namespace.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	/* deconstruct the name list */
	DeconstructQualifiedName(names, &schemaname, &funcname);

	if (schemaname)
	{
		/* use exact schema given */
		namespaceId = LookupExplicitNamespace(schemaname);
	}
	else
	{
		/* flag to indicate we need namespace search */
		namespaceId = InvalidOid;
		recomputeNamespacePath();
	}

	/* Search syscache by name only */
	catlist = SearchSysCacheList(PROCNAMEARGSNSP, 1,
								 CStringGetDatum(funcname),
								 0, 0, 0);

	for (i = 0; i < catlist->n_members; i++)
	{
		HeapTuple	proctup = &catlist->members[i]->tuple;
		Form_pg_proc procform = (Form_pg_proc) GETSTRUCT(proctup);
		int			pronargs = procform->pronargs;
		int			pathpos = 0;
		FuncCandidateList newResult;

		/* Ignore if it doesn't match requested argument count */
		if (nargs >= 0 && pronargs != nargs)
			continue;

		if (OidIsValid(namespaceId))
		{
			/* Consider only procs in specified namespace */
			if (procform->pronamespace != namespaceId)
				continue;
			/* No need to check args, they must all be different */
		}
		else
		{
			/* Consider only procs that are in the search path */
			ListCell   *nsp;

			foreach(nsp, namespaceSearchPath)
			{
				if (procform->pronamespace == lfirst_oid(nsp))
					break;
				pathpos++;
			}
			if (nsp == NULL)
				continue;		/* proc is not in search path */

			/*
			 * Okay, it's in the search path, but does it have the same
			 * arguments as something we already accepted?	If so, keep only
			 * the one that appears earlier in the search path.
			 *
			 * If we have an ordered list from SearchSysCacheList (the normal
			 * case), then any conflicting proc must immediately adjoin this
			 * one in the list, so we only need to look at the newest result
			 * item.  If we have an unordered list, we have to scan the whole
			 * result list.
			 */
			if (resultList)
			{
				FuncCandidateList prevResult;

				if (catlist->ordered)
				{
					if (pronargs == resultList->nargs &&
						memcmp(procform->proargtypes.values,
							   resultList->args,
							   pronargs * sizeof(Oid)) == 0)
						prevResult = resultList;
					else
						prevResult = NULL;
				}
				else
				{
					for (prevResult = resultList;
						 prevResult;
						 prevResult = prevResult->next)
					{
						if (pronargs == prevResult->nargs &&
							memcmp(procform->proargtypes.values,
								   prevResult->args,
								   pronargs * sizeof(Oid)) == 0)
							break;
					}
				}
				if (prevResult)
				{
					/* We have a match with a previous result */
					Assert(pathpos != prevResult->pathpos);
					if (pathpos > prevResult->pathpos)
						continue;		/* keep previous result */
					/* replace previous result */
					prevResult->pathpos = pathpos;
					prevResult->oid = HeapTupleGetOid(proctup);
					continue;	/* args are same, of course */
				}
			}
		}

		/*
		 * Okay to add it to result list
		 */
		newResult = (FuncCandidateList)
			palloc(sizeof(struct _FuncCandidateList) - sizeof(Oid)
				   + pronargs * sizeof(Oid));
		newResult->pathpos = pathpos;
		newResult->oid = HeapTupleGetOid(proctup);
		newResult->nargs = pronargs;
		memcpy(newResult->args, procform->proargtypes.values,
			   pronargs * sizeof(Oid));

		newResult->next = resultList;
		resultList = newResult;
	}

	ReleaseSysCacheList(catlist);

	return resultList;
}

/*
 * FunctionIsVisible
 *		Determine whether a function (identified by OID) is visible in the
 *		current search path.  Visible means "would be found by searching
 *		for the unqualified function name with exact argument matches".
 */
bool
FunctionIsVisible(Oid funcid)
{
	HeapTuple	proctup;
	Form_pg_proc procform;
	Oid			pronamespace;
	bool		visible;

	proctup = SearchSysCache(PROCOID,
							 ObjectIdGetDatum(funcid),
							 0, 0, 0);
	if (!HeapTupleIsValid(proctup))
		elog(ERROR, "cache lookup failed for function %u", funcid);
	procform = (Form_pg_proc) GETSTRUCT(proctup);

	recomputeNamespacePath();

	/*
	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
	 * the system namespace are surely in the path and so we needn't even do
	 * list_member_oid() for them.
	 */
	pronamespace = procform->pronamespace;
	if (pronamespace != PG_CATALOG_NAMESPACE &&
		!list_member_oid(namespaceSearchPath, pronamespace))
		visible = false;
	else
	{
		/*
		 * If it is in the path, it might still not be visible; it could be
		 * hidden by another proc of the same name and arguments earlier in
		 * the path.  So we must do a slow check to see if this is the same
		 * proc that would be found by FuncnameGetCandidates.
		 */
		char	   *proname = NameStr(procform->proname);
		int			nargs = procform->pronargs;
		FuncCandidateList clist;

		visible = false;

		clist = FuncnameGetCandidates(list_make1(makeString(proname)), nargs);

		for (; clist; clist = clist->next)
		{
			if (memcmp(clist->args, procform->proargtypes.values,
					   nargs * sizeof(Oid)) == 0)
			{
				/* Found the expected entry; is it the right proc? */
				visible = (clist->oid == funcid);
				break;
			}
		}
	}

	ReleaseSysCache(proctup);

	return visible;
}


/*
 * OpernameGetCandidates
 *		Given a possibly-qualified operator name and operator kind,
 *		retrieve a list of the possible matches.
 *
 * If oprkind is '\0', we return all operators matching the given name,
 * regardless of arguments.
 *
 * We search a single namespace if the operator name is qualified, else
 * all namespaces in the search path.  The return list will never contain
 * multiple entries with identical argument lists --- in the multiple-
 * namespace case, we arrange for entries in earlier namespaces to mask
 * identical entries in later namespaces.
 *
 * The returned items always have two args[] entries --- one or the other
 * will be InvalidOid for a prefix or postfix oprkind.	nargs is 2, too.
 */
FuncCandidateList
OpernameGetCandidates(List *names, char oprkind)
{
	FuncCandidateList resultList = NULL;
	char	   *resultSpace = NULL;
	int			nextResult = 0;
	char	   *schemaname;
	char	   *opername;
	Oid			namespaceId;
	CatCList   *catlist;
	int			i;

	/* deconstruct the name list */
	DeconstructQualifiedName(names, &schemaname, &opername);

	if (schemaname)
	{
		/* use exact schema given */
		namespaceId = LookupExplicitNamespace(schemaname);
	}
	else
	{
		/* flag to indicate we need namespace search */
		namespaceId = InvalidOid;
		recomputeNamespacePath();
	}

	/* Search syscache by name only */
	catlist = SearchSysCacheList(OPERNAMENSP, 1,
								 CStringGetDatum(opername),
								 0, 0, 0);

	/*
	 * In typical scenarios, most if not all of the operators found by the
	 * catcache search will end up getting returned; and there can be quite a
	 * few, for common operator names such as '=' or '+'.  To reduce the time
	 * spent in palloc, we allocate the result space as an array large enough
	 * to hold all the operators.  The original coding of this routine did a
	 * separate palloc for each operator, but profiling revealed that the
	 * pallocs used an unreasonably large fraction of parsing time.
	 */
#define SPACE_PER_OP MAXALIGN(sizeof(struct _FuncCandidateList) + sizeof(Oid))

	if (catlist->n_members > 0)
		resultSpace = palloc(catlist->n_members * SPACE_PER_OP);

	for (i = 0; i < catlist->n_members; i++)
	{
		HeapTuple	opertup = &catlist->members[i]->tuple;
		Form_pg_operator operform = (Form_pg_operator) GETSTRUCT(opertup);
		int			pathpos = 0;
		FuncCandidateList newResult;

		/* Ignore operators of wrong kind, if specific kind requested */
		if (oprkind && operform->oprkind != oprkind)
			continue;

		if (OidIsValid(namespaceId))
		{
			/* Consider only opers in specified namespace */
			if (operform->oprnamespace != namespaceId)
				continue;
			/* No need to check args, they must all be different */
		}
		else
		{
			/* Consider only opers that are in the search path */
			ListCell   *nsp;

			foreach(nsp, namespaceSearchPath)
			{
				if (operform->oprnamespace == lfirst_oid(nsp))
					break;
				pathpos++;
			}
			if (nsp == NULL)
				continue;		/* oper is not in search path */

			/*
			 * Okay, it's in the search path, but does it have the same
			 * arguments as something we already accepted?	If so, keep only
			 * the one that appears earlier in the search path.
			 *
			 * If we have an ordered list from SearchSysCacheList (the normal
			 * case), then any conflicting oper must immediately adjoin this
			 * one in the list, so we only need to look at the newest result
			 * item.  If we have an unordered list, we have to scan the whole
			 * result list.
			 */
			if (resultList)
			{
				FuncCandidateList prevResult;

				if (catlist->ordered)
				{
					if (operform->oprleft == resultList->args[0] &&
						operform->oprright == resultList->args[1])
						prevResult = resultList;
					else
						prevResult = NULL;
				}
				else
				{
					for (prevResult = resultList;
						 prevResult;
						 prevResult = prevResult->next)
					{
						if (operform->oprleft == prevResult->args[0] &&
							operform->oprright == prevResult->args[1])
							break;
					}
				}
				if (prevResult)
				{
					/* We have a match with a previous result */
					Assert(pathpos != prevResult->pathpos);
					if (pathpos > prevResult->pathpos)
						continue;		/* keep previous result */
					/* replace previous result */
					prevResult->pathpos = pathpos;
					prevResult->oid = HeapTupleGetOid(opertup);
					continue;	/* args are same, of course */
				}
			}
		}

		/*
		 * Okay to add it to result list
		 */
		newResult = (FuncCandidateList) (resultSpace + nextResult);
		nextResult += SPACE_PER_OP;

		newResult->pathpos = pathpos;
		newResult->oid = HeapTupleGetOid(opertup);
		newResult->nargs = 2;
		newResult->args[0] = operform->oprleft;
		newResult->args[1] = operform->oprright;
		newResult->next = resultList;
		resultList = newResult;
	}

	ReleaseSysCacheList(catlist);

	return resultList;
}

/*
 * OperatorIsVisible
 *		Determine whether an operator (identified by OID) is visible in the
 *		current search path.  Visible means "would be found by searching
 *		for the unqualified operator name with exact argument matches".
 */
bool
OperatorIsVisible(Oid oprid)
{
	HeapTuple	oprtup;
	Form_pg_operator oprform;
	Oid			oprnamespace;
	bool		visible;

	oprtup = SearchSysCache(OPEROID,
							ObjectIdGetDatum(oprid),
							0, 0, 0);
	if (!HeapTupleIsValid(oprtup))
		elog(ERROR, "cache lookup failed for operator %u", oprid);
	oprform = (Form_pg_operator) GETSTRUCT(oprtup);

	recomputeNamespacePath();

	/*
	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
	 * the system namespace are surely in the path and so we needn't even do
	 * list_member_oid() for them.
	 */
	oprnamespace = oprform->oprnamespace;
	if (oprnamespace != PG_CATALOG_NAMESPACE &&
		!list_member_oid(namespaceSearchPath, oprnamespace))
		visible = false;
	else
	{
		/*
		 * If it is in the path, it might still not be visible; it could be
		 * hidden by another operator of the same name and arguments earlier
		 * in the path.  So we must do a slow check to see if this is the same
		 * operator that would be found by OpernameGetCandidates.
		 */
		char	   *oprname = NameStr(oprform->oprname);
		FuncCandidateList clist;

		visible = false;

		clist = OpernameGetCandidates(list_make1(makeString(oprname)),
									  oprform->oprkind);

		for (; clist; clist = clist->next)
		{
			if (clist->args[0] == oprform->oprleft &&
				clist->args[1] == oprform->oprright)
			{
				/* Found the expected entry; is it the right op? */
				visible = (clist->oid == oprid);
				break;
			}
		}
	}

	ReleaseSysCache(oprtup);

	return visible;
}


/*
 * OpclassnameGetOpcid
 *		Try to resolve an unqualified index opclass name.
 *		Returns OID if opclass found in search path, else InvalidOid.
 *
 * This is essentially the same as TypenameGetTypid, but we have to have
 * an extra argument for the index AM OID.
 */
Oid
OpclassnameGetOpcid(Oid amid, const char *opcname)
{
	Oid			opcid;
	ListCell   *l;

	recomputeNamespacePath();

	foreach(l, namespaceSearchPath)
	{
		Oid			namespaceId = lfirst_oid(l);

		opcid = GetSysCacheOid(CLAAMNAMENSP,
							   ObjectIdGetDatum(amid),
							   PointerGetDatum(opcname),
							   ObjectIdGetDatum(namespaceId),
							   0);
		if (OidIsValid(opcid))
			return opcid;
	}

	/* Not found in path */
	return InvalidOid;
}

/*
 * OpclassIsVisible
 *		Determine whether an opclass (identified by OID) is visible in the
 *		current search path.  Visible means "would be found by searching
 *		for the unqualified opclass name".
 */
bool
OpclassIsVisible(Oid opcid)
{
	HeapTuple	opctup;
	Form_pg_opclass opcform;
	Oid			opcnamespace;
	bool		visible;

	opctup = SearchSysCache(CLAOID,
							ObjectIdGetDatum(opcid),
							0, 0, 0);
	if (!HeapTupleIsValid(opctup))
		elog(ERROR, "cache lookup failed for opclass %u", opcid);
	opcform = (Form_pg_opclass) GETSTRUCT(opctup);

	recomputeNamespacePath();

	/*
	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
	 * the system namespace are surely in the path and so we needn't even do
	 * list_member_oid() for them.
	 */
	opcnamespace = opcform->opcnamespace;
	if (opcnamespace != PG_CATALOG_NAMESPACE &&
		!list_member_oid(namespaceSearchPath, opcnamespace))
		visible = false;
	else
	{
		/*
		 * If it is in the path, it might still not be visible; it could be