Recast "ONLY" column CHECK constraints as NO INHERIT

The original syntax wasn't universally loved, and it didn't allow its
usage in CREATE TABLE, only ALTER TABLE.  It now works everywhere, and
it also allows using ALTER TABLE ONLY to add an uninherited CHECK
constraint, per discussion.

The pg_constraint column has accordingly been renamed connoinherit.

This commit partly reverts some of the changes in
61d81bd28dbec65a6b144e0cd3d0bfe25913c3ac, particularly some pg_dump and
psql bits, because now pg_get_constraintdef includes the necessary NO
INHERIT within the constraint definition.

Author: Nikhil Sontakke
Some tweaks by me

2 files changed, 13 insertions, 6 deletions

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c3039c81672..3af65accea8 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -907,7 +907,8 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
     and <literal>TABLESPACE</> actions never recurse to descendant tables;
     that is, they always act as though <literal>ONLY</> were specified.
     Adding a constraint can recurse only for <literal>CHECK</> constraints,
-    and is required to do so for such constraints.
+    and is required to do so for such constraints, except those that are
+    explicitely marked <literal>NO INHERIT</>.
    </para>
 
    <para>
@@ -1013,7 +1014,7 @@ ALTER TABLE distributors ADD CONSTRAINT zipchk CHECK (char_length(zipcode) = 5);
   <para>
    To add a check constraint only to a table and not to its children:
 <programlisting>
-ALTER TABLE ONLY distributors ADD CONSTRAINT zipchk CHECK (char_length(zipcode) = 5);
+ALTER TABLE distributors ADD CONSTRAINT zipchk CHECK NO INHERIT (char_length(zipcode) = 5);
 </programlisting>
    (The check constraint will not be inherited by future children, either.)
   </para>
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index bb932142102..4da6eea7589 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -47,7 +47,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
 [ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
 { NOT NULL |
   NULL |
-  CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) |
+  CHECK [ NO INHERIT ] ( <replaceable class="PARAMETER">expression</replaceable> ) |
   DEFAULT <replaceable>default_expr</replaceable> |
   UNIQUE <replaceable class="PARAMETER">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="PARAMETER">index_parameters</replaceable> |
@@ -58,7 +58,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
 <phrase>and <replaceable class="PARAMETER">table_constraint</replaceable> is:</phrase>
 
 [ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
-{ CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) |
+{ CHECK [ NO INHERIT ] ( <replaceable class="PARAMETER">expression</replaceable> ) |
   UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) <replaceable class="PARAMETER">index_parameters</replaceable> |
   PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) <replaceable class="PARAMETER">index_parameters</replaceable> |
   EXCLUDE [ USING <replaceable class="parameter">index_method</replaceable> ] ( <replaceable class="parameter">exclude_element</replaceable> WITH <replaceable class="parameter">operator</replaceable> [, ... ] ) <replaceable class="parameter">index_parameters</replaceable> [ WHERE ( <replaceable class="parameter">predicate</replaceable> ) ] |
@@ -299,7 +299,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
       contain identically-named <literal>CHECK</> constraints, these
       constraints must all have the same check expression, or an error will be
       reported.  Constraints having the same name and expression will
-      be merged into one copy.  Notice that an unnamed <literal>CHECK</>
+      be merged into one copy.  A constraint marked <literal>NO INHERIT</> in a
+      parent will not be considered.  Notice that an unnamed <literal>CHECK</>
       constraint in the new table will never be merged, since a unique name
       will always be chosen for it.
      </para>
@@ -415,7 +416,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
    </varlistentry>
 
    <varlistentry>
-    <term><literal>CHECK ( <replaceable class="PARAMETER">expression</replaceable> )</literal></term>
+    <term><literal>CHECK [ NO INHERIT ] ( <replaceable class="PARAMETER">expression</replaceable> )</literal></term>
     <listitem>
      <para>
       The <literal>CHECK</> clause specifies an expression producing a
@@ -434,6 +435,11 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
       subqueries nor refer to variables other than columns of the
       current row.
      </para>
+
+     <para>
+      A constraint marked with <literal>NO INHERIT</> will not propagate to
+      children tables.
+     </para>
     </listitem>
    </varlistentry>