Обсуждение: Deferrerable Check constraints

Hi All,

Need a Help. Can a check constraint be deferred until the end of a
transaction  ?
In other words, if i have a constraint like this:

CREATE TABLE test
(
  id serial NOT NULL,
  qt1 integer NOT NULL DEFAULT 0,
  qt2 integer NOT NULL DEFAULT 0,
  CONSTRAINT check_qt CHECK (qt1 <= qt2)
)

There are some manner that allow qt1 to be greater than qt2 on a
intermediate state of the transaction ?

Thanks in Advance

--
Luiz K. Matsumura
Plan IT Tecnologia Informática Ltda.

"Luiz K. Matsumura" <luiz@planit.com.br> writes:
> Need a Help. Can a check constraint be deferred until the end of a
> transaction  ?

Nope, sorry.

If you're desperate to have such functionality you could check the
condition in a "constraint trigger".
http://www.postgresql.org/docs/8.3/static/sql-createconstraint.html

            regards, tom lane

--- On Mon, 11/24/08, Luiz K. Matsumura <luiz@planit.com.br> wrote:

> Hi All,
>
> Need a Help. Can a check constraint be deferred until the
> end of a transaction  ?
> In other words, if i have a constraint like this:
>
> CREATE TABLE test
> (
>  id serial NOT NULL,
>  qt1 integer NOT NULL DEFAULT 0,
>  qt2 integer NOT NULL DEFAULT 0,
>  CONSTRAINT check_qt CHECK (qt1 <= qt2)
> )
>
> There are some manner that allow qt1 to be greater than qt2
> on a intermediate state of the transaction ?

Is this something that could be handled with update and/or insert triggers?

Bruce

Bruce Hyatt wrote:
> Is this something that could be handled with update and/or insert triggers?
>
I think that no, because there are no way to determine what
insert/update is the last of a transaction inside a trigger.

--
Luiz K. Matsumura
Plan IT Tecnologia Informática Ltda.