>  id | data
> ----+------
>   2 | ghi
>
> select * from a2;
>  id | data | data2
> ----+------+-------
>   3 | ghi  |   123
>
> The following sequence of commands ends up wit
>

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Next:From: Alvaro HerreraDate: 2012-02-27 22:21:04
Subject: Re: Avoid FK validations for no-rewrite ALTER TABLE ALTER TYPE
Previous:From: Miroslav ŠimulčíkDate: 2012-02-27 21:41:59
Subject: default values in inheritance hierarchies

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