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: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Tender Wang <tndrwang@gmail.com>, jian he <jian.universality@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-04-16T11:24:13Z
Lists: pgsql-hackers

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Here's another version where I do skip searching for children twice, and
rewrote the comments.

I also noticed that in child tables we were only looking for
pg_attribute.attnotnull, and not whether the constraints had been
validated or made inheritable.  This seemed a wasted opportunity, so I
refactored the code to instead examine the pg_constraint row and apply
the same checks as for the constraint on the parent (namely, that it's
valid and not NO INHERIT).  We already check for these things downstream
(alter table phase 2, during AdjustNotNullInheritance), but only after
potentially wasting more work, so it makes sense to do it here (alter
table phase 1) given that it's very easy.  I added some tests for these
things also, as those cases weren't covered.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"¿Cómo puedes confiar en algo que pagas y que no ves,
y no confiar en algo que te dan y te lo muestran?" (Germán Poo)

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