Re: how to correctly invalidate a constraint?

2017-01-13 22:44 GMT+01:00 Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>:

> Pavel Stehule wrote:
> > Hi
> >
> > I would to do import without RI check - so I disable RI triggers.
> >
> > I would to invalidate constraint on Foreign Keys and then I would to use
> > ALTER TABLE VALIDATE CONSTRAINT ...
> >
> > I didn't find how to invalidate constraint without direct update
> > pg_constraint.
> >
> > Is there some clean way?
>
> I think what you want is:
> - set the constraint as "not valid", so that the following is a valid
> operation
> - set the RI trigger not to fire, to improve performance of bulk loads
> - do the load
> - activate the trigger
> - validate the constraint
>

yes

>
> We have SQL commands for everything except the first step. Now my
> question would be: do we want to support that operation as a stand-alone
> thing so that you can construct the above from pieces, or do we want
> some higher-level command so that the above is less cumbersome? The
> main issue I see is that a single constraint involves several triggers,
> and the triggers have internally-derived, very ugly names. So in my
> mind the right way to provide this functionality is to have a command
> that operates on the RI constraint and modifies the triggers status.
>
> ALTER TABLE .. ALTER CONSTRAINT [name / ALL] DEACTIVATE
> -- sets constraint as NOT VALID, also sets triggers inactive
>
> [user bulkload occurs here]
>
> ALTER TABLE .. ALTER CONSTRAINT [name / ALL] ACTIVATE
> -- activates triggers, validates constraint
>

In this case I prefer simple low level command

ALTER TABLE .. ALTER CONSTRAINT name NOT VALID

It should to set catalog to state after new NOT VALID constraint.

Regards

Pavel

>
> --
> Álvaro Herrera https://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>