Allow ALTER TABLE name {OF type | NOT OF}.

This syntax allows a standalone table to be made into a typed table,
or a typed table to be made standalone.  This is possibly a mildly
useful feature in its own right, but the real motivation for this
change is that we need it to make pg_upgrade work with typed tables.
This doesn't actually fix that problem, but it's necessary
infrastructure.

Noah Misch

doc/src/sgml/ref/alter_table.sgml

@@ -63,6 +63,8 @@ ALTER TABLE <replaceable class="PARAMETER">name</replaceable>
     RESET ( <replaceable class="PARAMETER">storage_parameter</replaceable> [, ... ] )
     INHERIT <replaceable class="PARAMETER">parent_table</replaceable>
     NO INHERIT <replaceable class="PARAMETER">parent_table</replaceable>
+    OF <replaceable class="PARAMETER">type_name</replaceable>
+    NOT OF
     OWNER TO <replaceable class="PARAMETER">new_owner</replaceable>
     SET TABLESPACE <replaceable class="PARAMETER">new_tablespace</replaceable>
 
@@ -490,6 +492,30 @@ ALTER TABLE <replaceable class="PARAMETER">name</replaceable>
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>OF <replaceable class="PARAMETER">type_name</replaceable></literal></term>
+    <listitem>
+     <para>
+      This form links the table to a composite type as though <command>CREATE
+      TABLE OF</> had formed it.  The table's list of column names and types
+      must precisely match that of the composite type; the presence of
+      an <literal>oid</> system column is permitted to differ.  The table must
+      not inherit from any other table.  These restrictions ensure
+      that <command>CREATE TABLE OF</> would permit an equivalent table
+      definition.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>NOT OF</literal></term>
+    <listitem>
+     <para>
+      This form dissociates a typed table from its type.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>OWNER</literal></term>
     <listitem>

src/backend/parser/gram.y

@@ -1933,6 +1933,23 @@ alter_table_cmd:
 					n->def = (Node *) $3;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> OF <type_name> */
+			| OF any_name
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					TypeName *def = makeTypeNameFromNameList($2);
+					def->location = @2;
+					n->subtype = AT_AddOf;
+					n->def = (Node *) def;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> NOT OF */
+			| NOT OF
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropOf;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> OWNER TO RoleId */
 			| OWNER TO RoleId
 				{

src/backend/parser/parse_utilcmd.c

@@ -825,35 +825,15 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
 	TupleDesc	tupdesc;
 	int			i;
 	Oid			ofTypeId;
-	bool		typeOk = false;
 
 	AssertArg(ofTypename);
 
 	tuple = typenameType(NULL, ofTypename, NULL);
+	check_of_type(tuple);
 	typ = (Form_pg_type) GETSTRUCT(tuple);
 	ofTypeId = HeapTupleGetOid(tuple);
 	ofTypename->typeOid = ofTypeId;		/* cached for later */
 
-	if (typ->typtype == TYPTYPE_COMPOSITE)
-	{
-		Relation	typeRelation;
-
-		Assert(OidIsValid(typ->typrelid));
-		typeRelation = relation_open(typ->typrelid, AccessShareLock);
-		typeOk = (typeRelation->rd_rel->relkind == RELKIND_COMPOSITE_TYPE);
-		/*
-		 * Close the parent rel, but keep our AccessShareLock on it until xact
-		 * commit.	That will prevent someone else from deleting or ALTERing
-		 * the type before the typed table creation commits.
-		 */
-		relation_close(typeRelation, NoLock);
-	}
-	if (!typeOk)
-		ereport(ERROR,
-				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-				 errmsg("type %s is not a composite type",
-						format_type_be(ofTypeId))));
-
 	tupdesc = lookup_rowtype_tupdesc(ofTypeId, -1);
 	for (i = 0; i < tupdesc->natts; i++)
 	{

src/include/commands/tablecmds.h

@@ -56,6 +56,8 @@ extern void find_composite_type_dependencies(Oid typeOid,
 								 Relation origRelation,
 								 const char *origTypeName);
 
+extern void check_of_type(HeapTuple typetuple);
+
 extern AttrNumber *varattnos_map(TupleDesc olddesc, TupleDesc newdesc);
 extern AttrNumber *varattnos_map_schema(TupleDesc old, List *schema);
 extern void change_varattnos_of_a_node(Node *node, const AttrNumber *newattno);

src/include/nodes/parsenodes.h

@@ -1219,6 +1219,8 @@ typedef enum AlterTableType
 	AT_DisableRule,				/* DISABLE RULE name */
 	AT_AddInherit,				/* INHERIT parent */
 	AT_DropInherit,				/* NO INHERIT parent */
+	AT_AddOf,					/* OF <type_name> */
+	AT_DropOf,					/* NOT OF */
 	AT_GenericOptions,			/* OPTIONS (...) */
 } AlterTableType;
 

src/test/regress/expected/alter_table.out

@@ -1942,3 +1942,41 @@ Typed table of type: test_type2
 
 CREATE TYPE test_type_empty AS ();
 DROP TYPE test_type_empty;
+--
+-- typed tables: OF / NOT OF
+--
+CREATE TYPE tt_t0 AS (z inet, x int, y numeric(8,2));
+ALTER TYPE tt_t0 DROP ATTRIBUTE z;
+CREATE TABLE tt0 (x int NOT NULL, y numeric(8,2));	-- OK
+CREATE TABLE tt1 (x int, y bigint);					-- wrong base type
+CREATE TABLE tt2 (x int, y numeric(9,2));			-- wrong typmod
+CREATE TABLE tt3 (y numeric(8,2), x int);			-- wrong column order
+CREATE TABLE tt4 (x int);							-- too few columns
+CREATE TABLE tt5 (x int, y numeric(8,2), z int);	-- too few columns
+CREATE TABLE tt6 () INHERITS (tt0);					-- can't have a parent
+CREATE TABLE tt7 (x int, q text, y numeric(8,2)) WITH OIDS;
+ALTER TABLE tt7 DROP q;								-- OK
+ALTER TABLE tt0 OF tt_t0;
+ALTER TABLE tt1 OF tt_t0;
+ERROR:  table "tt1" has different type for column "y"
+ALTER TABLE tt2 OF tt_t0;
+ERROR:  table "tt2" has different type for column "y"
+ALTER TABLE tt3 OF tt_t0;
+ERROR:  table has column "y" where type requires "x"
+ALTER TABLE tt4 OF tt_t0;
+ERROR:  table is missing column "y"
+ALTER TABLE tt5 OF tt_t0;
+ERROR:  table has extra column "z"
+ALTER TABLE tt6 OF tt_t0;
+ERROR:  typed tables cannot inherit
+ALTER TABLE tt7 OF tt_t0;
+CREATE TYPE tt_t1 AS (x int, y numeric(8,2));
+ALTER TABLE tt7 OF tt_t1;			-- reassign an already-typed table
+ALTER TABLE tt7 NOT OF;
+\d tt7
+        Table "public.tt7"
+ Column |     Type     | Modifiers 
+--------+--------------+-----------
+ x      | integer      | 
+ y      | numeric(8,2) | 
+

src/test/regress/sql/alter_table.sql

@@ -1369,3 +1369,33 @@ ALTER TYPE test_type2 RENAME ATTRIBUTE a TO aa CASCADE;
 
 CREATE TYPE test_type_empty AS ();
 DROP TYPE test_type_empty;
+
+--
+-- typed tables: OF / NOT OF
+--
+
+CREATE TYPE tt_t0 AS (z inet, x int, y numeric(8,2));
+ALTER TYPE tt_t0 DROP ATTRIBUTE z;
+CREATE TABLE tt0 (x int NOT NULL, y numeric(8,2));	-- OK
+CREATE TABLE tt1 (x int, y bigint);					-- wrong base type
+CREATE TABLE tt2 (x int, y numeric(9,2));			-- wrong typmod
+CREATE TABLE tt3 (y numeric(8,2), x int);			-- wrong column order
+CREATE TABLE tt4 (x int);							-- too few columns
+CREATE TABLE tt5 (x int, y numeric(8,2), z int);	-- too few columns
+CREATE TABLE tt6 () INHERITS (tt0);					-- can't have a parent
+CREATE TABLE tt7 (x int, q text, y numeric(8,2)) WITH OIDS;
+ALTER TABLE tt7 DROP q;								-- OK
+
+ALTER TABLE tt0 OF tt_t0;
+ALTER TABLE tt1 OF tt_t0;
+ALTER TABLE tt2 OF tt_t0;
+ALTER TABLE tt3 OF tt_t0;
+ALTER TABLE tt4 OF tt_t0;
+ALTER TABLE tt5 OF tt_t0;
+ALTER TABLE tt6 OF tt_t0;
+ALTER TABLE tt7 OF tt_t0;
+
+CREATE TYPE tt_t1 AS (x int, y numeric(8,2));
+ALTER TABLE tt7 OF tt_t1;			-- reassign an already-typed table
+ALTER TABLE tt7 NOT OF;
+\d tt7