heap.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

				/*
				 * Unneeded since they should be OK in the constant data
				 * anyway
				 */
				/* attStruct->attstattarget = 0; */
				/* attStruct->attcacheoff = -1; */

				simple_heap_insert(rel, tup);

				CatalogIndexInsert(indstate, tup);

				heap_freetuple(tup);
			}
			dpp++;
		}
	}

	/*
	 * clean up
	 */
	CatalogCloseIndexes(indstate);

	heap_close(rel, RowExclusiveLock);
}

/* --------------------------------
 *		AddNewRelationTuple
 *
 *		this registers the new relation in the catalogs by
 *		adding a tuple to pg_class.
 * --------------------------------
 */
static void
AddNewRelationTuple(Relation pg_class_desc,
					Relation new_rel_desc,
					Oid new_rel_oid,
					Oid new_type_oid,
					Oid relowner,
					char relkind)
{
	Form_pg_class new_rel_reltup;
	HeapTuple	tup;

	/*
	 * first we update some of the information in our uncataloged relation's
	 * relation descriptor.
	 */
	new_rel_reltup = new_rel_desc->rd_rel;

	switch (relkind)
	{
		case RELKIND_RELATION:
		case RELKIND_INDEX:
		case RELKIND_TOASTVALUE:
			/* The relation is real, but as yet empty */
			new_rel_reltup->relpages = 0;
			new_rel_reltup->reltuples = 0;
			break;
		case RELKIND_SEQUENCE:
			/* Sequences always have a known size */
			new_rel_reltup->relpages = 1;
			new_rel_reltup->reltuples = 1;
			break;
		default:
			/* Views, etc, have no disk storage */
			new_rel_reltup->relpages = 0;
			new_rel_reltup->reltuples = 0;
			break;
	}

	new_rel_reltup->relowner = relowner;
	new_rel_reltup->reltype = new_type_oid;
	new_rel_reltup->relkind = relkind;

	new_rel_desc->rd_att->tdtypeid = new_type_oid;

	/* ----------------
	 *	now form a tuple to add to pg_class
	 *	XXX Natts_pg_class_fixed is a hack - see pg_class.h
	 * ----------------
	 */
	tup = heap_addheader(Natts_pg_class_fixed,
						 true,
						 CLASS_TUPLE_SIZE,
						 (void *) new_rel_reltup);

	/* force tuple to have the desired OID */
	HeapTupleSetOid(tup, new_rel_oid);

	/*
	 * finally insert the new tuple, update the indexes, and clean up.
	 */
	simple_heap_insert(pg_class_desc, tup);

	CatalogUpdateIndexes(pg_class_desc, tup);

	heap_freetuple(tup);
}


/* --------------------------------
 *		AddNewRelationType -
 *
 *		define a composite type corresponding to the new relation
 * --------------------------------
 */
static Oid
AddNewRelationType(const char *typeName,
				   Oid typeNamespace,
				   Oid new_rel_oid,
				   char new_rel_kind)
{
	return
		TypeCreate(typeName,	/* type name */
				   typeNamespace,		/* type namespace */
				   new_rel_oid, /* relation oid */
				   new_rel_kind,	/* relation kind */
				   -1,			/* internal size (varlena) */
				   'c',			/* type-type (complex) */
				   ',',			/* default array delimiter */
				   F_RECORD_IN, /* input procedure */
				   F_RECORD_OUT,	/* output procedure */
				   F_RECORD_RECV,		/* receive procedure */
				   F_RECORD_SEND,		/* send procedure */
				   InvalidOid,	/* analyze procedure - default */
				   InvalidOid,	/* array element type - irrelevant */
				   InvalidOid,	/* domain base type - irrelevant */
				   NULL,		/* default value - none */
				   NULL,		/* default binary representation */
				   false,		/* passed by reference */
				   'd',			/* alignment - must be the largest! */
				   'x',			/* fully TOASTable */
				   -1,			/* typmod */
				   0,			/* array dimensions for typBaseType */
				   false);		/* Type NOT NULL */
}

/* --------------------------------
 *		heap_create_with_catalog
 *
 *		creates a new cataloged relation.  see comments above.
 * --------------------------------
 */
Oid
heap_create_with_catalog(const char *relname,
						 Oid relnamespace,
						 Oid reltablespace,
						 Oid relid,
						 Oid ownerid,
						 TupleDesc tupdesc,
						 char relkind,
						 bool shared_relation,
						 bool oidislocal,
						 int oidinhcount,
						 OnCommitAction oncommit,
						 bool allow_system_table_mods)
{
	Relation	pg_class_desc;
	Relation	new_rel_desc;
	Oid			new_type_oid;

	pg_class_desc = heap_open(RelationRelationId, RowExclusiveLock);

	/*
	 * sanity checks
	 */
	Assert(IsNormalProcessingMode() || IsBootstrapProcessingMode());

	CheckAttributeNamesTypes(tupdesc, relkind);

	if (get_relname_relid(relname, relnamespace))
		ereport(ERROR,
				(errcode(ERRCODE_DUPLICATE_TABLE),
				 errmsg("relation \"%s\" already exists", relname)));

	/*
	 * Allocate an OID for the relation, unless we were told what to use.
	 *
	 * The OID will be the relfilenode as well, so make sure it doesn't
	 * collide with either pg_class OIDs or existing physical files.
	 */
	if (!OidIsValid(relid))
		relid = GetNewRelFileNode(reltablespace, shared_relation,
								  pg_class_desc);

	/*
	 * Create the relcache entry (mostly dummy at this point) and the physical
	 * disk file.  (If we fail further down, it's the smgr's responsibility to
	 * remove the disk file again.)
	 */
	new_rel_desc = heap_create(relname,
							   relnamespace,
							   reltablespace,
							   relid,
							   tupdesc,
							   relkind,
							   shared_relation,
							   allow_system_table_mods);

	Assert(relid == RelationGetRelid(new_rel_desc));

	/*
	 * since defining a relation also defines a complex type, we add a new
	 * system type corresponding to the new relation.
	 *
	 * NOTE: we could get a unique-index failure here, in case the same name
	 * has already been used for a type.
	 */
	new_type_oid = AddNewRelationType(relname,
									  relnamespace,
									  relid,
									  relkind);

	/*
	 * now create an entry in pg_class for the relation.
	 *
	 * NOTE: we could get a unique-index failure here, in case someone else is
	 * creating the same relation name in parallel but hadn't committed yet
	 * when we checked for a duplicate name above.
	 */
	AddNewRelationTuple(pg_class_desc,
						new_rel_desc,
						relid,
						new_type_oid,
						ownerid,
						relkind);

	/*
	 * now add tuples to pg_attribute for the attributes in our new relation.
	 */
	AddNewAttributeTuples(relid, new_rel_desc->rd_att, relkind,
						  oidislocal, oidinhcount);

	/*
	 * make a dependency link to force the relation to be deleted if its
	 * namespace is.  Skip this in bootstrap mode, since we don't make
	 * dependencies while bootstrapping.
	 *
	 * Also make a dependency link to its owner.
	 */
	if (!IsBootstrapProcessingMode())
	{
		ObjectAddress myself,
					referenced;

		myself.classId = RelationRelationId;
		myself.objectId = relid;
		myself.objectSubId = 0;
		referenced.classId = NamespaceRelationId;
		referenced.objectId = relnamespace;
		referenced.objectSubId = 0;
		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

		/*
		 * For composite types, the dependency on owner is tracked for the
		 * pg_type entry, so don't record it here.  All other relkinds need
		 * their ownership tracked.
		 */
		if (relkind != RELKIND_COMPOSITE_TYPE)
			recordDependencyOnOwner(RelationRelationId, relid, ownerid);
	}

	/*
	 * store constraints and defaults passed in the tupdesc, if any.
	 *
	 * NB: this may do a CommandCounterIncrement and rebuild the relcache
	 * entry, so the relation must be valid and self-consistent at this point.
	 * In particular, there are not yet constraints and defaults anywhere.
	 */
	StoreConstraints(new_rel_desc, tupdesc);

	/*
	 * If there's a special on-commit action, remember it
	 */
	if (oncommit != ONCOMMIT_NOOP)
		register_on_commit_action(relid, oncommit);

	/*
	 * ok, the relation has been cataloged, so close our relations and return
	 * the OID of the newly created relation.
	 */
	heap_close(new_rel_desc, NoLock);	/* do not unlock till end of xact */
	heap_close(pg_class_desc, RowExclusiveLock);

	return relid;
}


/*
 *		RelationRemoveInheritance
 *
 * Formerly, this routine checked for child relations and aborted the
 * deletion if any were found.	Now we rely on the dependency mechanism
 * to check for or delete child relations.	By the time we get here,
 * there are no children and we need only remove any pg_inherits rows
 * linking this relation to its parent(s).
 */
static void
RelationRemoveInheritance(Oid relid)
{
	Relation	catalogRelation;
	SysScanDesc scan;
	ScanKeyData key;
	HeapTuple	tuple;

	catalogRelation = heap_open(InheritsRelationId, RowExclusiveLock);

	ScanKeyInit(&key,
				Anum_pg_inherits_inhrelid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(relid));

	scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId, true,
							  SnapshotNow, 1, &key);

	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
		simple_heap_delete(catalogRelation, &tuple->t_self);

	systable_endscan(scan);
	heap_close(catalogRelation, RowExclusiveLock);
}

/*
 *		DeleteRelationTuple
 *
 * Remove pg_class row for the given relid.
 *
 * Note: this is shared by relation deletion and index deletion.  It's
 * not intended for use anyplace else.
 */
void
DeleteRelationTuple(Oid relid)
{
	Relation	pg_class_desc;
	HeapTuple	tup;

	/* Grab an appropriate lock on the pg_class relation */
	pg_class_desc = heap_open(RelationRelationId, RowExclusiveLock);

	tup = SearchSysCache(RELOID,
						 ObjectIdGetDatum(relid),
						 0, 0, 0);
	if (!HeapTupleIsValid(tup))
		elog(ERROR, "cache lookup failed for relation %u", relid);

	/* delete the relation tuple from pg_class, and finish up */
	simple_heap_delete(pg_class_desc, &tup->t_self);

	ReleaseSysCache(tup);

	heap_close(pg_class_desc, RowExclusiveLock);
}

/*
 *		DeleteAttributeTuples
 *
 * Remove pg_attribute rows for the given relid.
 *
 * Note: this is shared by relation deletion and index deletion.  It's
 * not intended for use anyplace else.
 */
void
DeleteAttributeTuples(Oid relid)
{
	Relation	attrel;
	SysScanDesc scan;
	ScanKeyData key[1];
	HeapTuple	atttup;

	/* Grab an appropriate lock on the pg_attribute relation */
	attrel = heap_open(AttributeRelationId, RowExclusiveLock);

	/* Use the index to scan only attributes of the target relation */
	ScanKeyInit(&key[0],
				Anum_pg_attribute_attrelid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(relid));

	scan = systable_beginscan(attrel, AttributeRelidNumIndexId, true,
							  SnapshotNow, 1, key);

	/* Delete all the matching tuples */
	while ((atttup = systable_getnext(scan)) != NULL)
		simple_heap_delete(attrel, &atttup->t_self);

	/* Clean up after the scan */
	systable_endscan(scan);
	heap_close(attrel, RowExclusiveLock);
}

/*
 *		RemoveAttributeById
 *
 * This is the guts of ALTER TABLE DROP COLUMN: actually mark the attribute
 * deleted in pg_attribute.  We also remove pg_statistic entries for it.
 * (Everything else needed, such as getting rid of any pg_attrdef entry,
 * is handled by dependency.c.)
 */
void
RemoveAttributeById(Oid relid, AttrNumber attnum)
{
	Relation	rel;
	Relation	attr_rel;
	HeapTuple	tuple;
	Form_pg_attribute attStruct;
	char		newattname[NAMEDATALEN];

	/*
	 * Grab an exclusive lock on the target table, which we will NOT release
	 * until end of transaction.  (In the simple case where we are directly
	 * dropping this column, AlterTableDropColumn already did this ... but
	 * when cascading from a drop of some other object, we may not have any
	 * lock.)
	 */
	rel = relation_open(relid, AccessExclusiveLock);

	attr_rel = heap_open(AttributeRelationId, RowExclusiveLock);

	tuple = SearchSysCacheCopy(ATTNUM,
							   ObjectIdGetDatum(relid),
							   Int16GetDatum(attnum),
							   0, 0);
	if (!HeapTupleIsValid(tuple))		/* shouldn't happen */
		elog(ERROR, "cache lookup failed for attribute %d of relation %u",
			 attnum, relid);
	attStruct = (Form_pg_attribute) GETSTRUCT(tuple);

	if (attnum < 0)
	{
		/* System attribute (probably OID) ... just delete the row */

		simple_heap_delete(attr_rel, &tuple->t_self);
	}
	else
	{
		/* Dropping user attributes is lots harder */

		/* Mark the attribute as dropped */
		attStruct->attisdropped = true;

		/*
		 * Set the type OID to invalid.  A dropped attribute's type link
		 * cannot be relied on (once the attribute is dropped, the type might
		 * be too). Fortunately we do not need the type row --- the only
		 * really essential information is the type's typlen and typalign,
		 * which are preserved in the attribute's attlen and attalign.  We set
		 * atttypid to zero here as a means of catching code that incorrectly
		 * expects it to be valid.
		 */
		attStruct->atttypid = InvalidOid;

		/* Remove any NOT NULL constraint the column may have */
		attStruct->attnotnull = false;

		/* We don't want to keep stats for it anymore */
		attStruct->attstattarget = 0;

		/*
		 * Change the column name to something that isn't likely to conflict
		 */
		snprintf(newattname, sizeof(newattname),
				 "........pg.dropped.%d........", attnum);
		namestrcpy(&(attStruct->attname), newattname);

		simple_heap_update(attr_rel, &tuple->t_self, tuple);

		/* keep the system catalog indexes current */
		CatalogUpdateIndexes(attr_rel, tuple);
	}

	/*
	 * Because updating the pg_attribute row will trigger a relcache flush for
	 * the target relation, we need not do anything else to notify other
	 * backends of the change.
	 */

	heap_close(attr_rel, RowExclusiveLock);

	if (attnum > 0)
		RemoveStatistics(relid, attnum);

	relation_close(rel, NoLock);
}

/*
 *		RemoveAttrDefault
 *
 * If the specified relation/attribute has a default, remove it.
 * (If no default, raise error if complain is true, else return quietly.)
 */
void
RemoveAttrDefault(Oid relid, AttrNumber attnum,
				  DropBehavior behavior, bool complain)
{
	Relation	attrdef_rel;
	ScanKeyData scankeys[2];
	SysScanDesc scan;
	HeapTuple	tuple;
	bool		found = false;

	attrdef_rel = heap_open(AttrDefaultRelationId, RowExclusiveLock);

	ScanKeyInit(&scankeys[0],
				Anum_pg_attrdef_adrelid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(relid));
	ScanKeyInit(&scankeys[1],
				Anum_pg_attrdef_adnum,
				BTEqualStrategyNumber, F_INT2EQ,
				Int16GetDatum(attnum));

	scan = systable_beginscan(attrdef_rel, AttrDefaultIndexId, true,
							  SnapshotNow, 2, scankeys);

	/* There should be at most one matching tuple, but we loop anyway */
	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
	{
		ObjectAddress object;

		object.classId = AttrDefaultRelationId;
		object.objectId = HeapTupleGetOid(tuple);