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113 lines
3.9 KiB
C
113 lines
3.9 KiB
C
/*-------------------------------------------------------------------------
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*
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* dependency.h
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* Routines to support inter-object dependencies.
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*
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*
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* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: dependency.h,v 1.10 2003/08/04 02:40:10 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef DEPENDENCY_H
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#define DEPENDENCY_H
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#include "nodes/parsenodes.h" /* for DropBehavior */
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/*
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* Precise semantics of a dependency relationship are specified by the
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* DependencyType code (which is stored in a "char" field in pg_depend,
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* so we assign ASCII-code values to the enumeration members).
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*
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* In all cases, a dependency relationship indicates that the referenced
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* object may not be dropped without also dropping the dependent object.
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* However, there are several subflavors:
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*
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* DEPENDENCY_NORMAL ('n'): normal relationship between separately-created
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* objects. The dependent object may be dropped without affecting the
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* referenced object. The referenced object may only be dropped by
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* specifying CASCADE, in which case the dependent object is dropped too.
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* Example: a table column has a normal dependency on its datatype.
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*
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* DEPENDENCY_AUTO ('a'): the dependent object can be dropped separately
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* from the referenced object, and should be automatically dropped
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* (regardless of RESTRICT or CASCADE mode) if the referenced object
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* is dropped.
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* Example: a named constraint on a table is made auto-dependent on
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* the table, so that it will go away if the table is dropped.
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*
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* DEPENDENCY_INTERNAL ('i'): the dependent object was created as part
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* of creation of the referenced object, and is really just a part of
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* its internal implementation. A DROP of the dependent object will be
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* disallowed outright (we'll tell the user to issue a DROP against the
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* referenced object, instead). A DROP of the referenced object will be
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* propagated through to drop the dependent object whether CASCADE is
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* specified or not.
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* Example: a trigger that's created to enforce a foreign-key constraint
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* is made internally dependent on the constraint's pg_constraint entry.
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*
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* DEPENDENCY_PIN ('p'): there is no dependent object; this type of entry
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* is a signal that the system itself depends on the referenced object,
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* and so that object must never be deleted. Entries of this type are
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* created only during initdb. The fields for the dependent object
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* contain zeroes.
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*
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* Other dependency flavors may be needed in future.
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*/
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typedef enum DependencyType
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{
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DEPENDENCY_NORMAL = 'n',
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DEPENDENCY_AUTO = 'a',
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DEPENDENCY_INTERNAL = 'i',
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DEPENDENCY_PIN = 'p'
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} DependencyType;
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/*
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* The two objects related by a dependency are identified by ObjectAddresses.
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*/
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typedef struct ObjectAddress
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{
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Oid classId; /* Class Id from pg_class */
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Oid objectId; /* OID of the object */
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int32 objectSubId; /* Subitem within the object (column of
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* table) */
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} ObjectAddress;
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/* in dependency.c */
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extern void performDeletion(const ObjectAddress *object,
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DropBehavior behavior);
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extern void deleteWhatDependsOn(const ObjectAddress *object,
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bool showNotices);
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extern void recordDependencyOnExpr(const ObjectAddress *depender,
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Node *expr, List *rtable,
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DependencyType behavior);
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extern void recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
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Node *expr, Oid relId,
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DependencyType behavior,
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DependencyType self_behavior);
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/* in pg_depend.c */
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extern void recordDependencyOn(const ObjectAddress *depender,
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const ObjectAddress *referenced,
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DependencyType behavior);
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extern void recordMultipleDependencies(const ObjectAddress *depender,
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const ObjectAddress *referenced,
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int nreferenced,
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DependencyType behavior);
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extern long deleteDependencyRecordsFor(Oid classId, Oid objectId);
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#endif /* DEPENDENCY_H */
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