Horton

Re: not null constraints, again

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

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: jian he <jian.universality@gmail.com>
Cc: Tender Wang <tndrwang@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-09-20T12:08:28Z
Lists: pgsql-hackers 
On 2024-Sep-20, jian he wrote:

> about set_attnotnull.
> 
> we can make set_attnotnull  look less recursive.
> instead of calling find_inheritance_children,
> let's just one pass, directly call  find_all_inheritors
> overall, I think it would be more intuitive.
> 
> please check the attached refactored set_attnotnull.
> regress test passed, i only test regress.

Hmm, what do we gain from doing this change?  It's longer in number of
lines of code, and it's not clear to me that it is simpler.

> I am also beginning to wonder if ATExecSetNotNull inside can also call
> find_all_inheritors.

The point of descending levels one by one in ATExecSetNotNull is that we
can stop for any child on which a constraint already exists.  We don't
need to scan any children thereof, which saves work.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/
"Use it up, wear it out, make it do, or do without"

Commits

  1. Suppress "may be used uninitialized" warnings from older compilers.

  2. Elide not-null constraint checks on child tables during PK creation

  3. Remove unnecessary code to handle CONSTR_NOTNULL

  4. Silence compilers about extractNotNullColumn()

  5. Add pg_constraint rows for not-null constraints