Re: not null constraints, again

On Fri, Oct 4, 2024 at 9:11 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
>
> Here's v8 of this patch.

in AdjustNotNullInheritance
if (count > 0)
{
conform->coninhcount += count;
changed = true;
}
if (is_local)
{
conform->conislocal = true;
changed = true;
}

change to

if (count > 0)
{
conform->coninhcount += count;
changed = true;
}
if (is_local && !conform->conislocal)
{
conform->conislocal = true;
changed = true;
}

then we can save some cycles.

-------------------<<>>>>------------
MergeConstraintsIntoExisting
/*
* If the CHECK child constraint is "no inherit" then cannot
* merge.
*/
if (child_con->connoinherit)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("constraint \"%s\" conflicts with
non-inherited constraint on child table \"%s\"",
NameStr(child_con->conname),
RelationGetRelationName(child_rel))));
the comments apply to not-null constraint aslo, so the comments need
to be refactored.

-------------------<<>>>>------------
in ATExecSetNotNull
if (recursing)
{
conForm->coninhcount++;
changed = true;
}

grep "coninhcount++", I found out pattern:
constrForm->coninhcount++;
if (constrForm->coninhcount < 0)
ereport(ERROR,
errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("too many inheritance parents"));

here, maybe we can change to
if (recursing)
{
// conForm->coninhcount++;
if (pg_add_s16_overflow(conForm->coninhcount,1,
&conForm->coninhcount))
ereport(ERROR,
errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("too many inheritance parents"));
changed = true;
}
-------------------<<>>>>------------
base on your reply at [1]

By contrast, a <literal>NOT NULL</literal> constraint that was created
as <literal>NO INHERIT</literal> will be changed to a normal inheriting
one during attach.

these text should removed from section:
<<ATTACH PARTITION partition_name { FOR VALUES partition_bound_spec |
DEFAULT }>>
since currently v8, partition_name not-null no inherit constraint
cannot merge with the parent.

[1] https://www.postgresql.org/message-id/202410021219.bvjmxzdspif2%40alvherre.pgsql