Re: not null constraints, again

Alvaro Herrera <alvherre@alvh.no-ip.org> 于2024年8月31日周六 11:59写道：

> Hello
>
> Here I present another attempt at making not-null constraints be
> catalogued.  This is largely based on the code reverted at 9ce04b50e120,
> except that we now have a not-null constraint automatically created for
> every column of a primary key, and such constraint cannot be removed
> while the PK exists.  Thanks to this, a lot of rather ugly code is gone,
> both in pg_dump and in backend -- in particular the handling of NO
> INHERIT, which was needed for pg_dump.
>
> Noteworthy psql difference: because there are now even more not-null
> constraints than before, the \d+ display would be far too noisy if we
> just let it grow.  So here I've made it omit any constraints that
> underlie the primary key.  This should be OK since you can't do much
> with those constraints while the PK is still there.  If you drop the PK,
> the next \d+ will show those constraints.
>
> One thing that regretfully I haven't yet had time for, is paring down
> the original test code: a lot of it is verifying the old semantics,
> particularly for NO INHERIT constraints, which had grown ugly special
> cases.  It now mostly raises errors; or the tests are simply redundant.
> I'm going to remove that stuff as soon as I'm back on my normal work
> timezone.
>
> sepgsql is untested.
>
> I'm adding this to the September commitfest.


Thanks for working on this again.

 AT_PASS_OLD_COL_ATTRS, I didn't see any other code that used it. I don't
think it's necessary.

I will take the time to look over the attached patch.

-- 
Tender Wang