On Wed, Jun 4, 2025 at 9:37 AM Peter Eisentraut <[email protected]> wrote:
> On 03.05.25 17:42, Robert Treat wrote:
> > I actually think this mix of VALID / ENFORCED is a little convoluted
> > for end users, but I don't think the system catalog documentation is
> > the best place to work that out, and I see we've also not added this
> > type of extra information to other columns in the table that have
> > similar restrictions, so I think removing it is the right move.
> >
> > As such, attached patch removes the above, and attempts some clean up
> > of the documentation in ALTER TABLE to better clarify the behavior
> > around valid/not valid, enforced/not enforced, and how it affects
> > different constraints, with some additional literal tag formatting
> > changes.
>
> I committed the catalog.sgml change. I don't agree with some of the
> other changes, such as changing foreign key to >FOREIGN KEY< etc. It
> was hard to tell if there were any other changes in there that could be
> considered separately from that.
>
I think some of those changes are worth a second stab, so here is an
updated patch which removes the ancillary tagging and corresponding
line wrappings and focuses just on the wording/grammer improvements;
hopefully it will be easier to make sense of.
Robert Treat
https://xzilla.net
diff --git a/doc/src/sgml/ref/alter_table.sgml
b/doc/src/sgml/ref/alter_table.sgml
index d63f3a621ac..dc02d6d8b58 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -461,7 +461,7 @@ WITH ( MODULUS <replaceable
class="parameter">numeric_literal</replaceable>, REM
This form adds a new constraint to a table using the same constraint
syntax as <link linkend="sql-createtable"><command>CREATE
TABLE</command></link>, plus the option <literal>NOT
VALID</literal>, which is currently only allowed for foreign key,
- <literal>CHECK</literal> constraints and not-null constraints.
+ <literal>CHECK</literal>, and not-null constraints.
</para>
<para>
@@ -469,7 +469,7 @@ WITH ( MODULUS <replaceable
class="parameter">numeric_literal</replaceable>, REM
existing rows in the table satisfy the new constraint. But if
the <literal>NOT VALID</literal> option is used, this
potentially-lengthy scan is skipped. The constraint will still be
- enforced against subsequent inserts or updates (that is, they'll fail
+ applied against subsequent inserts or updates (that is, they'll fail
unless there is a matching row in the referenced table, in the case
of foreign keys, or they'll fail unless the new row matches the
specified check condition). But the
@@ -591,7 +591,7 @@ WITH ( MODULUS <replaceable
class="parameter">numeric_literal</replaceable>, REM
This form validates a foreign key, check, or not-null constraint that was
previously created as <literal>NOT VALID</literal>, by scanning the
table to ensure there are no rows for which the constraint is not
- satisfied. If the constraint is not enforced, an error is thrown.
+ satisfied. If the constraint was created as <literal>NOT
ENFORCED</literal>, an error is thrown.
Nothing happens if the constraint is already marked valid.
(See <xref linkend="sql-altertable-notes"/> below for an explanation
of the usefulness of this command.)
@@ -1466,11 +1466,11 @@ WITH ( MODULUS <replaceable
class="parameter">numeric_literal</replaceable>, REM
</para>
<para>
- Adding an enforced <literal>CHECK</literal> or <literal>NOT NULL</literal>
+ Adding a <literal>CHECK</literal> or <literal>NOT NULL</literal>
constraint requires scanning the table to verify that existing rows meet
the
constraint, but does not require a table rewrite. If a
<literal>CHECK</literal>
- constraint is added as <literal>NOT ENFORCED</literal>, the validation will
- not be performed.
+ constraint is added as <literal>NOT ENFORCED</literal>, no verification
will
+ be performed.
</para>
<para>
@@ -1485,7 +1485,7 @@ WITH ( MODULUS <replaceable
class="parameter">numeric_literal</replaceable>, REM
</para>
<para>
- Scanning a large table to verify a new foreign key or check constraint
+ Scanning a large table to verify new foreign key, check, or not null
constraints
can take a long time, and other updates to the table are locked out
until the <command>ALTER TABLE ADD CONSTRAINT</command> command is
committed. The main purpose of the <literal>NOT VALID</literal>
