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postgresql/src/include/catalog/dependency.h
Tom Lane 1d92a0c9f7 Redesign the partition dependency mechanism. 
The original setup for dependencies of partitioned objects had
serious problems:

1. It did not verify that a drop cascading to a partition-child object
also cascaded to at least one of the object's partition parents.  Now,
normally a child object would share all its dependencies with one or
another parent (e.g. a child index's opclass dependencies would be shared
with the parent index), so that this oversight is usually harmless.
But if some dependency failed to fit this pattern, the child could be
dropped while all its parents remain, creating a logically broken
situation.  (It's easy to construct artificial cases that break it,
such as attaching an unrelated extension dependency to the child object
and then dropping the extension.  I'm not sure if any less-artificial
cases exist.)

2. Management of partition dependencies during ATTACH/DETACH PARTITION
was complicated and buggy; for example, after detaching a partition
table it was possible to create cases where a formerly-child index
should be dropped and was not, because the correct set of dependencies
had not been reconstructed.

Less seriously, because multiple partition relationships were
represented identically in pg_depend, there was an order-of-traversal
dependency on which partition parent was cited in error messages.
We also had some pre-existing order-of-traversal hazards for error
messages related to internal and extension dependencies.  This is
cosmetic to users but causes testing problems.

To fix #1, add a check at the end of the partition tree traversal
to ensure that at least one partition parent got deleted.  To fix #2,
establish a new policy that partition dependencies are in addition to,
not instead of, a child object's usual dependencies; in this way
ATTACH/DETACH PARTITION need not cope with adding or removing the
usual dependencies.

To fix the cosmetic problem, distinguish between primary and secondary
partition dependency entries in pg_depend, by giving them different
deptypes.  (They behave identically except for having different
priorities for being cited in error messages.)  This means that the
former 'I' dependency type is replaced with new 'P' and 'S' types.

This also fixes a longstanding bug that after handling an internal
dependency by recursing to the owning object, findDependentObjects
did not verify that the current target was now scheduled for deletion,
and did not apply the current recursion level's objflags to it.
Perhaps that should be back-patched; but in the back branches it
would only matter if some concurrent transaction had removed the
internal-linkage pg_depend entry before the recursive call found it,
or the recursive call somehow failed to find it, both of which seem
unlikely.

Catversion bump because the contents of pg_depend change for
partitioning relationships.

Patch HEAD only.  It's annoying that we're not fixing #2 in v11,
but there seems no practical way to do so given that the problem
is exactly a poor choice of what entries to put in pg_depend.
We can't really fix that while staying compatible with what's
in pg_depend in existing v11 installations.

Discussion: https://postgr.es/m/CAH2-Wzkypv1R+teZrr71U23J578NnTBt2X8+Y=Odr4pOdW1rXg@mail.gmail.com
2019-02-11 14:41:17 -05:00

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/*-------------------------------------------------------------------------
*
* dependency.h
* Routines to support inter-object dependencies.
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/catalog/dependency.h
*
*-------------------------------------------------------------------------
*/
#ifndef DEPENDENCY_H
#define DEPENDENCY_H
#include "catalog/objectaddress.h"
/*
* 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; see the description of pg_depend
* in catalogs.sgml for details.
*/
typedef enum DependencyType
{
DEPENDENCY_NORMAL = 'n',
DEPENDENCY_AUTO = 'a',
DEPENDENCY_INTERNAL = 'i',
DEPENDENCY_PARTITION_PRI = 'P',
DEPENDENCY_PARTITION_SEC = 'S',
DEPENDENCY_EXTENSION = 'e',
DEPENDENCY_AUTO_EXTENSION = 'x',
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.)
*
* (d) a SHARED_DEPENDENCY_POLICY entry means that the referenced object is
* a role mentioned in a policy object. The referenced object must be a
* pg_authid entry.
*
* 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_POLICY = 'r',
SHARED_DEPENDENCY_INVALID = 0
} SharedDependencyType;
/* expansible list of ObjectAddresses (private in dependency.c) */
typedef struct ObjectAddresses ObjectAddresses;
/*
* This enum covers all system catalogs whose OIDs can appear in
* pg_depend.classId or pg_shdepend.classId. Keep object_classes[] in sync.
*/
typedef enum ObjectClass
{
OCLASS_CLASS, /* pg_class */
OCLASS_PROC, /* pg_proc */
OCLASS_TYPE, /* pg_type */
OCLASS_CAST, /* pg_cast */
OCLASS_COLLATION, /* pg_collation */
OCLASS_CONSTRAINT, /* pg_constraint */
OCLASS_CONVERSION, /* pg_conversion */
OCLASS_DEFAULT, /* pg_attrdef */
OCLASS_LANGUAGE, /* pg_language */
OCLASS_LARGEOBJECT, /* pg_largeobject */
OCLASS_OPERATOR, /* pg_operator */
OCLASS_OPCLASS, /* pg_opclass */
OCLASS_OPFAMILY, /* pg_opfamily */
OCLASS_AM, /* pg_am */
OCLASS_AMOP, /* pg_amop */
OCLASS_AMPROC, /* pg_amproc */
OCLASS_REWRITE, /* pg_rewrite */
OCLASS_TRIGGER, /* pg_trigger */
OCLASS_SCHEMA, /* pg_namespace */
OCLASS_STATISTIC_EXT, /* pg_statistic_ext */
OCLASS_TSPARSER, /* pg_ts_parser */
OCLASS_TSDICT, /* pg_ts_dict */
OCLASS_TSTEMPLATE, /* pg_ts_template */
OCLASS_TSCONFIG, /* pg_ts_config */
OCLASS_ROLE, /* pg_authid */
OCLASS_DATABASE, /* pg_database */
OCLASS_TBLSPACE, /* pg_tablespace */
OCLASS_FDW, /* pg_foreign_data_wrapper */
OCLASS_FOREIGN_SERVER, /* pg_foreign_server */
OCLASS_USER_MAPPING, /* pg_user_mapping */
OCLASS_DEFACL, /* pg_default_acl */
OCLASS_EXTENSION, /* pg_extension */
OCLASS_EVENT_TRIGGER, /* pg_event_trigger */
OCLASS_POLICY, /* pg_policy */
OCLASS_PUBLICATION, /* pg_publication */
OCLASS_PUBLICATION_REL, /* pg_publication_rel */
OCLASS_SUBSCRIPTION, /* pg_subscription */
OCLASS_TRANSFORM /* pg_transform */
} ObjectClass;
#define LAST_OCLASS OCLASS_TRANSFORM
/* flag bits for performDeletion/performMultipleDeletions: */
#define PERFORM_DELETION_INTERNAL 0x0001 /* internal action */
#define PERFORM_DELETION_CONCURRENTLY 0x0002 /* concurrent drop */
#define PERFORM_DELETION_QUIETLY 0x0004 /* suppress notices */
#define PERFORM_DELETION_SKIP_ORIGINAL 0x0008 /* keep original obj */
#define PERFORM_DELETION_SKIP_EXTENSIONS 0x0010 /* keep extensions */
/* in dependency.c */
extern void performDeletion(const ObjectAddress *object,
DropBehavior behavior, int flags);
extern void performMultipleDeletions(const ObjectAddresses *objects,
DropBehavior behavior, int flags);
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,
bool ignore_self);
extern ObjectClass getObjectClass(const ObjectAddress *object);
extern ObjectAddresses *new_object_addresses(void);
extern void add_exact_object_address(const ObjectAddress *object,
ObjectAddresses *addrs);
extern bool object_address_present(const ObjectAddress *object,
const ObjectAddresses *addrs);
extern void record_object_address_dependencies(const ObjectAddress *depender,
ObjectAddresses *referenced,
DependencyType behavior);
extern void free_object_addresses(ObjectAddresses *addrs);
/* 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 void recordDependencyOnCurrentExtension(const ObjectAddress *object,
bool isReplace);
extern long deleteDependencyRecordsFor(Oid classId, Oid objectId,
bool skipExtensionDeps);
extern long deleteDependencyRecordsForClass(Oid classId, Oid objectId,
Oid refclassId, char deptype);
extern long changeDependencyFor(Oid classId, Oid objectId,
Oid refClassId, Oid oldRefObjectId,
Oid newRefObjectId);
extern Oid getExtensionOfObject(Oid classId, Oid objectId);
extern bool sequenceIsOwned(Oid seqId, char deptype, Oid *tableId, int32 *colId);
extern List *getOwnedSequences(Oid relid, AttrNumber attnum);
extern Oid getOwnedSequence(Oid relid, AttrNumber attnum);
extern Oid get_constraint_index(Oid constraintId);
extern Oid get_index_constraint(Oid indexId);
/* in pg_shdepend.c */
extern void recordSharedDependencyOn(ObjectAddress *depender,
ObjectAddress *referenced,
SharedDependencyType deptype);
extern void deleteSharedDependencyRecordsFor(Oid classId, Oid objectId,
int32 objectSubId);
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, int32 objectSubId,
Oid ownerId,
int noldmembers, Oid *oldmembers,
int nnewmembers, Oid *newmembers);
extern bool checkSharedDependencies(Oid classId, Oid objectId,
char **detail_msg, char **detail_log_msg);
extern void shdepLockAndCheckObject(Oid classId, Oid objectId);
extern void copyTemplateDependencies(Oid templateDbId, Oid newDbId);
extern void dropDatabaseDependencies(Oid databaseId);
extern void shdepDropOwned(List *relids, DropBehavior behavior);
extern void shdepReassignOwned(List *relids, Oid newrole);
#endif /* DEPENDENCY_H */
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