Remove ObjectClass type

ObjectClass is an enum whose values correspond to catalog OIDs.  But
the extra layer of redirection, which is used only in small parts of
the code, and the similarity to ObjectType, are confusing and
cumbersome.

One advantage has been that some switches processing the OCLASS enum
don't have "default:" cases.  This is so that the compiler tells us
when we fail to add support for some new object class.  But you can
also handle that with some assertions and proper test coverage.  It's
not even clear how strong this benefit is.  For example, in
AlterObjectNamespace_oid(), you could still put a new OCLASS into the
"ignore object types that don't have schema-qualified names" case, and
it might or might not be wrong.  Also, there are already various
OCLASS switches that do have a default case, so it's not even clear
what the preferred coding style should be.

Reviewed-by: jian he <jian.universality@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://www.postgresql.org/message-id/flat/CAGECzQT3caUbcCcszNewCCmMbCuyP7XNAm60J3ybd6PN5kH2Dw%40mail.gmail.com

Author: petere

src/backend/catalog/dependency.c

@@ -206,7 +206,7 @@ deleteObjectsInList(ObjectAddresses *targetObjects, Relation *depRel,
 			if (extra->flags & DEPFLAG_REVERSE)
 				normal = true;
 
-			if (EventTriggerSupportsObjectClass(getObjectClass(thisobj)))
+			if (EventTriggerSupportsObject(thisobj))
 			{
 				EventTriggerSQLDropAddObject(thisobj, original, normal);
 			}
@@ -1349,9 +1349,9 @@ deleteOneObject(const ObjectAddress *object, Relation *depRel, int flags)
 static void
 doDeletion(const ObjectAddress *object, int flags)
 {
-	switch (getObjectClass(object))
+	switch (object->classId)
 	{
-		case OCLASS_CLASS:
+		case RelationRelationId:
 			{
 				char		relKind = get_rel_relkind(object->objectId);
 
@@ -1382,104 +1382,102 @@ doDeletion(const ObjectAddress *object, int flags)
 				break;
 			}
 
-		case OCLASS_PROC:
+		case ProcedureRelationId:
 			RemoveFunctionById(object->objectId);
 			break;
 
-		case OCLASS_TYPE:
+		case TypeRelationId:
 			RemoveTypeById(object->objectId);
 			break;
 
-		case OCLASS_CONSTRAINT:
+		case ConstraintRelationId:
 			RemoveConstraintById(object->objectId);
 			break;
 
-		case OCLASS_DEFAULT:
+		case AttrDefaultRelationId:
 			RemoveAttrDefaultById(object->objectId);
 			break;
 
-		case OCLASS_LARGEOBJECT:
+		case LargeObjectRelationId:
 			LargeObjectDrop(object->objectId);
 			break;
 
-		case OCLASS_OPERATOR:
+		case OperatorRelationId:
 			RemoveOperatorById(object->objectId);
 			break;
 
-		case OCLASS_REWRITE:
+		case RewriteRelationId:
 			RemoveRewriteRuleById(object->objectId);
 			break;
 
-		case OCLASS_TRIGGER:
+		case TriggerRelationId:
 			RemoveTriggerById(object->objectId);
 			break;
 
-		case OCLASS_STATISTIC_EXT:
+		case StatisticExtRelationId:
 			RemoveStatisticsById(object->objectId);
 			break;
 
-		case OCLASS_TSCONFIG:
+		case TSConfigRelationId:
 			RemoveTSConfigurationById(object->objectId);
 			break;
 
-		case OCLASS_EXTENSION:
+		case ExtensionRelationId:
 			RemoveExtensionById(object->objectId);
 			break;
 
-		case OCLASS_POLICY:
+		case PolicyRelationId:
 			RemovePolicyById(object->objectId);
 			break;
 
-		case OCLASS_PUBLICATION_NAMESPACE:
+		case PublicationNamespaceRelationId:
 			RemovePublicationSchemaById(object->objectId);
 			break;
 
-		case OCLASS_PUBLICATION_REL:
+		case PublicationRelRelationId:
 			RemovePublicationRelById(object->objectId);
 			break;
 
-		case OCLASS_PUBLICATION:
+		case PublicationRelationId:
 			RemovePublicationById(object->objectId);
 			break;
 
-		case OCLASS_CAST:
-		case OCLASS_COLLATION:
-		case OCLASS_CONVERSION:
-		case OCLASS_LANGUAGE:
-		case OCLASS_OPCLASS:
-		case OCLASS_OPFAMILY:
-		case OCLASS_AM:
-		case OCLASS_AMOP:
-		case OCLASS_AMPROC:
-		case OCLASS_SCHEMA:
-		case OCLASS_TSPARSER:
-		case OCLASS_TSDICT:
-		case OCLASS_TSTEMPLATE:
-		case OCLASS_FDW:
-		case OCLASS_FOREIGN_SERVER:
-		case OCLASS_USER_MAPPING:
-		case OCLASS_DEFACL:
-		case OCLASS_EVENT_TRIGGER:
-		case OCLASS_TRANSFORM:
-		case OCLASS_ROLE_MEMBERSHIP:
+		case CastRelationId:
+		case CollationRelationId:
+		case ConversionRelationId:
+		case LanguageRelationId:
+		case OperatorClassRelationId:
+		case OperatorFamilyRelationId:
+		case AccessMethodRelationId:
+		case AccessMethodOperatorRelationId:
+		case AccessMethodProcedureRelationId:
+		case NamespaceRelationId:
+		case TSParserRelationId:
+		case TSDictionaryRelationId:
+		case TSTemplateRelationId:
+		case ForeignDataWrapperRelationId:
+		case ForeignServerRelationId:
+		case UserMappingRelationId:
+		case DefaultAclRelationId:
+		case EventTriggerRelationId:
+		case TransformRelationId:
+		case AuthMemRelationId:
 			DropObjectById(object);
 			break;
 
 			/*
 			 * These global object types are not supported here.
 			 */
-		case OCLASS_ROLE:
-		case OCLASS_DATABASE:
-		case OCLASS_TBLSPACE:
-		case OCLASS_SUBSCRIPTION:
-		case OCLASS_PARAMETER_ACL:
+		case AuthIdRelationId:
+		case DatabaseRelationId:
+		case TableSpaceRelationId:
+		case SubscriptionRelationId:
+		case ParameterAclRelationId:
 			elog(ERROR, "global objects cannot be deleted by doDeletion");
 			break;
 
-			/*
-			 * There's intentionally no default: case here; we want the
-			 * compiler to warn if a new OCLASS hasn't been handled above.
-			 */
+		default:
+			elog(ERROR, "unsupported object class: %u", object->classId);
 	}
 }
 
@@ -2774,153 +2772,6 @@ free_object_addresses(ObjectAddresses *addrs)
 	pfree(addrs);
 }
 
-/*
- * Determine the class of a given object identified by objectAddress.
- *
- * We implement it as a function instead of an array because the OIDs aren't
- * consecutive.
- */
-ObjectClass
-getObjectClass(const ObjectAddress *object)
-{
-	/* only pg_class entries can have nonzero objectSubId */
-	if (object->classId != RelationRelationId &&
-		object->objectSubId != 0)
-		elog(ERROR, "invalid non-zero objectSubId for object class %u",
-			 object->classId);
-
-	switch (object->classId)
-	{
-		case RelationRelationId:
-			/* caller must check objectSubId */
-			return OCLASS_CLASS;
-
-		case ProcedureRelationId:
-			return OCLASS_PROC;
-
-		case TypeRelationId:
-			return OCLASS_TYPE;
-
-		case CastRelationId:
-			return OCLASS_CAST;
-
-		case CollationRelationId:
-			return OCLASS_COLLATION;
-
-		case ConstraintRelationId:
-			return OCLASS_CONSTRAINT;
-
-		case ConversionRelationId:
-			return OCLASS_CONVERSION;
-
-		case AttrDefaultRelationId:
-			return OCLASS_DEFAULT;
-
-		case LanguageRelationId:
-			return OCLASS_LANGUAGE;
-
-		case LargeObjectRelationId:
-			return OCLASS_LARGEOBJECT;
-
-		case OperatorRelationId:
-			return OCLASS_OPERATOR;
-
-		case OperatorClassRelationId:
-			return OCLASS_OPCLASS;
-
-		case OperatorFamilyRelationId:
-			return OCLASS_OPFAMILY;
-
-		case AccessMethodRelationId:
-			return OCLASS_AM;
-
-		case AccessMethodOperatorRelationId:
-			return OCLASS_AMOP;
-
-		case AccessMethodProcedureRelationId:
-			return OCLASS_AMPROC;
-
-		case RewriteRelationId:
-			return OCLASS_REWRITE;
-
-		case TriggerRelationId:
-			return OCLASS_TRIGGER;
-
-		case NamespaceRelationId:
-			return OCLASS_SCHEMA;
-
-		case StatisticExtRelationId:
-			return OCLASS_STATISTIC_EXT;
-
-		case TSParserRelationId:
-			return OCLASS_TSPARSER;
-
-		case TSDictionaryRelationId:
-			return OCLASS_TSDICT;
-
-		case TSTemplateRelationId:
-			return OCLASS_TSTEMPLATE;
-
-		case TSConfigRelationId:
-			return OCLASS_TSCONFIG;
-
-		case AuthIdRelationId:
-			return OCLASS_ROLE;
-
-		case AuthMemRelationId:
-			return OCLASS_ROLE_MEMBERSHIP;
-
-		case DatabaseRelationId:
-			return OCLASS_DATABASE;
-
-		case TableSpaceRelationId:
-			return OCLASS_TBLSPACE;
-
-		case ForeignDataWrapperRelationId:
-			return OCLASS_FDW;
-
-		case ForeignServerRelationId:
-			return OCLASS_FOREIGN_SERVER;
-
-		case UserMappingRelationId:
-			return OCLASS_USER_MAPPING;
-
-		case DefaultAclRelationId:
-			return OCLASS_DEFACL;
-
-		case ExtensionRelationId:
-			return OCLASS_EXTENSION;
-
-		case EventTriggerRelationId:
-			return OCLASS_EVENT_TRIGGER;
-
-		case ParameterAclRelationId:
-			return OCLASS_PARAMETER_ACL;
-
-		case PolicyRelationId:
-			return OCLASS_POLICY;
-
-		case PublicationNamespaceRelationId:
-			return OCLASS_PUBLICATION_NAMESPACE;
-
-		case PublicationRelationId:
-			return OCLASS_PUBLICATION;
-
-		case PublicationRelRelationId:
-			return OCLASS_PUBLICATION_REL;
-
-		case SubscriptionRelationId:
-			return OCLASS_SUBSCRIPTION;
-
-		case TransformRelationId:
-			return OCLASS_TRANSFORM;
-	}
-
-	/* shouldn't get here */
-	elog(ERROR, "unrecognized object class: %u", object->classId);
-	return OCLASS_CLASS;		/* keep compiler quiet */
-}
-
 /*
  * delete initial ACL for extension objects
  */