dependency.h

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

/*-------------------------------------------------------------------------
 *
 * dependency.h
 *	  Routines to support inter-object dependencies.
 *
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/catalog/dependency.h,v 1.17 2005/10/15 02:49:42 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef DEPENDENCY_H
#define DEPENDENCY_H

#include "nodes/parsenodes.h"	/* for DropBehavior */


/*----------
 * Precise semantics of a dependency relationship are specified by the
 * DependencyType code (which is stored in a "char" field in pg_depend,
 * so we assign ASCII-code values to the enumeration members).
 *
 * In all cases, a dependency relationship indicates that the referenced
 * object may not be dropped without also dropping the dependent object.
 * However, there are several subflavors:
 *
 * DEPENDENCY_NORMAL ('n'): normal relationship between separately-created
 * objects.  The dependent object may be dropped without affecting the
 * referenced object.  The referenced object may only be dropped by
 * specifying CASCADE, in which case the dependent object is dropped too.
 * Example: a table column has a normal dependency on its datatype.
 *
 * DEPENDENCY_AUTO ('a'): the dependent object can be dropped separately
 * from the referenced object, and should be automatically dropped
 * (regardless of RESTRICT or CASCADE mode) if the referenced object
 * is dropped.
 * Example: a named constraint on a table is made auto-dependent on
 * the table, so that it will go away if the table is dropped.
 *
 * DEPENDENCY_INTERNAL ('i'): the dependent object was created as part
 * of creation of the referenced object, and is really just a part of
 * its internal implementation.  A DROP of the dependent object will be
 * disallowed outright (we'll tell the user to issue a DROP against the
 * referenced object, instead).  A DROP of the referenced object will be
 * propagated through to drop the dependent object whether CASCADE is
 * specified or not.
 * Example: a trigger that's created to enforce a foreign-key constraint
 * is made internally dependent on the constraint's pg_constraint entry.
 *
 * DEPENDENCY_PIN ('p'): there is no dependent object; this type of entry
 * is a signal that the system itself depends on the referenced object,
 * and so that object must never be deleted.  Entries of this type are
 * created only during initdb.	The fields for the dependent object
 * contain zeroes.
 *
 * Other dependency flavors may be needed in future.
 *----------
 */

typedef enum DependencyType
{
	DEPENDENCY_NORMAL = 'n',
	DEPENDENCY_AUTO = 'a',
	DEPENDENCY_INTERNAL = 'i',
	DEPENDENCY_PIN = 'p'
} DependencyType;

/*
 * There is also a SharedDependencyType enum type that determines the exact
 * semantics of an entry in pg_shdepend.  Just like regular dependency entries,
 * any pg_shdepend entry means that the referenced object cannot be dropped
 * unless the dependent object is dropped at the same time.  There are some
 * additional rules however:
 *
 * (a) For a SHARED_DEPENDENCY_PIN entry, there is no dependent object --
 * rather, the referenced object is an essential part of the system.  This
 * applies to the initdb-created superuser.  Entries of this type are only
 * created by initdb; objects in this category don't need further pg_shdepend
 * entries if more objects come to depend on them.
 *
 * (b) a SHARED_DEPENDENCY_OWNER entry means that the referenced object is
 * the role owning the dependent object.  The referenced object must be
 * a pg_authid entry.
 *
 * (c) a SHARED_DEPENDENCY_ACL entry means that the referenced object is
 * a role mentioned in the ACL field of the dependent object.  The referenced
 * object must be a pg_authid entry.  (SHARED_DEPENDENCY_ACL entries are not
 * created for the owner of an object; hence two objects may be linked by
 * one or the other, but not both, of these dependency types.)
 *
 * SHARED_DEPENDENCY_INVALID is a value used as a parameter in internal
 * routines, and is not valid in the catalog itself.
 */
typedef enum SharedDependencyType
{
	SHARED_DEPENDENCY_PIN = 'p',
	SHARED_DEPENDENCY_OWNER = 'o',
	SHARED_DEPENDENCY_ACL = 'a',
	SHARED_DEPENDENCY_INVALID = 0
} SharedDependencyType;


/*
 * The two objects related by a dependency are identified by ObjectAddresses.
 */
typedef struct ObjectAddress
{
	Oid			classId;		/* Class Id from pg_class */
	Oid			objectId;		/* OID of the object */
	int32		objectSubId;	/* Subitem within the object (column of table) */
} ObjectAddress;


/*
 * This enum covers all system catalogs whose OIDs can appear in
 * pg_depend.classId or pg_shdepend.classId.
 */
typedef enum ObjectClass
{
	OCLASS_CLASS,				/* pg_class */
	OCLASS_PROC,				/* pg_proc */
	OCLASS_TYPE,				/* pg_type */
	OCLASS_CAST,				/* pg_cast */
	OCLASS_CONSTRAINT,			/* pg_constraint */
	OCLASS_CONVERSION,			/* pg_conversion */
	OCLASS_DEFAULT,				/* pg_attrdef */
	OCLASS_LANGUAGE,			/* pg_language */
	OCLASS_OPERATOR,			/* pg_operator */
	OCLASS_OPCLASS,				/* pg_opclass */
	OCLASS_REWRITE,				/* pg_rewrite */
	OCLASS_TRIGGER,				/* pg_trigger */
	OCLASS_SCHEMA,				/* pg_namespace */
	OCLASS_ROLE,				/* pg_authid */
	OCLASS_DATABASE,			/* pg_database */
	OCLASS_TBLSPACE,			/* pg_tablespace */
	MAX_OCLASS					/* MUST BE LAST */
} ObjectClass;


/* in dependency.c */

extern void performDeletion(const ObjectAddress *object,
				DropBehavior behavior);

extern void deleteWhatDependsOn(const ObjectAddress *object,
					bool showNotices);

extern void recordDependencyOnExpr(const ObjectAddress *depender,
					   Node *expr, List *rtable,
					   DependencyType behavior);

extern void recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
								Node *expr, Oid relId,
								DependencyType behavior,
								DependencyType self_behavior);

extern ObjectClass getObjectClass(const ObjectAddress *object);

extern char *getObjectDescription(const ObjectAddress *object);

/* in pg_depend.c */

extern void recordDependencyOn(const ObjectAddress *depender,
				   const ObjectAddress *referenced,
				   DependencyType behavior);

extern void recordMultipleDependencies(const ObjectAddress *depender,
						   const ObjectAddress *referenced,
						   int nreferenced,
						   DependencyType behavior);

extern long deleteDependencyRecordsFor(Oid classId, Oid objectId);

extern long changeDependencyFor(Oid classId, Oid objectId,
					Oid refClassId, Oid oldRefObjectId,
					Oid newRefObjectId);

/* in pg_shdepend.c */

extern void recordSharedDependencyOn(ObjectAddress *depender,
						 ObjectAddress *referenced,
						 SharedDependencyType deptype);

extern void deleteSharedDependencyRecordsFor(Oid classId, Oid objectId);

extern void recordDependencyOnOwner(Oid classId, Oid objectId, Oid owner);

extern void changeDependencyOnOwner(Oid classId, Oid objectId,
						Oid newOwnerId);

extern void updateAclDependencies(Oid classId, Oid objectId,
					  Oid ownerId, bool isGrant,
					  int noldmembers, Oid *oldmembers,
					  int nnewmembers, Oid *newmembers);

extern char *checkSharedDependencies(Oid classId, Oid objectId);

extern void copyTemplateDependencies(Oid templateDbId, Oid newDbId);

extern void dropDatabaseDependencies(Oid databaseId);

#endif   /* DEPENDENCY_H */