Re: creating CHECK constraints as NOT VALID

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>

To: Alvaro Herrera <alvherre@alvh.no-ip.org>

Cc: Pg Hackers <pgsql-hackers@postgresql.org>

Date: 2011-05-31T16:36:26Z

Lists: pgsql-hackers

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Fix pg_get_constraintdef to cope with NOT VALID constraints
- 048417511aef 9.1.0 cited

On Tue, May 31, 2011 at 12:04 PM, Alvaro Herrera
<alvherre@alvh.no-ip.org> wrote:
> This patch allows you to initially declare a CHECK constraint as NOT
> VALID, similar to what we already allow for foreign keys.  That is, you
> create the constraint without scanning the table and after it is
> committed, it is enforced for new rows; later, all rows are checked by
> running ALTER TABLE VALIDATE CONSTRAINT, which doesn't need
> AccessExclusive thus allowing for better concurrency.
>
> The trickiest bit here was realizing that unlike FKs, check constraints
> do inherit, and so needed special treatment for recursion.  Other than
> that I think this was pretty straightforward.
>
> I intend to attempt to apply this to NOT NULL constraints as well, once
> the patch to add them to pg_constraint is in.

Seems like a logical extension of what we have now.

-- 
Robert Haas
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