Improve ALTER TABLE synopsis

Add into the ALTER TABLE synopsis the definition of
partition_bound_spec, column_constraint, index_parameters and
exclude_element.

Initial patch by Lætitia Avrot, with further improvements by Amit
Langote and Thomas Munro.

Discussion: https://postgr.es/m/flat/27ec4df3-d1ab-3411-f87f-647f944897e1%40lab.ntt.co.jp

doc/src/sgml/ref/alter_table.sgml

@@ -85,6 +85,27 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     OWNER TO { <replaceable class="parameter">new_owner</replaceable> | CURRENT_USER | SESSION_USER }
     REPLICA IDENTITY { DEFAULT | USING INDEX <replaceable class="parameter">index_name</replaceable> | FULL | NOTHING }
 
+<phrase>and <replaceable class="parameter">partition_bound_spec</replaceable> is:</phrase>
+
+IN ( { <replaceable class="parameter">numeric_literal</replaceable> | <replaceable class="parameter">string_literal</replaceable> | NULL } [, ...] ) |
+FROM ( { <replaceable class="parameter">numeric_literal</replaceable> | <replaceable class="parameter">string_literal</replaceable> | MINVALUE | MAXVALUE } [, ...] )
+  TO ( { <replaceable class="parameter">numeric_literal</replaceable> | <replaceable class="parameter">string_literal</replaceable> | MINVALUE | MAXVALUE } [, ...] ) |
+WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REMAINDER <replaceable class="parameter">numeric_literal</replaceable> )
+
+<phrase>and <replaceable class="parameter">column_constraint</replaceable> is:</phrase>
+
+[ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ]
+{ NOT NULL |
+  NULL |
+  CHECK ( <replaceable class="parameter">expression</replaceable> ) [ NO INHERIT ] |
+  DEFAULT <replaceable>default_expr</replaceable> |
+  GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
+  UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
+  PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
+  REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
+    [ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ] }
+[ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
+
 <phrase>and <replaceable class="parameter">table_constraint</replaceable> is:</phrase>
 
 [ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ]
@@ -101,6 +122,16 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     [ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ]
     { UNIQUE | PRIMARY KEY } USING INDEX <replaceable class="parameter">index_name</replaceable>
     [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
+
+<phrase><replaceable class="parameter">index_parameters</replaceable> in <literal>UNIQUE</literal>, <literal>PRIMARY KEY</literal>, and <literal>EXCLUDE</literal> constraints are:</phrase>
+
+[ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
+[ USING INDEX TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
+
+<phrase><replaceable class="parameter">exclude_element</replaceable> in an <literal>EXCLUDE</literal> constraint is:</phrase>
+
+{ <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ <replaceable class="parameter">opclass</replaceable> ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ]
+
 </synopsis>
  </refsynopsisdiv>