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/*-------------------------------------------------------------------------
*
* dependency.h
* Routines to support inter-object dependencies.
*
*
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/catalog/dependency.h,v 1.11 2003/11/29 22:40:58 pgsql 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;
/*
* 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;
/* 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);
/* 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);
#endif /* DEPENDENCY_H */
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