Add new OID alias type regrole

The new type has the scope of whole the database cluster so it doesn't
behave the same as the existing OID alias types which have database
scope,
concerning object dependency. To avoid confusion constants of the new
type are prohibited from appearing where dependencies are made involving
it.

Also, add a note to the docs about possible MVCC violation and
optimization issues, which are general over the all reg* types.

Kyotaro Horiguchi

Author: adunstan

contrib/spi/insert_username.c

@@ -79,7 +79,7 @@ insert_username(PG_FUNCTION_ARGS)
 						args[0], relname)));
 
 	/* create fields containing name */
-	newval = CStringGetTextDatum(GetUserNameFromId(GetUserId()));
+	newval = CStringGetTextDatum(GetUserNameFromId(GetUserId(), false));
 
 	/* construct new tuple */
 	rettuple = SPI_modifytuple(rel, rettuple, 1, &attnum, &newval, NULL);

contrib/spi/timetravel.c

@@ -174,7 +174,7 @@ timetravel(PG_FUNCTION_ARGS)
 	}
 
 	/* create fields containing name */
-	newuser = CStringGetTextDatum(GetUserNameFromId(GetUserId()));
+	newuser = CStringGetTextDatum(GetUserNameFromId(GetUserId(), false));
 
 	nulltext = (Datum) NULL;
 

doc/src/sgml/datatype.sgml

@@ -4321,8 +4321,9 @@ SET xmloption TO { DOCUMENT | CONTENT };
     an object identifier.  There are also several alias types for
     <type>oid</>: <type>regproc</>, <type>regprocedure</>,
     <type>regoper</>, <type>regoperator</>, <type>regclass</>,
-    <type>regtype</>, <type>regconfig</>, and <type>regdictionary</>.
-    <xref linkend="datatype-oid-table"> shows an overview.
+    <type>regtype</>, <type>regrole</>, <type>regconfig</>, and
+    <type>regdictionary</>.  <xref linkend="datatype-oid-table"> shows
+    an overview.
    </para>
 
    <para>
@@ -4430,6 +4431,13 @@ SELECT * FROM pg_attribute
         <entry><literal>integer</></entry>
        </row>
 
+       <row>
+        <entry><type>regrole</></entry>
+        <entry><structname>pg_authid</></entry>
+        <entry>role name</entry>
+        <entry><literal>smithee</></entry>
+       </row>
+
        <row>
         <entry><type>regconfig</></entry>
         <entry><structname>pg_ts_config</></entry>
@@ -4448,7 +4456,8 @@ SELECT * FROM pg_attribute
     </table>
 
    <para>
-    All of the OID alias types accept schema-qualified names, and will
+    All of the OID alias types for objects grouped by namespace accept
+    schema-qualified names, and will
     display schema-qualified names on output if the object would not
     be found in the current search path without being qualified.
     The <type>regproc</> and <type>regoper</> alias types will only
@@ -4460,7 +4469,7 @@ SELECT * FROM pg_attribute
    </para>
 
    <para>
-    An additional property of the OID alias types is the creation of
+    An additional property of most of the OID alias types is the creation of
     dependencies.  If a
     constant of one of these types appears in a stored expression
     (such as a column default expression or view), it creates a dependency
@@ -4470,7 +4479,17 @@ SELECT * FROM pg_attribute
     understands that the default expression depends on the sequence
     <literal>my_seq</>; the system will not let the sequence be dropped
     without first removing the default expression.
+    <type>regrole</> is the only exception for the property. Constants of this
+    type are not allowed in such expressions.
+   </para>
+
+   <note>
+   <para>
+    The OID alias types do not completely follow transaction isolation
+    rules. The planner also treats them as simple constants, which may
+    result in sub-optimal planning.
    </para>
+   </note>
 
    <para>
     Another identifier type used by the system is <type>xid</>, or transaction

src/backend/bootstrap/bootstrap.c

@@ -113,6 +113,8 @@ static const struct typinfo TypInfo[] = {
 	F_REGPROCIN, F_REGPROCOUT},
 	{"regtype", REGTYPEOID, 0, 4, true, 'i', 'p', InvalidOid,
 	F_REGTYPEIN, F_REGTYPEOUT},
+	{"regrole", REGROLEOID, 0, 4, true, 'i', 'p', InvalidOid,
+	F_REGROLEIN, F_REGROLEOUT},
 	{"text", TEXTOID, 0, -1, false, 'i', 'x', DEFAULT_COLLATION_OID,
 	F_TEXTIN, F_TEXTOUT},
 	{"oid", OIDOID, 0, 4, true, 'i', 'p', InvalidOid,

src/backend/catalog/dependency.c

@@ -1602,6 +1602,16 @@ find_expr_references_walker(Node *node,
 						add_object_address(OCLASS_TSDICT, objoid, 0,
 										   context->addrs);
 					break;
+
+				/*
+				 * Dependencies for regrole should be shared among all
+				 * databases, so explicitly inhibit to have dependencies.
+				 */
+				case REGROLEOID:
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("constant of the type \'regrole\' cannot be used here")));
+					break;
 			}
 		}
 		return false;

src/backend/catalog/objectaddress.c

@@ -2818,7 +2818,7 @@ getObjectDescription(const ObjectAddress *object)
 		case OCLASS_ROLE:
 			{
 				appendStringInfo(&buffer, _("role %s"),
-								 GetUserNameFromId(object->objectId));
+								 GetUserNameFromId(object->objectId, false));
 				break;
 			}
 
@@ -2884,7 +2884,7 @@ getObjectDescription(const ObjectAddress *object)
 				ReleaseSysCache(tup);
 
 				if (OidIsValid(useid))
-					usename = GetUserNameFromId(useid);
+					usename = GetUserNameFromId(useid, false);
 				else
 					usename = "public";
 
@@ -2924,28 +2924,28 @@ getObjectDescription(const ObjectAddress *object)
 					case DEFACLOBJ_RELATION:
 						appendStringInfo(&buffer,
 										 _("default privileges on new relations belonging to role %s"),
-									  GetUserNameFromId(defacl->defaclrole));
+									  GetUserNameFromId(defacl->defaclrole, false));
 						break;
 					case DEFACLOBJ_SEQUENCE:
 						appendStringInfo(&buffer,
 										 _("default privileges on new sequences belonging to role %s"),
-									  GetUserNameFromId(defacl->defaclrole));
+									  GetUserNameFromId(defacl->defaclrole, false));
 						break;
 					case DEFACLOBJ_FUNCTION:
 						appendStringInfo(&buffer,
 										 _("default privileges on new functions belonging to role %s"),
-									  GetUserNameFromId(defacl->defaclrole));
+									  GetUserNameFromId(defacl->defaclrole, false));
 						break;
 					case DEFACLOBJ_TYPE:
 						appendStringInfo(&buffer,
 										 _("default privileges on new types belonging to role %s"),
-									  GetUserNameFromId(defacl->defaclrole));
+									  GetUserNameFromId(defacl->defaclrole, false));
 						break;
 					default:
 						/* shouldn't get here */
 						appendStringInfo(&buffer,
 								_("default privileges belonging to role %s"),
-									  GetUserNameFromId(defacl->defaclrole));
+									  GetUserNameFromId(defacl->defaclrole, false));
 						break;
 				}
 
@@ -4214,7 +4214,7 @@ getObjectIdentityParts(const ObjectAddress *object,
 			{
 				char	   *username;
 
-				username = GetUserNameFromId(object->objectId);
+				username = GetUserNameFromId(object->objectId, false);
 				if (objname)
 					*objname = list_make1(username);
 				appendStringInfoString(&buffer,
@@ -4295,7 +4295,7 @@ getObjectIdentityParts(const ObjectAddress *object,
 				ReleaseSysCache(tup);
 
 				if (OidIsValid(useid))
-					usename = GetUserNameFromId(useid);
+					usename = GetUserNameFromId(useid, false);
 				else
 					usename = "public";
 
@@ -4339,7 +4339,7 @@ getObjectIdentityParts(const ObjectAddress *object,
 
 				defacl = (Form_pg_default_acl) GETSTRUCT(tup);
 
-				username = GetUserNameFromId(defacl->defaclrole);
+				username = GetUserNameFromId(defacl->defaclrole, false);
 				appendStringInfo(&buffer,
 								 "for role %s",
 								 quote_identifier(username));

src/backend/utils/adt/acl.c

@@ -4878,7 +4878,7 @@ check_is_member_of_role(Oid member, Oid role)
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 				 errmsg("must be member of role \"%s\"",
-						GetUserNameFromId(role))));
+						GetUserNameFromId(role, false))));
 }
 
 /*

src/backend/utils/adt/name.c

@@ -263,13 +263,13 @@ namestrcmp(Name name, const char *str)
 Datum
 current_user(PG_FUNCTION_ARGS)
 {
-	PG_RETURN_DATUM(DirectFunctionCall1(namein, CStringGetDatum(GetUserNameFromId(GetUserId()))));
+	PG_RETURN_DATUM(DirectFunctionCall1(namein, CStringGetDatum(GetUserNameFromId(GetUserId(), false))));
 }
 
 Datum
 session_user(PG_FUNCTION_ARGS)
 {
-	PG_RETURN_DATUM(DirectFunctionCall1(namein, CStringGetDatum(GetUserNameFromId(GetSessionUserId()))));
+	PG_RETURN_DATUM(DirectFunctionCall1(namein, CStringGetDatum(GetUserNameFromId(GetSessionUserId(), false))));
 }
 
 

src/backend/utils/adt/regproc.c

@@ -40,6 +40,7 @@
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
 #include "utils/tqual.h"
+#include "utils/acl.h"
 
 static char *format_operator_internal(Oid operator_oid, bool force_qualify);
 static char *format_procedure_internal(Oid procedure_oid, bool force_qualify);
@@ -1553,6 +1554,109 @@ regdictionarysend(PG_FUNCTION_ARGS)
 	return oidsend(fcinfo);
 }
 
+/*
+ * regrolein	- converts "rolename" to role OID
+ *
+ * We also accept a numeric OID, for symmetry with the output routine.
+ *
+ * '-' signifies unknown (OID 0).  In all other cases, the input must
+ * match an existing pg_authid entry.
+ *
+ * This function is not needed in bootstrap mode, so we don't worry about
+ * making it work then.
+ */
+Datum
+regrolein(PG_FUNCTION_ARGS)
+{
+	char	   *role_name_or_oid = PG_GETARG_CSTRING(0);
+	Oid			result;
+
+	/* '-' ? */
+	if (strcmp(role_name_or_oid, "-") == 0)
+		PG_RETURN_OID(InvalidOid);
+
+	/* Numeric OID? */
+	if (role_name_or_oid[0] >= '0' &&
+		role_name_or_oid[0] <= '9' &&
+		strspn(role_name_or_oid, "0123456789") == strlen(role_name_or_oid))
+	{
+		result = DatumGetObjectId(DirectFunctionCall1(oidin,
+										 CStringGetDatum(role_name_or_oid)));
+		PG_RETURN_OID(result);
+	}
+
+	/* Normal case: see if the name matches any pg_authid entry. */
+	result = get_role_oid(role_name_or_oid, false);
+
+	PG_RETURN_OID(result);
+}
+
+/*
+ * to_regrole		- converts "rolename" to role OID
+ *
+ * If the name is not found, we return NULL.
+ */
+Datum
+to_regrole(PG_FUNCTION_ARGS)
+{
+	char	   *role_name = PG_GETARG_CSTRING(0);
+	Oid			result;
+
+	result = get_role_oid(role_name, true);
+
+	if (OidIsValid(result))
+		PG_RETURN_OID(result);
+	else
+		PG_RETURN_NULL();
+}
+
+/*
+ * regroleout		- converts role OID to "role_name"
+ */
+Datum
+regroleout(PG_FUNCTION_ARGS)
+{
+	Oid			roleoid = PG_GETARG_OID(0);
+	char	   *result;
+
+
+	if (roleoid == InvalidOid)
+	{
+		result = pstrdup("-");
+		PG_RETURN_CSTRING(result);
+	}
+
+	result = GetUserNameFromId(roleoid, true);
+	if (!result)
+	{
+		/* If OID doesn't match any role, return it numerically */
+		result = (char *) palloc(NAMEDATALEN);
+		snprintf(result, NAMEDATALEN, "%u", roleoid);
+	}
+	PG_RETURN_CSTRING(result);
+}
+
+/*
+ *		regrolerecv	- converts external binary format to regrole
+ */
+Datum
+regrolerecv(PG_FUNCTION_ARGS)
+{
+	/* Exactly the same as oidrecv, so share code */
+	return oidrecv(fcinfo);
+}
+
+/*
+ *		regrolesend	- converts regrole to binary format
+ */
+Datum
+regrolesend(PG_FUNCTION_ARGS)
+{
+	/* Exactly the same as oidsend, so share code */
+	return oidsend(fcinfo);
+}
+
+
 
 /*
  * text_regclass: convert text to regclass

src/backend/utils/adt/selfuncs.c

@@ -3619,6 +3619,7 @@ convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue,
 		case REGTYPEOID:
 		case REGCONFIGOID:
 		case REGDICTIONARYOID:
+		case REGROLEOID:
 			*scaledvalue = convert_numeric_to_scalar(value, valuetypid);
 			*scaledlobound = convert_numeric_to_scalar(lobound, boundstypid);
 			*scaledhibound = convert_numeric_to_scalar(hibound, boundstypid);
@@ -3724,6 +3725,7 @@ convert_numeric_to_scalar(Datum value, Oid typid)
 		case REGTYPEOID:
 		case REGCONFIGOID:
 		case REGDICTIONARYOID:
+		case REGROLEOID:
 			/* we can treat OIDs as integers... */
 			return (double) DatumGetObjectId(value);
 	}

src/backend/utils/cache/catcache.c

@@ -150,6 +150,7 @@ GetCCHashEqFuncs(Oid keytype, PGFunction *hashfunc, RegProcedure *eqfunc)
 		case REGTYPEOID:
 		case REGCONFIGOID:
 		case REGDICTIONARYOID:
+		case REGROLEOID:
 			*hashfunc = hashoid;
 
 			*eqfunc = F_OIDEQ;

src/backend/utils/init/miscinit.c

@@ -648,23 +648,29 @@ SetCurrentRoleId(Oid roleid, bool is_superuser)
 
 
 /*
- * Get user name from user oid
+ * Get user name from user oid, returns NULL for nonexistent roleid if noerr
+ * is true.
  */
 char *
-GetUserNameFromId(Oid roleid)
+GetUserNameFromId(Oid roleid, bool noerr)
 {
 	HeapTuple	tuple;
 	char	   *result;
 
 	tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
 	if (!HeapTupleIsValid(tuple))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("invalid role OID: %u", roleid)));
-
-	result = pstrdup(NameStr(((Form_pg_authid) GETSTRUCT(tuple))->rolname));
-
-	ReleaseSysCache(tuple);
+	{
+		if (!noerr)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("invalid role OID: %u", roleid)));
+		result = NULL;
+	}
+	else
+	{
+		result = pstrdup(NameStr(((Form_pg_authid) GETSTRUCT(tuple))->rolname));
+		ReleaseSysCache(tuple);
+	}
 	return result;
 }