heap.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 2,069 行 · 第 1/4 页

	 * pinned.
	 */
	if (relkind != RELKIND_VIEW && relkind != RELKIND_COMPOSITE_TYPE)
	{
		dpp = SysAtt;
		for (i = 0; i < -1 - FirstLowInvalidHeapAttributeNumber; i++)
		{
			if (tupdesc->tdhasoid ||
				(*dpp)->attnum != ObjectIdAttributeNumber)
			{
				Form_pg_attribute attStruct;

				tup = heap_addheader(Natts_pg_attribute,
									 false,
									 ATTRIBUTE_TUPLE_SIZE,
									 (void *) *dpp);

				/* Fill in the correct relation OID in the copied tuple */
				attStruct = (Form_pg_attribute) GETSTRUCT(tup);
				attStruct->attrelid = new_rel_oid;

				/*
				 * 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,
					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;

	/*
	 * Here we insert bogus estimates of the size of the new relation. In
	 * reality, of course, the new relation has 0 tuples and pages, and if
	 * we were tracking these statistics accurately then we'd set the
	 * fields that way.  But at present the stats will be updated only by
	 * VACUUM or CREATE INDEX, and the user might insert a lot of tuples
	 * before he gets around to doing either of those.	So, instead of
	 * saying the relation is empty, we insert guesstimates.  The point is
	 * to keep the optimizer from making really stupid choices on
	 * never-yet-vacuumed tables; so the estimates need only be large
	 * enough to discourage the optimizer from using nested-loop plans.
	 * With this hack, nested-loop plans will be preferred only after the
	 * table has been proven to be small by VACUUM or CREATE INDEX.
	 * Maintaining the stats on-the-fly would solve the problem more
	 * cleanly, but the overhead of that would likely cost more than it'd
	 * save. (NOTE: CREATE INDEX inserts the same bogus estimates if it
	 * finds the relation has 0 rows and pages. See index.c.)
	 */
	switch (relkind)
	{
		case RELKIND_RELATION:
		case RELKIND_INDEX:
		case RELKIND_TOASTVALUE:
			new_rel_reltup->relpages = 10;		/* bogus estimates */
			new_rel_reltup->reltuples = 1000;
			break;
		case RELKIND_SEQUENCE:
			new_rel_reltup->relpages = 1;
			new_rel_reltup->reltuples = 1;
			break;
		default:				/* views, etc */
			new_rel_reltup->relpages = 0;
			new_rel_reltup->reltuples = 0;
			break;
	}

	new_rel_reltup->relowner = GetUserId();
	new_rel_reltup->reltype = new_type_oid;
	new_rel_reltup->relkind = relkind;

	/* ----------------
	 *	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 complex type corresponding to the new relation
 * --------------------------------
 */
static void
AddNewRelationType(const char *typeName,
				   Oid typeNamespace,
				   Oid new_rel_oid,
				   char new_rel_kind,
				   Oid new_type_oid)
{
	/*
	 * We set the I/O procedures of a complex type to record_in and
	 * record_out, so that a user will get an error message not a weird
	 * number if he tries to SELECT a complex type.
	 *
	 * OLD and probably obsolete comments:
	 *
	 * The sizes are set to oid size because it makes implementing sets MUCH
	 * easier, and no one (we hope) uses these fields to figure out how
	 * much space to allocate for the type. An oid is the type used for a
	 * set definition.	When a user requests a set, what they actually get
	 * is the oid of a tuple in the pg_proc catalog, so the size of the
	 * "set" is the size of an oid. Similarly, byval being true makes sets
	 * much easier, and it isn't used by anything else.
	 */
	TypeCreate(typeName,		/* type name */
			   typeNamespace,	/* type namespace */
			   new_type_oid,	/* preassigned oid for type */
			   new_rel_oid,		/* relation oid */
			   new_rel_kind,	/* relation kind */
			   sizeof(Oid),		/* internal size */
			   '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,		/* array element type - irrelevant */
			   InvalidOid,		/* domain base type - irrelevant */
			   NULL,			/* default type value - none */
			   NULL,			/* default type binary representation */
			   true,			/* passed by value */
			   'i',				/* default alignment - same as for OID */
			   'p',				/* Not 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,
						 TupleDesc tupdesc,
						 char relkind,
						 bool shared_relation,
						 OnCommitAction oncommit,
						 bool allow_system_table_mods)
{
	Relation	pg_class_desc;
	Relation	new_rel_desc;
	Oid			new_rel_oid;
	Oid			new_type_oid;

	/*
	 * 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)));

	/*
	 * 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.)
	 *
	 * NB: create a physical file only if it's not a view or type relation.
	 */
	new_rel_desc = heap_create(relname,
							   relnamespace,
							   tupdesc,
							   shared_relation,
							   (relkind != RELKIND_VIEW &&
								relkind != RELKIND_COMPOSITE_TYPE),
							   allow_system_table_mods);

	/* Fetch the relation OID assigned by heap_create */
	new_rel_oid = RelationGetRelid(new_rel_desc);

	/* Assign an OID for the relation's tuple type */
	new_type_oid = newoid();

	/*
	 * 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.
	 */
	pg_class_desc = heap_openr(RelationRelationName, RowExclusiveLock);

	AddNewRelationTuple(pg_class_desc,
						new_rel_desc,
						new_rel_oid,
						new_type_oid,
						relkind);

	/*
	 * 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.
	 */
	AddNewRelationType(relname,
					   relnamespace,
					   new_rel_oid,
					   relkind,
					   new_type_oid);

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

	/*
	 * 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.
	 */
	if (!IsBootstrapProcessingMode())
	{
		ObjectAddress myself,
					referenced;

		myself.classId = RelOid_pg_class;
		myself.objectId = new_rel_oid;
		myself.objectSubId = 0;
		referenced.classId = get_system_catalog_relid(NamespaceRelationName);
		referenced.objectId = relnamespace;
		referenced.objectSubId = 0;
		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
	}

	/*
	 * 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(new_rel_oid, 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 new_rel_oid;
}


/*
 *		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(Relation relation)
{
	Relation	catalogRelation;
	SysScanDesc scan;
	ScanKeyData key;
	HeapTuple	tuple;

	catalogRelation = heap_openr(InheritsRelationName, RowExclusiveLock);

	ScanKeyEntryInitialize(&key, 0x0,
						   Anum_pg_inherits_inhrelid, F_OIDEQ,
						   ObjectIdGetDatum(RelationGetRelid(relation)));

	scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndex, 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_openr(RelationRelationName, 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_openr(AttributeRelationName, RowExclusiveLock);

	/* Use the index to scan only attributes of the target relation */
	ScanKeyEntryInitialize(&key[0], 0x0,
						   Anum_pg_attribute_attrelid, F_OIDEQ,
						   ObjectIdGetDatum(relid));

	scan = systable_beginscan(attrel, AttributeRelidNumIndex, 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_openr(AttributeRelationName, 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);

	/* 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);

	RemoveStatistics(rel, 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_openr(AttrDefaultRelationName, RowExclusiveLock);

	ScanKeyEntryInitialize(&scankeys[0], 0x0,
						   Anum_pg_attrdef_adrelid, F_OIDEQ,