relcache.c

关系型数据库 Postgresql 6.5.2

	/* ----------------
	 *	end the scan and close the attribute relation
	 * ----------------
	 */
	heap_endscan(pg_attribute_scan);
	heap_close(pg_attribute_desc);
}

static void
build_tupdesc_ind(RelationBuildDescInfo buildinfo,
				  Relation relation,
				  u_int natts)
{
	Relation	attrel;
	HeapTuple	atttup;
	Form_pg_attribute attp;
	TupleConstr *constr = (TupleConstr *) palloc(sizeof(TupleConstr));
	AttrDefault *attrdef = NULL;
	int			ndef = 0;
	int			i;

	constr->has_not_null = false;

	attrel = heap_openr(AttributeRelationName);

	for (i = 1; i <= relation->rd_rel->relnatts; i++)
	{
		atttup = (HeapTuple) AttributeNumIndexScan(attrel,
										  RelationGetRelid(relation), i);

		if (!HeapTupleIsValid(atttup))
			elog(ERROR, "cannot find attribute %d of relation %s", i,
				 relation->rd_rel->relname.data);
		attp = (Form_pg_attribute) GETSTRUCT(atttup);

		relation->rd_att->attrs[i - 1] =
			(Form_pg_attribute) palloc(ATTRIBUTE_TUPLE_SIZE);

		memmove((char *) (relation->rd_att->attrs[i - 1]),
				(char *) attp,
				ATTRIBUTE_TUPLE_SIZE);

		/* Update if this attribute have a constraint */
		if (attp->attnotnull)
			constr->has_not_null = true;

		if (attp->atthasdef)
		{
			if (attrdef == NULL)
				attrdef = (AttrDefault *) palloc(relation->rd_rel->relnatts *
												 sizeof(AttrDefault));
			attrdef[ndef].adnum = i;
			attrdef[ndef].adbin = NULL;
			attrdef[ndef].adsrc = NULL;
			ndef++;
		}
	}

	heap_close(attrel);

	if (constr->has_not_null || ndef > 0 || relation->rd_rel->relchecks)
	{
		relation->rd_att->constr = constr;

		if (ndef > 0)			/* DEFAULTs */
		{
			if (ndef < relation->rd_rel->relnatts)
				constr->defval = (AttrDefault *)
					repalloc(attrdef, ndef * sizeof(AttrDefault));
			else
				constr->defval = attrdef;
			constr->num_defval = ndef;
			AttrDefaultFetch(relation);
		}
		else
			constr->num_defval = 0;

		if (relation->rd_rel->relchecks > 0)	/* CHECKs */
		{
			constr->num_check = relation->rd_rel->relchecks;
			constr->check = (ConstrCheck *) palloc(constr->num_check *
												   sizeof(ConstrCheck));
			MemSet(constr->check, 0, constr->num_check * sizeof(ConstrCheck));
			RelCheckFetch(relation);
		}
		else
			constr->num_check = 0;
	}
	else
	{
		pfree(constr);
		relation->rd_att->constr = NULL;
	}

}

/* --------------------------------
 *		RelationBuildRuleLock
 *
 *		Form the relation's rewrite rules from information in
 *		the pg_rewrite system catalog.
 * --------------------------------
 */
static void
RelationBuildRuleLock(Relation relation)
{
	HeapTuple	pg_rewrite_tuple;
	Relation	pg_rewrite_desc;
	TupleDesc	pg_rewrite_tupdesc;
	HeapScanDesc pg_rewrite_scan;
	ScanKeyData key;
	RuleLock   *rulelock;
	int			numlocks;
	RewriteRule **rules;
	int			maxlocks;

	/* ----------------
	 *	form an array to hold the rewrite rules (the array is extended if
	 *	necessary)
	 * ----------------
	 */
	maxlocks = 4;
	rules = (RewriteRule **) palloc(sizeof(RewriteRule *) * maxlocks);
	numlocks = 0;

	/* ----------------
	 *	form a scan key
	 * ----------------
	 */
	ScanKeyEntryInitialize(&key, 0,
						   Anum_pg_rewrite_ev_class,
						   F_OIDEQ,
						   ObjectIdGetDatum(RelationGetRelid(relation)));

	/* ----------------
	 *	open pg_attribute and begin a scan
	 * ----------------
	 */
	pg_rewrite_desc = heap_openr(RewriteRelationName);
	pg_rewrite_scan = heap_beginscan(pg_rewrite_desc, 0, SnapshotNow, 1, &key);
	pg_rewrite_tupdesc = RelationGetDescr(pg_rewrite_desc);

	/* ----------------
	 *	add attribute data to relation->rd_att
	 * ----------------
	 */
	while (HeapTupleIsValid(pg_rewrite_tuple = heap_getnext(pg_rewrite_scan, 0)))
	{
		bool		isnull;
		Datum		ruleaction;
		Datum		rule_evqual_string;
		RewriteRule *rule;

		rule = (RewriteRule *) palloc(sizeof(RewriteRule));

		rule->ruleId = pg_rewrite_tuple->t_data->t_oid;

		rule->event = (int) heap_getattr(pg_rewrite_tuple,
							 Anum_pg_rewrite_ev_type, pg_rewrite_tupdesc,
										 &isnull) - 48;
		rule->attrno = (int) heap_getattr(pg_rewrite_tuple,
							 Anum_pg_rewrite_ev_attr, pg_rewrite_tupdesc,
										  &isnull);
		rule->isInstead = !!heap_getattr(pg_rewrite_tuple,
						  Anum_pg_rewrite_is_instead, pg_rewrite_tupdesc,
										 &isnull);

		ruleaction = heap_getattr(pg_rewrite_tuple,
						   Anum_pg_rewrite_ev_action, pg_rewrite_tupdesc,
								  &isnull);
		rule_evqual_string = heap_getattr(pg_rewrite_tuple,
							 Anum_pg_rewrite_ev_qual, pg_rewrite_tupdesc,
										  &isnull);

		ruleaction = PointerGetDatum(textout((struct varlena *) DatumGetPointer(ruleaction)));
		rule_evqual_string = PointerGetDatum(textout((struct varlena *) DatumGetPointer(rule_evqual_string)));

		rule->actions = (List *) stringToNode(DatumGetPointer(ruleaction));
		rule->qual = (Node *) stringToNode(DatumGetPointer(rule_evqual_string));

		rules[numlocks++] = rule;
		if (numlocks == maxlocks)
		{
			maxlocks *= 2;
			rules = (RewriteRule **) repalloc(rules, sizeof(RewriteRule *) * maxlocks);
		}
	}

	/* ----------------
	 *	end the scan and close the attribute relation
	 * ----------------
	 */
	heap_endscan(pg_rewrite_scan);
	heap_close(pg_rewrite_desc);

	/* ----------------
	 *	form a RuleLock and insert into relation
	 * ----------------
	 */
	rulelock = (RuleLock *) palloc(sizeof(RuleLock));
	rulelock->numLocks = numlocks;
	rulelock->rules = rules;

	relation->rd_rules = rulelock;
	return;
}


/* --------------------------------
 *		RelationBuildDesc
 *
 *		To build a relation descriptor, we have to allocate space,
 *		open the underlying unix file and initialize the following
 *		fields:
 *
 *	File				   rd_fd;		 open file descriptor
 *	int					   rd_nblocks;	 number of blocks in rel
 *										 it will be set in ambeginscan()
 *	uint16				   rd_refcnt;	 reference count
 *	Form_pg_am			   rd_am;		 AM tuple
 *	Form_pg_class		   rd_rel;		 RELATION tuple
 *	Oid					   rd_id;		 relations's object id
 *	Pointer				   lockInfo;	 ptr. to misc. info.
 *	TupleDesc			   rd_att;		 tuple desciptor
 *
 *		Note: rd_ismem (rel is in-memory only) is currently unused
 *		by any part of the system.	someday this will indicate that
 *		the relation lives only in the main-memory buffer pool
 *		-cim 2/4/91
 * --------------------------------
 */
static Relation
RelationBuildDesc(RelationBuildDescInfo buildinfo)
{
	File		fd;
	Relation	relation;
	u_int		natts;
	Oid			relid;
	Oid			relam;
	Form_pg_class relp;

	MemoryContext oldcxt;

	HeapTuple	pg_class_tuple;

	oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);

	/* ----------------
	 *	find the tuple in pg_class corresponding to the given relation id
	 * ----------------
	 */
	pg_class_tuple = ScanPgRelation(buildinfo);

	/* ----------------
	 *	if no such tuple exists, return NULL
	 * ----------------
	 */
	if (!HeapTupleIsValid(pg_class_tuple))
	{
		MemoryContextSwitchTo(oldcxt);

		return NULL;
	}

	/* ----------------
	 *	get information from the pg_class_tuple
	 * ----------------
	 */
	relid = pg_class_tuple->t_data->t_oid;
	relp = (Form_pg_class) GETSTRUCT(pg_class_tuple);
	natts = relp->relnatts;

	/* ----------------
	 *	allocate storage for the relation descriptor,
	 *	initialize relation->rd_rel and get the access method id.
	 * ----------------
	 */
	relation = AllocateRelationDesc(natts, relp);
	relam = relation->rd_rel->relam;

	/* ----------------
	 *	initialize the relation's relation id (relation->rd_id)
	 * ----------------
	 */
	RelationGetRelid(relation) = relid;

	/* ----------------
	 *	initialize relation->rd_refcnt
	 * ----------------
	 */
	RelationSetReferenceCount(relation, 1);

	/* ----------------
	 *	 normal relations are not nailed into the cache
	 * ----------------
	 */
	relation->rd_isnailed = false;

	/* ----------------
	 *	initialize the access method information (relation->rd_am)
	 * ----------------
	 */
	if (OidIsValid(relam))
		relation->rd_am = (Form_pg_am) AccessMethodObjectIdGetForm(relam);

	/* ----------------
	 *	initialize the tuple descriptor (relation->rd_att).
	 *	remember, rd_att is an array of attribute pointers that lives
	 *	off the end of the relation descriptor structure so space was
	 *	already allocated for it by AllocateRelationDesc.
	 * ----------------
	 */
	RelationBuildTupleDesc(buildinfo, relation, natts);

	/* ----------------
	 *	initialize rules that affect this relation
	 * ----------------
	 */
	if (relp->relhasrules)
		RelationBuildRuleLock(relation);
	else
		relation->rd_rules = NULL;

	/* Triggers */
	if (relp->reltriggers > 0)
		RelationBuildTriggers(relation);
	else
		relation->trigdesc = NULL;

	/* ----------------
	 *	initialize index strategy and support information for this relation
	 * ----------------
	 */
	if (OidIsValid(relam))
		IndexedAccessMethodInitialize(relation);

	/* ----------------
	 *	initialize the relation lock manager information
	 * ----------------
	 */
	RelationInitLockInfo(relation);		/* see lmgr.c */

	/* ----------------
	 *	open the relation and assign the file descriptor returned
	 *	by the storage manager code to rd_fd.
	 * ----------------
	 */
	fd = smgropen(DEFAULT_SMGR, relation);

	Assert(fd >= -1);
	if (fd == -1)
		elog(NOTICE, "RelationIdBuildRelation: smgropen(%s): %m",
			 &relp->relname);

	relation->rd_fd = fd;

	/* ----------------
	 *	insert newly created relation into proper relcaches,
	 *	restore memory context and return the new reldesc.
	 * ----------------
	 */
	RelationCacheInsert(relation);

	/* -------------------
	 *	free the memory allocated for pg_class_tuple
	 *	and for lock data pointed to by pg_class_tuple
	 * -------------------
	 */
	pfree(pg_class_tuple);

	MemoryContextSwitchTo(oldcxt);

	return relation;
}

static void
IndexedAccessMethodInitialize(Relation relation)
{
	IndexStrategy strategy;
	RegProcedure *support;
	int			natts;
	Size		stratSize;
	Size		supportSize;
	uint16		relamstrategies;
	uint16		relamsupport;

	natts = relation->rd_rel->relnatts;
	relamstrategies = relation->rd_am->amstrategies;
	stratSize = AttributeNumberGetIndexStrategySize(natts, relamstrategies);
	strategy = (IndexStrategy) palloc(stratSize);
	relamsupport = relation->rd_am->amsupport;

	if (relamsupport > 0)
	{
		supportSize = natts * (relamsupport * sizeof(RegProcedure));
		support = (RegProcedure *) palloc(supportSize);
	}
	else
		support = (RegProcedure *) NULL;

	IndexSupportInitialize(strategy, support,
						   relation->rd_att->attrs[0]->attrelid,
						   relation->rd_rel->relam,
						   relamstrategies, relamsupport, natts);

	RelationSetIndexSupport(relation, strategy, support);
}

/* --------------------------------
 *		formrdesc
 *
 *		This is a special version of RelationBuildDesc()
 *		used by RelationInitialize() in initializing the
 *		relcache.  The system relation descriptors built
 *		here are all nailed in the descriptor caches, for
 *		bootstrapping.
 * --------------------------------
 */
static void
formrdesc(char *relationName,
		  u_int natts,
		  FormData_pg_attribute *att)
{
	Relation	relation;
	Size		len;
	int			i;

	/* ----------------
	 *	allocate new relation desc
	 * ----------------
	 */
	len = sizeof(RelationData);
	relation = (Relation) palloc(len);
	MemSet((char *) relation, 0, len);

	/* ----------------
	 *	don't open the unix file yet..
	 * ----------------
	 */
	relation->rd_fd = -1;

	/* ----------------
	 *	initialize reference count
	 * ----------------
	 */
	RelationSetReferenceCount(relation, 1);

	/* ----------------
	 *	initialize relation tuple form
	 * ----------------
	 */
	relation->rd_rel = (Form_pg_class)
		palloc((Size) (sizeof(*relation->rd_rel)));
	MemSet(relation->rd_rel, 0, sizeof(FormData_pg_class));
	namestrcpy(&relation->rd_rel->relname, relationName);

	/* ----------------
	   initialize attribute tuple form
	*/
	relation->rd_att = CreateTemplateTupleDesc(natts);

	/*
	 * For debugging purposes, it's important to distinguish between
	 * shared and non-shared relations, even at bootstrap time.  There's
	 * code in the buffer manager that traces allocations that has to know
	 * about this.
	 */

	if (IsSystemRelationName(relationName))
	{
		relation->rd_rel->relowner = 6; /* XXX use sym const */
		relation->rd_rel->relisshared = IsSharedSystemRelationName(relationName);
	}
	else
	{
		relation->rd_rel->relowner = 0;
		relation->rd_rel->relisshared = false;
	}

	relation->rd_rel->relpages = 1;		/* XXX */
	relation->rd_rel->reltuples = 1;	/* XXX */
	relation->rd_rel->relkind = RELKIND_RELATION;
	relation->rd_rel->relnatts = (uint16) natts;
	relation->rd_isnailed = true;

	/* ----------------
	 *	initialize tuple desc info
	 * ----------------
	 */
	for (i = 0; i < natts; i++)
	{
		relation->rd_att->attrs[i] = (Form_pg_attribute) palloc(ATTRIBUTE_TUPLE_SIZE);

		MemSet((char *) relation->rd_att->attrs[i], 0,
			   ATTRIBUTE_TUPLE_SIZE);
		memmove((char *) relation->rd_att->attrs[i],
				(char *) &att[i],
				ATTRIBUTE_TUPLE_SIZE);
	}

	/* ----------------
	 *	initialize relation id
	 * ----------------
	 */
	RelationGetRelid(relation) = relation->rd_att->attrs[0]->attrelid;

	/* ----------------
	 *	add new reldesc to relcache
	 * ----------------
	 */
	RelationCacheInsert(relation);

	RelationInitLockInfo(relation);

	/*
	 * Determining this requires a scan on pg_class, but to do the scan
	 * the rdesc for pg_class must already exist.  Therefore we must do
	 * the check (and possible set) after cache insertion.
	 */
	relation->rd_rel->relhasindex =
		CatalogHasIndex(relationName, RelationGetRelid(relation));
}


/* ----------------------------------------------------------------
 *				 Relation Descriptor Lookup Interface
 * ----------------------------------------------------------------
 */