Add ALTER TYPE ... ADD/DROP/ALTER/RENAME ATTRIBUTE

Like with tables, this also requires allowing the existence of
composite types with zero attributes.

reviewed by KaiGai Kohei

doc/src/sgml/ref/alter_type.sgml

@@ -23,9 +23,17 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-ALTER TYPE <replaceable class="PARAMETER">name</replaceable> RENAME TO <replaceable class="PARAMETER">new_name</replaceable>
+ALTER TYPE <replaceable class="PARAMETER">name</replaceable> <replaceable class="PARAMETER">action</replaceable> [, ... ]
 ALTER TYPE <replaceable class="PARAMETER">name</replaceable> OWNER TO <replaceable class="PARAMETER">new_owner</replaceable> 
+ALTER TYPE <replaceable class="PARAMETER">name</replaceable> RENAME ATTRIBUTE <replaceable class="PARAMETER">attribute_name</replaceable> TO <replaceable class="PARAMETER">new_attribute_name</replaceable>
+ALTER TYPE <replaceable class="PARAMETER">name</replaceable> RENAME TO <replaceable class="PARAMETER">new_name</replaceable>
 ALTER TYPE <replaceable class="PARAMETER">name</replaceable> SET SCHEMA <replaceable class="PARAMETER">new_schema</replaceable>
+
+<phrase>where <replaceable class="PARAMETER">action</replaceable> is one of:</phrase>
+
+    ADD ATTRIBUTE <replaceable class="PARAMETER">attribute_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable>
+    DROP ATTRIBUTE [ IF EXISTS ] <replaceable class="PARAMETER">attribute_name</replaceable>
+    ALTER ATTRIBUTE <replaceable class="PARAMETER">attribute_name</replaceable> [ SET DATA ] TYPE <replaceable class="PARAMETER">data_type</replaceable>
 </synopsis>
  </refsynopsisdiv>
 
@@ -34,6 +42,76 @@ ALTER TYPE <replaceable class="PARAMETER">name</replaceable> SET SCHEMA <replace
 
   <para>
    <command>ALTER TYPE</command> changes the definition of an existing type.
+   There are several subforms:
+
+  <variablelist>
+   <varlistentry>
+    <term><literal>ADD ATTRIBUTE</literal></term>
+    <listitem>
+     <para>
+      This form adds a new attribute to a composite type, using the same syntax as
+      <xref linkend="SQL-CREATETYPE">.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>DROP ATTRIBUTE [ IF EXISTS ]</literal></term>
+    <listitem>
+     <para>
+      This form drops an attribute from a composite type.
+      If <literal>IF EXISTS</literal> is specified and the attribute
+      does not exist, no error is thrown. In this case a notice
+      is issued instead.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>SET DATA TYPE</literal></term>
+    <listitem>
+     <para>
+      This form changes the type of an attribute of a composite type.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>OWNER</literal></term>
+    <listitem>
+     <para>
+      This form changes the owner of the type.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>RENAME</literal></term>
+    <listitem>
+     <para>
+      This form changes the name of the type or the name of an
+      individual attribute of a composite type.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>SET SCHEMA</literal></term>
+    <listitem>
+     <para>
+      This form moves the type into another schema.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+  </para>
+
+  <para>
+   The <literal>ADD ATTRIBUTE</literal>, <literal>DROP
+   ATTRIBUTE</literal>, and <literal>ALTER ATTRIBUTE</literal> actions
+   can be combined into a list of multiple alterations to apply in
+   parallel.  For example, it is possible to add several attributes
+   and/or alter the type of several attributes in a single command.
   </para>
 
   <para>
@@ -90,6 +168,34 @@ ALTER TYPE <replaceable class="PARAMETER">name</replaceable> SET SCHEMA <replace
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><replaceable class="PARAMETER">attribute_name</replaceable></term>
+      <listitem>
+       <para>
+        The name of the attribute to add, alter, or drop.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><replaceable class="PARAMETER">new_attribute_name</replaceable></term>
+      <listitem>
+       <para>
+        The new name of the attribute begin renamed.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><replaceable class="PARAMETER">data_type</replaceable></term>
+      <listitem>
+       <para>
+        The data type of the attribute to add, or the new type of the
+        attribute to alter.
+       </para>
+      </listitem>
+     </varlistentry>
+
     </variablelist>
    </para>
   </refsect1>
@@ -117,16 +223,32 @@ ALTER TYPE email OWNER TO joe;
    to <literal>customers</literal>:
 <programlisting>
 ALTER TYPE email SET SCHEMA customers;
+</programlisting>
+  </para>
+
+  <para>
+   To add a new attribute to a type:
+<programlisting>
+ALTER TYPE compfoo ADD ATTRIBUTE f3 int;
 </programlisting>
   </para>
  </refsect1>
 
  <refsect1>
   <title>Compatibility</title>
-    
+
   <para>
-   There is no <command>ALTER TYPE</command> statement in the SQL
-   standard.
+   The variants to add and drop attributes are part of the SQL
+   standard; the other variants are PostgreSQL extensions.
   </para>
  </refsect1>
+
+ <refsect1 id="SQL-ALTERTYPE-see-also">
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-createtype"></member>
+   <member><xref linkend="sql-droptype"></member>
+  </simplelist>
+ </refsect1>
 </refentry>

doc/src/sgml/ref/create_type.sgml

@@ -22,7 +22,7 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 CREATE TYPE <replaceable class="parameter">name</replaceable> AS
-    ( <replaceable class="PARAMETER">attribute_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [, ... ] )
+    ( [ <replaceable class="PARAMETER">attribute_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [, ... ] ] )
 
 CREATE TYPE <replaceable class="parameter">name</replaceable> AS ENUM
     ( [ '<replaceable class="parameter">label</replaceable>' [, ... ] ] )
@@ -768,10 +768,18 @@ CREATE TABLE big_objs (
   <title>Compatibility</title>
 
   <para>
-   This <command>CREATE TYPE</command> command is a
-   <productname>PostgreSQL</productname> extension.  There is a
-   <command>CREATE TYPE</command> statement in the <acronym>SQL</> standard
-   that is rather different in detail.
+   The first form of the <command>CREATE TYPE</command> command, which
+   creates a composite type, conforms to the <acronym>SQL</> standard.
+   The other forms are <productname>PostgreSQL</productname>
+   extensions.  The <command>CREATE TYPE</command> statement in
+   the <acronym>SQL</> standard also defines other forms that are not
+   implemented in <productname>PostgreSQL</>.
+  </para>
+
+  <para>
+   The ability to create a composite type with zero attributes is
+   a <productname>PostgreSQL</productname>-specific deviation from the
+   standard (analogous to <command>CREATE TABLE</command>).
   </para>
  </refsect1>
 
@@ -779,10 +787,10 @@ CREATE TABLE big_objs (
   <title>See Also</title>
 
   <simplelist type="inline">
-   <member><xref linkend="sql-createfunction"></member>
-   <member><xref linkend="sql-droptype"></member>
    <member><xref linkend="sql-altertype"></member>
    <member><xref linkend="sql-createdomain"></member>
+   <member><xref linkend="sql-createfunction"></member>
+   <member><xref linkend="sql-droptype"></member>
   </simplelist>
  </refsect1>
 

doc/src/sgml/ref/drop_type.sgml

@@ -97,7 +97,7 @@ DROP TYPE box;
    This command is similar to the corresponding command in the SQL
    standard, apart from the <literal>IF EXISTS</>
    option, which is a <productname>PostgreSQL</> extension.
-   But note that the <command>CREATE TYPE</command> command
+   But note that much of the <command>CREATE TYPE</command> command
    and the data type extension mechanisms in
    <productname>PostgreSQL</productname> differ from the SQL standard.
   </para>
@@ -107,8 +107,8 @@ DROP TYPE box;
   <title>See Also</title>
 
   <simplelist type="inline">
-   <member><xref linkend="sql-createtype"></member>
    <member><xref linkend="sql-altertype"></member>
+   <member><xref linkend="sql-createtype"></member>
   </simplelist>
  </refsect1>
 

src/backend/commands/alter.c

@@ -89,6 +89,7 @@ ExecRenameStmt(RenameStmt *stmt)
 		case OBJECT_VIEW:
 		case OBJECT_INDEX:
 		case OBJECT_COLUMN:
+		case OBJECT_ATTRIBUTE:
 		case OBJECT_TRIGGER:
 			{
 				Oid			relid;
@@ -123,6 +124,7 @@ ExecRenameStmt(RenameStmt *stmt)
 							break;
 						}
 					case OBJECT_COLUMN:
+					case OBJECT_ATTRIBUTE:
 						renameatt(relid,
 								  stmt->subname,		/* old att name */
 								  stmt->newname,		/* new att name */

src/backend/commands/typecmds.c

@@ -1508,11 +1508,6 @@ DefineCompositeType(const RangeVar *typevar, List *coldeflist)
 	Oid			typeNamespace;
 	Oid			relid;
 
-	if (coldeflist == NIL)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-				 errmsg("composite type must have at least one attribute")));
-
 	/*
 	 * now set the parameters for keys/inheritance etc. All of these are
 	 * uninteresting for composite types...

src/backend/parser/gram.y

@@ -131,6 +131,7 @@ static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args,
 						 List *args, int location);
 static List *mergeTableFuncParameters(List *func_args, List *columns);
 static TypeName *TableFuncTypeName(List *columns);
+static RangeVar *makeRangeVarFromAnyName(List *names, int position, core_yyscan_t yyscanner);
 
 %}
 
@@ -184,7 +185,7 @@ static TypeName *TableFuncTypeName(List *columns);
 		AlterDatabaseStmt AlterDatabaseSetStmt AlterDomainStmt AlterFdwStmt
 		AlterForeignServerStmt AlterGroupStmt
 		AlterObjectSchemaStmt AlterOwnerStmt AlterSeqStmt AlterTableStmt
-		AlterUserStmt AlterUserMappingStmt AlterUserSetStmt
+		AlterCompositeTypeStmt AlterUserStmt AlterUserMappingStmt AlterUserSetStmt
 		AlterRoleStmt AlterRoleSetStmt
 		AlterDefaultPrivilegesStmt DefACLAction
 		AnalyzeStmt ClosePortalStmt ClusterStmt CommentStmt
@@ -218,8 +219,8 @@ static TypeName *TableFuncTypeName(List *columns);
 %type <node>	alter_column_default opclass_item opclass_drop alter_using
 %type <ival>	add_drop opt_asc_desc opt_nulls_order
 
-%type <node>	alter_table_cmd
-%type <list>	alter_table_cmds
+%type <node>	alter_table_cmd alter_type_cmd
+%type <list>	alter_table_cmds alter_type_cmds
 
 %type <dbehavior>	opt_drop_behavior
 
@@ -295,7 +296,7 @@ static TypeName *TableFuncTypeName(List *columns);
 				reloption_list group_clause TriggerFuncArgs select_limit
 				opt_select_limit opclass_item_list opclass_drop_list
 				opt_opfamily transaction_mode_list_or_empty
-				TableFuncElementList opt_type_modifiers
+				OptTableFuncElementList TableFuncElementList opt_type_modifiers
 				prep_type_clause
 				execute_param_clause using_clause returning_clause
 				opt_enum_val_list enum_val_list table_func_column_list
@@ -462,7 +463,7 @@ static TypeName *TableFuncTypeName(List *columns);
 /* ordinary key words in alphabetical order */
 %token <keyword> ABORT_P ABSOLUTE_P ACCESS ACTION ADD_P ADMIN AFTER
 	AGGREGATE ALL ALSO ALTER ALWAYS ANALYSE ANALYZE AND ANY ARRAY AS ASC
-	ASSERTION ASSIGNMENT ASYMMETRIC AT AUTHORIZATION
+	ASSERTION ASSIGNMENT ASYMMETRIC AT ATTRIBUTE AUTHORIZATION
 
 	BACKWARD BEFORE BEGIN_P BETWEEN BIGINT BINARY BIT
 	BOOLEAN_P BOTH BY
@@ -657,6 +658,7 @@ stmt :
 			| AlterOwnerStmt
 			| AlterSeqStmt
 			| AlterTableStmt
+			| AlterCompositeTypeStmt
 			| AlterRoleSetStmt
 			| AlterRoleStmt
 			| AlterTSConfigurationStmt
@@ -1968,6 +1970,72 @@ reloption_elem:
 		;
 
 
+/*****************************************************************************
+ *
+ *	ALTER TYPE
+ *
+ * really variants of the ALTER TABLE subcommands with different spellings
+ *****************************************************************************/
+
+AlterCompositeTypeStmt:
+			ALTER TYPE_P any_name alter_type_cmds
+				{
+					AlterTableStmt *n = makeNode(AlterTableStmt);
+
+					/* can't use qualified_name, sigh */
+					n->relation = makeRangeVarFromAnyName($3, @3, yyscanner);
+					n->cmds = $4;
+					n->relkind = OBJECT_TYPE;
+					$$ = (Node *)n;
+				}
+			;
+
+alter_type_cmds:
+			alter_type_cmd							{ $$ = list_make1($1); }
+			| alter_type_cmds ',' alter_type_cmd	{ $$ = lappend($1, $3); }
+		;
+
+alter_type_cmd:
+			/* ALTER TYPE <name> ADD ATTRIBUTE <coldef> */
+			ADD_P ATTRIBUTE TableFuncElement
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_AddColumn;
+					n->def = $3;
+					$$ = (Node *)n;
+				}
+			/* ALTER TYPE <name> DROP ATTRIBUTE IF EXISTS <attname> */
+			| DROP ATTRIBUTE IF_P EXISTS ColId
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropColumn;
+					n->name = $5;
+					n->behavior = DROP_RESTRICT; /* currently no effect */
+					n->missing_ok = TRUE;
+					$$ = (Node *)n;
+				}
+			/* ALTER TYPE <name> DROP ATTRIBUTE <attname> */
+			| DROP ATTRIBUTE ColId opt_drop_behavior
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropColumn;
+					n->name = $3;
+					n->behavior = DROP_RESTRICT; /* currently no effect */
+					n->missing_ok = FALSE;
+					$$ = (Node *)n;
+				}
+			/* ALTER TYPE <name> ALTER ATTRIBUTE <attname> [SET DATA] TYPE <typename> */
+			| ALTER ATTRIBUTE ColId opt_set_data TYPE_P Typename
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_AlterColumnType;
+					n->name = $3;
+					n->def = (Node *) $6;
+					$$ = (Node *)n;
+				}
+		;
+
+
 /*****************************************************************************
  *
  *		QUERY :
@@ -3678,39 +3746,12 @@ DefineStmt:
 					n->definition = NIL;
 					$$ = (Node *)n;
 				}
-			| CREATE TYPE_P any_name AS '(' TableFuncElementList ')'
+			| CREATE TYPE_P any_name AS '(' OptTableFuncElementList ')'
 				{
 					CompositeTypeStmt *n = makeNode(CompositeTypeStmt);
-					RangeVar *r = makeNode(RangeVar);
 
 					/* can't use qualified_name, sigh */
-					switch (list_length($3))
-					{
-						case 1:
-							r->catalogname = NULL;
-							r->schemaname = NULL;
-							r->relname = strVal(linitial($3));
-							break;
-						case 2:
-							r->catalogname = NULL;
-							r->schemaname = strVal(linitial($3));
-							r->relname = strVal(lsecond($3));
-							break;
-						case 3:
-							r->catalogname = strVal(linitial($3));
-							r->schemaname = strVal(lsecond($3));
-							r->relname = strVal(lthird($3));
-							break;
-						default:
-							ereport(ERROR,
-									(errcode(ERRCODE_SYNTAX_ERROR),
-									 errmsg("improper qualified name (too many dotted names): %s",
-											NameListToString($3)),
-											parser_errposition(@3)));
-							break;
-					}
-					r->location = @3;
-					n->typevar = r;
+					n->typevar = makeRangeVarFromAnyName($3, @3, yyscanner);
 					n->coldeflist = $6;
 					$$ = (Node *)n;
 				}
@@ -5836,6 +5877,15 @@ RenameStmt: ALTER AGGREGATE func_name aggr_args RENAME TO name
 					n->newname = $6;
 					$$ = (Node *)n;
 				}
+			| ALTER TYPE_P any_name RENAME ATTRIBUTE name TO name
+				{
+					RenameStmt *n = makeNode(RenameStmt);
+					n->renameType = OBJECT_ATTRIBUTE;
+					n->relation = makeRangeVarFromAnyName($3, @3, yyscanner);
+					n->subname = $6;
+					n->newname = $8;
+					$$ = (Node *)n;
+				}
 		;
 
 opt_column: COLUMN									{ $$ = COLUMN; }
@@ -8216,6 +8266,11 @@ where_or_current_clause:
 		;
 
 
+OptTableFuncElementList:
+			TableFuncElementList				{ $$ = $1; }
+			| /*EMPTY*/							{ $$ = NIL; }
+		;
+
 TableFuncElementList:
 			TableFuncElement
 				{
@@ -10897,6 +10952,7 @@ unreserved_keyword:
 			| ASSERTION
 			| ASSIGNMENT
 			| AT
+			| ATTRIBUTE
 			| BACKWARD
 			| BEFORE
 			| BEGIN_P
@@ -11857,6 +11913,47 @@ TableFuncTypeName(List *columns)
 	return result;
 }
 
+/*
+ * Convert a list of (dotted) names to a RangeVar (like
+ * makeRangeVarFromNameList, but with position support).  The
+ * "AnyName" refers to the any_name production in the grammar.
+ */
+static RangeVar *
+makeRangeVarFromAnyName(List *names, int position, core_yyscan_t yyscanner)
+{
+	RangeVar *r = makeNode(RangeVar);
+
+	switch (list_length(names))
+	{
+		case 1:
+			r->catalogname = NULL;
+			r->schemaname = NULL;
+			r->relname = strVal(linitial(names));
+			break;
+		case 2:
+			r->catalogname = NULL;
+			r->schemaname = strVal(linitial(names));
+			r->relname = strVal(lsecond(names));
+			break;
+		case 3:
+			r->catalogname = strVal(linitial(names));;
+			r->schemaname = strVal(lsecond(names));
+			r->relname = strVal(lthird(names));
+			break;
+		default:
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("improper qualified name (too many dotted names): %s",
+							NameListToString(names)),
+					 parser_errposition(position)));
+			break;
+	}
+
+	r->location = position;
+
+	return r;
+}
+
 /*
  * Must undefine this stuff before including scan.c, since it has different
  * definitions for these macros.

src/backend/parser/parse_utilcmd.c

@@ -839,6 +839,9 @@ transformOfType(ParseState *pstate, CreateStmtContext *cxt, TypeName *ofTypename
 		Form_pg_attribute attr = tupdesc->attrs[i];
 		ColumnDef  *n = makeNode(ColumnDef);
 
+		if (attr->attisdropped)
+			continue;
+
 		n->colname = pstrdup(NameStr(attr->attname));
 		n->typeName = makeTypeNameFromOid(attr->atttypid, attr->atttypmod);
 		n->constraints = NULL;

src/backend/tcop/utility.c

@@ -1657,6 +1657,7 @@ CreateCommandTag(Node *parsetree)
 				case OBJECT_TSCONFIGURATION:
 					tag = "ALTER TEXT SEARCH CONFIGURATION";
 					break;
+				case OBJECT_ATTRIBUTE:
 				case OBJECT_TYPE:
 					tag = "ALTER TYPE";
 					break;
@@ -1780,6 +1781,9 @@ CreateCommandTag(Node *parsetree)
 				case OBJECT_SEQUENCE:
 					tag = "ALTER SEQUENCE";
 					break;
+				case OBJECT_TYPE:
+					tag = "ALTER TYPE";
+					break;
 				case OBJECT_VIEW:
 					tag = "ALTER VIEW";
 					break;

src/bin/pg_dump/pg_dump.c

@@ -7249,13 +7249,7 @@ dumpCompositeType(Archive *fout, TypeInfo *tyinfo)
 	res = PQexec(g_conn, query->data);
 	check_sql_result(res, g_conn, query->data, PGRES_TUPLES_OK);
 
-	/* Expecting at least a single result */
 	ntups = PQntuples(res);
-	if (ntups < 1)
-	{
-		write_msg(NULL, "query returned no rows: %s\n", query->data);
-		exit_nicely();
-	}
 
 	i_attname = PQfnumber(res, "attname");
 	i_atttypdefn = PQfnumber(res, "atttypdefn");
@@ -7356,12 +7350,12 @@ dumpCompositeTypeColComments(Archive *fout, TypeInfo *tyinfo)
 	res = PQexec(g_conn, query->data);
 	check_sql_result(res, g_conn, query->data, PGRES_TUPLES_OK);
 
-	/* Expecting at least a single result */
 	ntups = PQntuples(res);
 	if (ntups < 1)
 	{
-		write_msg(NULL, "query returned no rows: %s\n", query->data);
-		exit_nicely();
+		PQclear(res);
+		destroyPQExpBuffer(query);
+		return;
 	}
 
 	pgClassOid = atooid(PQgetvalue(res, 0, PQfnumber(res, "tableoid")));

src/bin/psql/tab-complete.c

@@ -1253,15 +1253,45 @@ psql_completion(char *text, int start, int end)
 		COMPLETE_WITH_LIST(list_ALTERTEXTSEARCH3);
 	}
 
-	/* complete ALTER TYPE <foo> with OWNER TO, SET SCHEMA */
+	/* complete ALTER TYPE <foo> with actions */
 	else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
 			 pg_strcasecmp(prev2_wd, "TYPE") == 0)
 	{
 		static const char *const list_ALTERTYPE[] =
-		{"OWNER TO", "RENAME TO", "SET SCHEMA", NULL};
+		{"ADD ATTRIBUTE", "ALTER ATTRIBUTE", "DROP ATTRIBUTE",
+		 "OWNER TO", "RENAME", "SET SCHEMA", NULL};
 
 		COMPLETE_WITH_LIST(list_ALTERTYPE);
 	}
+	/* ALTER TYPE <foo> RENAME  */
+	else if (pg_strcasecmp(prev4_wd, "ALTER") == 0 &&
+			 pg_strcasecmp(prev3_wd, "TYPE") == 0 &&
+			 pg_strcasecmp(prev_wd, "RENAME") == 0)
+	{
+		static const char *const list_ALTERTYPE[] =
+		{"ATTRIBUTE", "TO", NULL};
+
+		COMPLETE_WITH_LIST(list_ALTERTYPE);
+	}
+	/* ALTER TYPE xxx RENAME ATTRIBUTE yyy */
+	else if (pg_strcasecmp(prev5_wd, "TYPE") == 0 &&
+			 pg_strcasecmp(prev3_wd, "RENAME") == 0 &&
+			 pg_strcasecmp(prev2_wd, "ATTRIBUTE") == 0)
+		COMPLETE_WITH_CONST("TO");
+
+	/* If we have TYPE <sth> ALTER/DROP/RENAME ATTRIBUTE, provide list of attributes */
+	else if (pg_strcasecmp(prev4_wd, "TYPE") == 0 &&
+			 (pg_strcasecmp(prev2_wd, "ALTER") == 0 ||
+			  pg_strcasecmp(prev2_wd, "DROP") == 0 ||
+			  pg_strcasecmp(prev2_wd, "RENAME") == 0) &&
+			 pg_strcasecmp(prev_wd, "ATTRIBUTE") == 0)
+		COMPLETE_WITH_ATTR(prev3_wd, "");
+	/* ALTER TYPE ALTER ATTRIBUTE <foo> */
+	else if ((pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
+			  pg_strcasecmp(prev2_wd, "ATTRIBUTE") == 0))
+	{
+		COMPLETE_WITH_CONST("TYPE");
+	}
 	/* complete ALTER GROUP <foo> */
 	else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
 			 pg_strcasecmp(prev2_wd, "GROUP") == 0)

src/include/nodes/parsenodes.h

@@ -1046,6 +1046,7 @@ typedef struct SetOperationStmt
 typedef enum ObjectType
 {
 	OBJECT_AGGREGATE,
+	OBJECT_ATTRIBUTE,			/* type's attribute, when distinct from column */
 	OBJECT_CAST,
 	OBJECT_COLUMN,
 	OBJECT_CONSTRAINT,

src/include/parser/kwlist.h

@@ -49,6 +49,7 @@ PG_KEYWORD("assertion", ASSERTION, UNRESERVED_KEYWORD)
 PG_KEYWORD("assignment", ASSIGNMENT, UNRESERVED_KEYWORD)
 PG_KEYWORD("asymmetric", ASYMMETRIC, RESERVED_KEYWORD)
 PG_KEYWORD("at", AT, UNRESERVED_KEYWORD)
+PG_KEYWORD("attribute", ATTRIBUTE, UNRESERVED_KEYWORD)
 PG_KEYWORD("authorization", AUTHORIZATION, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("backward", BACKWARD, UNRESERVED_KEYWORD)
 PG_KEYWORD("before", BEFORE, UNRESERVED_KEYWORD)

src/test/regress/expected/alter_table.out

@@ -854,7 +854,7 @@ select * from myview;
 (0 rows)
 
 alter table myview drop d;
-ERROR:  "myview" is not a table
+ERROR:  "myview" is not a table or composite type
 drop view myview;
 -- test some commands to make sure they fail on the dropped column
 analyze atacc1(a);
@@ -1472,6 +1472,11 @@ select * from another;
 (3 rows)
 
 drop table another;
+-- table's row type
+create table tab1 (a int, b text);
+create table tab2 (x int, y tab1);
+alter table tab1 alter column b type varchar; -- fails
+ERROR:  cannot alter table "tab1" because column "tab2"."y" uses its rowtype
 --
 -- lock levels
 --
@@ -1683,3 +1688,85 @@ drop cascades to view alter2.v1
 drop cascades to function alter2.plus1(integer)
 drop cascades to type alter2.posint
 drop cascades to type alter2.ctype
+--
+-- composite types
+--
+CREATE TYPE test_type AS (a int);
+\d test_type
+Composite type "public.test_type"
+ Column |  Type   
+--------+---------
+ a      | integer
+
+ALTER TYPE nosuchtype ADD ATTRIBUTE b text; -- fails
+ERROR:  relation "nosuchtype" does not exist
+ALTER TYPE test_type ADD ATTRIBUTE b text;
+\d test_type
+Composite type "public.test_type"
+ Column |  Type   
+--------+---------
+ a      | integer
+ b      | text
+
+ALTER TYPE test_type ADD ATTRIBUTE b text; -- fails
+ERROR:  column "b" of relation "test_type" already exists
+ALTER TYPE test_type ALTER ATTRIBUTE b SET DATA TYPE varchar;
+\d test_type
+Composite type "public.test_type"
+ Column |       Type        
+--------+-------------------
+ a      | integer
+ b      | character varying
+
+ALTER TYPE test_type ALTER ATTRIBUTE b SET DATA TYPE integer;
+\d test_type
+Composite type "public.test_type"
+ Column |  Type   
+--------+---------
+ a      | integer
+ b      | integer
+
+ALTER TYPE test_type DROP ATTRIBUTE b;
+\d test_type
+Composite type "public.test_type"
+ Column |  Type   
+--------+---------
+ a      | integer
+
+ALTER TYPE test_type DROP ATTRIBUTE c; -- fails
+ERROR:  column "c" of relation "test_type" does not exist
+ALTER TYPE test_type DROP ATTRIBUTE IF EXISTS c;
+NOTICE:  column "c" of relation "test_type" does not exist, skipping
+ALTER TYPE test_type DROP ATTRIBUTE a, ADD ATTRIBUTE d boolean;
+\d test_type
+Composite type "public.test_type"
+ Column |  Type   
+--------+---------
+ d      | boolean
+
+ALTER TYPE test_type RENAME ATTRIBUTE a TO aa;
+ERROR:  column "a" does not exist
+ALTER TYPE test_type RENAME ATTRIBUTE d TO dd;
+\d test_type
+Composite type "public.test_type"
+ Column |  Type   
+--------+---------
+ dd     | boolean
+
+DROP TYPE test_type;
+CREATE TYPE test_type1 AS (a int, b text);
+CREATE TABLE test_tbl1 (x int, y test_type1);
+ALTER TYPE test_type1 ALTER ATTRIBUTE b TYPE varchar; -- fails
+ERROR:  cannot alter type "test_type1" because column "test_tbl1"."y" uses it
+CREATE TYPE test_type2 AS (a int, b text);
+CREATE TABLE test_tbl2 OF test_type2;
+ALTER TYPE test_type2 ADD ATTRIBUTE c text; -- fails
+ERROR:  cannot alter type "test_type2" because it is the type of a typed table
+ALTER TYPE test_type2 ALTER ATTRIBUTE b TYPE varchar; -- fails
+ERROR:  cannot alter type "test_type2" because it is the type of a typed table
+ALTER TYPE test_type2 DROP ATTRIBUTE b; -- fails
+ERROR:  cannot alter type "test_type2" because it is the type of a typed table
+ALTER TYPE test_type2 RENAME ATTRIBUTE b TO bb; -- fails
+ERROR:  cannot alter type "test_type2" because it is the type of a typed table
+CREATE TYPE test_type_empty AS ();
+DROP TYPE test_type_empty;

src/test/regress/sql/alter_table.sql

@@ -1090,6 +1090,11 @@ select * from another;
 
 drop table another;
 
+-- table's row type
+create table tab1 (a int, b text);
+create table tab2 (x int, y tab1);
+alter table tab1 alter column b type varchar; -- fails
+
 --
 -- lock levels
 --
@@ -1224,3 +1229,53 @@ select alter2.plus1(41);
 
 -- clean up
 drop schema alter2 cascade;
+
+--
+-- composite types
+--
+
+CREATE TYPE test_type AS (a int);
+\d test_type
+
+ALTER TYPE nosuchtype ADD ATTRIBUTE b text; -- fails
+
+ALTER TYPE test_type ADD ATTRIBUTE b text;
+\d test_type
+
+ALTER TYPE test_type ADD ATTRIBUTE b text; -- fails
+
+ALTER TYPE test_type ALTER ATTRIBUTE b SET DATA TYPE varchar;
+\d test_type
+
+ALTER TYPE test_type ALTER ATTRIBUTE b SET DATA TYPE integer;
+\d test_type
+
+ALTER TYPE test_type DROP ATTRIBUTE b;
+\d test_type
+
+ALTER TYPE test_type DROP ATTRIBUTE c; -- fails
+
+ALTER TYPE test_type DROP ATTRIBUTE IF EXISTS c;
+
+ALTER TYPE test_type DROP ATTRIBUTE a, ADD ATTRIBUTE d boolean;
+\d test_type
+
+ALTER TYPE test_type RENAME ATTRIBUTE a TO aa;
+ALTER TYPE test_type RENAME ATTRIBUTE d TO dd;
+\d test_type
+
+DROP TYPE test_type;
+
+CREATE TYPE test_type1 AS (a int, b text);
+CREATE TABLE test_tbl1 (x int, y test_type1);
+ALTER TYPE test_type1 ALTER ATTRIBUTE b TYPE varchar; -- fails
+
+CREATE TYPE test_type2 AS (a int, b text);
+CREATE TABLE test_tbl2 OF test_type2;
+ALTER TYPE test_type2 ADD ATTRIBUTE c text; -- fails
+ALTER TYPE test_type2 ALTER ATTRIBUTE b TYPE varchar; -- fails
+ALTER TYPE test_type2 DROP ATTRIBUTE b; -- fails
+ALTER TYPE test_type2 RENAME ATTRIBUTE b TO bb; -- fails
+
+CREATE TYPE test_type_empty AS ();
+DROP TYPE test_type_empty;