static void
PLy_input_datum_func2(PLyDatumToOb *arg, Oid typeOid, HeapTuple typeTup)
{
	Form_pg_type typeStruct = (Form_pg_type) GETSTRUCT(typeTup);
	Oid			element_type = get_element_type(typeOid);

	/* Get the type's conversion information */
	perm_fmgr_info(typeStruct->typoutput, &arg->typfunc);
	arg->typoid = HeapTupleGetOid(typeTup);
	arg->typmod = -1;
	arg->typioparam = getTypeIOParam(typeTup);
	arg->typbyval = typeStruct->typbyval;
	arg->typlen = typeStruct->typlen;
	arg->typalign = typeStruct->typalign;

	/* Determine which kind of Python object we will convert to */
	switch (getBaseType(element_type ? element_type : typeOid))
	{
		case BOOLOID:
			arg->func = PLyBool_FromBool;
			break;
		case FLOAT4OID:
			arg->func = PLyFloat_FromFloat4;
			break;
		case FLOAT8OID:
			arg->func = PLyFloat_FromFloat8;
			break;
		case NUMERICOID:
			arg->func = PLyFloat_FromNumeric;
			break;
		case INT2OID:
			arg->func = PLyInt_FromInt16;
			break;
		case INT4OID:
			arg->func = PLyInt_FromInt32;
			break;
		case INT8OID:
			arg->func = PLyLong_FromInt64;
			break;
		case BYTEAOID:
			arg->func = PLyBytes_FromBytea;
			break;
		default:
			arg->func = PLyString_FromDatum;
			break;
	}

	if (element_type)
	{
		char		dummy_delim;
		Oid			funcid;

		arg->elm = PLy_malloc0(sizeof(*arg->elm));
		arg->elm->func = arg->func;
		arg->func = PLyList_FromArray;
		arg->elm->typoid = element_type;
		arg->elm->typmod = -1;
		get_type_io_data(element_type, IOFunc_output,
						 &arg->elm->typlen, &arg->elm->typbyval, &arg->elm->typalign, &dummy_delim,
						 &arg->elm->typioparam, &funcid);
		perm_fmgr_info(funcid, &arg->elm->typfunc);
	}
}

/*
 * PrepareForTupleInvalidation
 *		Detect whether invalidation of this tuple implies invalidation
 *		of catalog/relation cache entries; if so, register inval events.
 */
static void
PrepareForTupleInvalidation(Relation relation, HeapTuple tuple)
{
	Oid			tupleRelId;
	Oid			databaseId;
	Oid			relationId;

	/* Do nothing during bootstrap */
	if (IsBootstrapProcessingMode())
		return;

	/*
	 * We only need to worry about invalidation for tuples that are in system
	 * relations; user-relation tuples are never in catcaches and can't affect
	 * the relcache either.
	 */
	if (!IsSystemRelation(relation))
		return;

	/*
	 * TOAST tuples can likewise be ignored here. Note that TOAST tables are
	 * considered system relations so they are not filtered by the above test.
	 */
	if (IsToastRelation(relation))
		return;

	/*
	 * First let the catcache do its thing
	 */
	PrepareToInvalidateCacheTuple(relation, tuple,
								  RegisterCatcacheInvalidation);

	/*
	 * Now, is this tuple one of the primary definers of a relcache entry?
	 */
	tupleRelId = RelationGetRelid(relation);

	if (tupleRelId == RelationRelationId)
	{
		Form_pg_class classtup = (Form_pg_class) GETSTRUCT(tuple);
		RelFileNode rnode;

		relationId = HeapTupleGetOid(tuple);
		if (classtup->relisshared)
			databaseId = InvalidOid;
		else
			databaseId = MyDatabaseId;

		/*
		 * We need to send out an smgr inval as well as a relcache inval. This
		 * is needed because other backends might possibly possess smgr cache
		 * but not relcache entries for the target relation.
		 *
		 * Note: during a pg_class row update that assigns a new relfilenode
		 * or reltablespace value, we will be called on both the old and new
		 * tuples, and thus will broadcast invalidation messages showing both
		 * the old and new RelFileNode values.	This ensures that other
		 * backends will close smgr references to the old file.
		 *
		 * XXX possible future cleanup: it might be better to trigger smgr
		 * flushes explicitly, rather than indirectly from pg_class updates.
		 */
		if (classtup->reltablespace)
			rnode.spcNode = classtup->reltablespace;
		else
			rnode.spcNode = MyDatabaseTableSpace;
		rnode.dbNode = databaseId;
		rnode.relNode = classtup->relfilenode;
		RegisterSmgrInvalidation(rnode);
	}
	else if (tupleRelId == AttributeRelationId)
	{
		Form_pg_attribute atttup = (Form_pg_attribute) GETSTRUCT(tuple);

		relationId = atttup->attrelid;

		/*
		 * KLUGE ALERT: we always send the relcache event with MyDatabaseId,
		 * even if the rel in question is shared (which we can't easily tell).
		 * This essentially means that only backends in this same database
		 * will react to the relcache flush request. This is in fact
		 * appropriate, since only those backends could see our pg_attribute
		 * change anyway.  It looks a bit ugly though.
		 */
		databaseId = MyDatabaseId;
	}
	else
		return;

	/*
	 * Yes.  We need to register a relcache invalidation event.
	 */
	RegisterRelcacheInvalidation(databaseId, relationId);
}

/*
 * CacheInvalidateHeapTuple
 *		Register the given tuple for invalidation at end of command
 *		(ie, current command is creating or outdating this tuple).
 *		Also, detect whether a relcache invalidation is implied.
 *
 * For an insert or delete, tuple is the target tuple and newtuple is NULL.
 * For an update, we are called just once, with tuple being the old tuple
 * version and newtuple the new version.  This allows avoidance of duplicate
 * effort during an update.
 */
void
CacheInvalidateHeapTuple(Relation relation,
						 HeapTuple tuple,
						 HeapTuple newtuple)
{
	Oid			tupleRelId;
	Oid			databaseId;
	Oid			relationId;

	/* Do nothing during bootstrap */
	if (IsBootstrapProcessingMode())
		return;

	/*
	 * We only need to worry about invalidation for tuples that are in system
	 * catalogs; user-relation tuples are never in catcaches and can't affect
	 * the relcache either.
	 */
	if (!IsCatalogRelation(relation))
		return;

	/*
	 * IsCatalogRelation() will return true for TOAST tables of system
	 * catalogs, but we don't care about those, either.
	 */
	if (IsToastRelation(relation))
		return;

	/*
	 * If we're not prepared to queue invalidation messages for this
	 * subtransaction level, get ready now.
	 */
	PrepareInvalidationState();

	/*
	 * First let the catcache do its thing
	 */
	tupleRelId = RelationGetRelid(relation);
	if (RelationInvalidatesSnapshotsOnly(tupleRelId))
	{
		databaseId = IsSharedRelation(tupleRelId) ? InvalidOid : MyDatabaseId;
		RegisterSnapshotInvalidation(databaseId, tupleRelId);
	}
	else
		PrepareToInvalidateCacheTuple(relation, tuple, newtuple,
									  RegisterCatcacheInvalidation);

	/*
	 * Now, is this tuple one of the primary definers of a relcache entry?
	 *
	 * Note we ignore newtuple here; we assume an update cannot move a tuple
	 * from being part of one relcache entry to being part of another.
	 */
	if (tupleRelId == RelationRelationId)
	{
		Form_pg_class classtup = (Form_pg_class) GETSTRUCT(tuple);

		relationId = HeapTupleGetOid(tuple);
		if (classtup->relisshared)
			databaseId = InvalidOid;
		else
			databaseId = MyDatabaseId;
	}
	else if (tupleRelId == AttributeRelationId)
	{
		Form_pg_attribute atttup = (Form_pg_attribute) GETSTRUCT(tuple);

		relationId = atttup->attrelid;

		/*
		 * KLUGE ALERT: we always send the relcache event with MyDatabaseId,
		 * even if the rel in question is shared (which we can't easily tell).
		 * This essentially means that only backends in this same database
		 * will react to the relcache flush request.  This is in fact
		 * appropriate, since only those backends could see our pg_attribute
		 * change anyway.  It looks a bit ugly though.  (In practice, shared
		 * relations can't have schema changes after bootstrap, so we should
		 * never come here for a shared rel anyway.)
		 */
		databaseId = MyDatabaseId;
	}
	else if (tupleRelId == IndexRelationId)
	{
		Form_pg_index indextup = (Form_pg_index) GETSTRUCT(tuple);

		/*
		 * When a pg_index row is updated, we should send out a relcache inval
		 * for the index relation.  As above, we don't know the shared status
		 * of the index, but in practice it doesn't matter since indexes of
//.........这里部分代码省略.........

/*
 * Drop a table space
 *
 * Be careful to check that the tablespace is empty.
 */
void
DropTableSpace(DropTableSpaceStmt *stmt)
{
#ifdef HAVE_SYMLINK
	char	   *tablespacename = stmt->tablespacename;
	HeapScanDesc scandesc;
	Relation	rel;
	HeapTuple	tuple;
	ScanKeyData entry[1];
	Oid			tablespaceoid;

	/*
	 * Find the target tuple
	 */
	rel = heap_open(TableSpaceRelationId, RowExclusiveLock);

	ScanKeyInit(&entry[0],
				Anum_pg_tablespace_spcname,
				BTEqualStrategyNumber, F_NAMEEQ,
				CStringGetDatum(tablespacename));
	scandesc = heap_beginscan(rel, SnapshotNow, 1, entry);
	tuple = heap_getnext(scandesc, ForwardScanDirection);

	if (!HeapTupleIsValid(tuple))
	{
		if (!stmt->missing_ok)
		{
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("tablespace \"%s\" does not exist",
							tablespacename)));
		}
		else
		{
			ereport(NOTICE,
					(errmsg("tablespace \"%s\" does not exist, skipping",
							tablespacename)));
			/* XXX I assume I need one or both of these next two calls */
			heap_endscan(scandesc);
			heap_close(rel, NoLock);
		}
		return;
	}

	tablespaceoid = HeapTupleGetOid(tuple);

	/* Must be tablespace owner */
	if (!pg_tablespace_ownercheck(tablespaceoid, GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_TABLESPACE,
					   tablespacename);

	/* Disallow drop of the standard tablespaces, even by superuser */
	if (tablespaceoid == GLOBALTABLESPACE_OID ||
		tablespaceoid == DEFAULTTABLESPACE_OID)
		aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_TABLESPACE,
					   tablespacename);

	/* DROP hook for the tablespace being removed */
	if (object_access_hook)
	{
		ObjectAccessDrop drop_arg;

		memset(&drop_arg, 0, sizeof(ObjectAccessDrop));
		InvokeObjectAccessHook(OAT_DROP, TableSpaceRelationId,
							   tablespaceoid, 0, &drop_arg);
	}

	/*
	 * Remove the pg_tablespace tuple (this will roll back if we fail below)
	 */
	simple_heap_delete(rel, &tuple->t_self);

	heap_endscan(scandesc);

	/*
	 * Remove any comments or security labels on this tablespace.
	 */
	DeleteSharedComments(tablespaceoid, TableSpaceRelationId);
	DeleteSharedSecurityLabel(tablespaceoid, TableSpaceRelationId);

	/*
	 * Remove dependency on owner.
	 */
	deleteSharedDependencyRecordsFor(TableSpaceRelationId, tablespaceoid, 0);

	/*
	 * Acquire TablespaceCreateLock to ensure that no TablespaceCreateDbspace
	 * is running concurrently.
	 */
	LWLockAcquire(TablespaceCreateLock, LW_EXCLUSIVE);

	/*
	 * Try to remove the physical infrastructure.
	 */
	if (!destroy_tablespace_directories(tablespaceoid, false))
//.........这里部分代码省略.........

/*
 * Alter table space options
 */
void
AlterTableSpaceOptions(AlterTableSpaceOptionsStmt *stmt)
{
	Relation	rel;
	ScanKeyData entry[1];
	HeapScanDesc scandesc;
	HeapTuple	tup;
	Datum		datum;
	Datum		newOptions;
	Datum		repl_val[Natts_pg_tablespace];
	bool		isnull;
	bool		repl_null[Natts_pg_tablespace];
	bool		repl_repl[Natts_pg_tablespace];
	HeapTuple	newtuple;

	/* Search pg_tablespace */
	rel = heap_open(TableSpaceRelationId, RowExclusiveLock);

	ScanKeyInit(&entry[0],
				Anum_pg_tablespace_spcname,
				BTEqualStrategyNumber, F_NAMEEQ,
				CStringGetDatum(stmt->tablespacename));
	scandesc = heap_beginscan(rel, SnapshotNow, 1, entry);
	tup = heap_getnext(scandesc, ForwardScanDirection);
	if (!HeapTupleIsValid(tup))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("tablespace \"%s\" does not exist",
						stmt->tablespacename)));

	/* Must be owner of the existing object */
	if (!pg_tablespace_ownercheck(HeapTupleGetOid(tup), GetUserId()))
		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_TABLESPACE,
					   stmt->tablespacename);

	/* Generate new proposed spcoptions (text array) */
	datum = heap_getattr(tup, Anum_pg_tablespace_spcoptions,
						 RelationGetDescr(rel), &isnull);
	newOptions = transformRelOptions(isnull ? (Datum) 0 : datum,
									 stmt->options, NULL, NULL, false,
									 stmt->isReset);
	(void) tablespace_reloptions(newOptions, true);

	/* Build new tuple. */
	memset(repl_null, false, sizeof(repl_null));
	memset(repl_repl, false, sizeof(repl_repl));
	if (newOptions != (Datum) 0)
		repl_val[Anum_pg_tablespace_spcoptions - 1] = newOptions;
	else
		repl_null[Anum_pg_tablespace_spcoptions - 1] = true;
	repl_repl[Anum_pg_tablespace_spcoptions - 1] = true;
	newtuple = heap_modify_tuple(tup, RelationGetDescr(rel), repl_val,
								 repl_null, repl_repl);

	/* Update system catalog. */
	simple_heap_update(rel, &newtuple->t_self, newtuple);
	CatalogUpdateIndexes(rel, newtuple);
	heap_freetuple(newtuple);

	/* Conclude heap scan. */
	heap_endscan(scandesc);
	heap_close(rel, NoLock);
}

//.........这里部分代码省略.........
	/*
	 * Release 7.0 removed network_ops, timespan_ops, and datetime_ops, so we
	 * ignore those opclass names so the default *_ops is used.  This can be
	 * removed in some later release.  bjm 2000/02/07
	 *
	 * Release 7.1 removes lztext_ops, so suppress that too for a while.  tgl
	 * 2000/07/30
	 *
	 * Release 7.2 renames timestamp_ops to timestamptz_ops, so suppress that
	 * too for awhile.  I'm starting to think we need a better approach. tgl
	 * 2000/10/01
	 *
	 * Release 8.0 removes bigbox_ops (which was dead code for a long while
	 * anyway).  tgl 2003/11/11
	 */
	if (list_length(opclass) == 1)
	{
		char	   *claname = strVal(linitial(opclass));

		if (strcmp(claname, "network_ops") == 0 ||
			strcmp(claname, "timespan_ops") == 0 ||
			strcmp(claname, "datetime_ops") == 0 ||
			strcmp(claname, "lztext_ops") == 0 ||
			strcmp(claname, "timestamp_ops") == 0 ||
			strcmp(claname, "bigbox_ops") == 0)
			opclass = NIL;
	}

	if (opclass == NIL)
	{
		/* no operator class specified, so find the default */
		opClassId = GetDefaultOpClass(attrType, accessMethodId);
		if (!OidIsValid(opClassId))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("data type %s has no default operator class for access method \"%s\"",
							format_type_be(attrType), accessMethodName),
					 errhint("You must specify an operator class for the index or define a default operator class for the data type.")));
		return opClassId;
	}

	/*
	 * Specific opclass name given, so look up the opclass.
	 */

	/* deconstruct the name list */
	DeconstructQualifiedName(opclass, &schemaname, &opcname);

	if (schemaname)
	{
		/* Look in specific schema only */
		Oid			namespaceId;

#if PG_VERSION_NUM >= 90300
		namespaceId = LookupExplicitNamespace(schemaname, false);
#else
		namespaceId = LookupExplicitNamespace(schemaname);
#endif
		tuple = SearchSysCache3(CLAAMNAMENSP,
								ObjectIdGetDatum(accessMethodId),
								PointerGetDatum(opcname),
								ObjectIdGetDatum(namespaceId));
	}
	else
	{
		/* Unqualified opclass name, so search the search path */
		opClassId = OpclassnameGetOpcid(accessMethodId, opcname);
		if (!OidIsValid(opClassId))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("operator class \"%s\" does not exist for access method \"%s\"",
							opcname, accessMethodName)));
		tuple = SearchSysCache1(CLAOID, ObjectIdGetDatum(opClassId));
	}

	if (!HeapTupleIsValid(tuple))
	{
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("operator class \"%s\" does not exist for access method \"%s\"",
						NameListToString(opclass), accessMethodName)));
	}

	/*
	 * Verify that the index operator class accepts this datatype.  Note we
	 * will accept binary compatibility.
	 */
	opClassId = HeapTupleGetOid(tuple);
	opInputType = ((Form_pg_opclass) GETSTRUCT(tuple))->opcintype;

	if (!IsBinaryCoercible(attrType, opInputType))
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("operator class \"%s\" does not accept data type %s",
					  NameListToString(opclass), format_type_be(attrType))));

	ReleaseSysCache(tuple);

	return opClassId;
}

/*
 * regclassin		- converts "classname" to class OID
 *
 * We also accept a numeric OID, for symmetry with the output routine.
 *
 * '-' signifies unknown (OID 0).  In all other cases, the input must
 * match an existing pg_class entry.
 */
Datum
regclassin(PG_FUNCTION_ARGS)
{
	char	   *class_name_or_oid = PG_GETARG_CSTRING(0);
	Oid			result = InvalidOid;
	List	   *names;

	/* '-' ? */
	if (strcmp(class_name_or_oid, "-") == 0)
		PG_RETURN_OID(InvalidOid);

	/* Numeric OID? */
	if (class_name_or_oid[0] >= '0' &&
		class_name_or_oid[0] <= '9' &&
	strspn(class_name_or_oid, "0123456789") == strlen(class_name_or_oid))
	{
		result = DatumGetObjectId(DirectFunctionCall1(oidin,
									CStringGetDatum(class_name_or_oid)));
		PG_RETURN_OID(result);
	}

	/* Else it's a name, possibly schema-qualified */

	/*
	 * In bootstrap mode we assume the given name is not schema-qualified,
	 * and just search pg_class for a match.  This is needed for
	 * initializing other system catalogs (pg_namespace may not exist yet,
	 * and certainly there are no schemas other than pg_catalog).
	 */
	if (IsBootstrapProcessingMode())
	{
		Relation	hdesc;
		ScanKeyData skey[1];
		SysScanDesc sysscan;
		HeapTuple	tuple;

		ScanKeyEntryInitialize(&skey[0], 0x0,
							   (AttrNumber) Anum_pg_class_relname,
							   (RegProcedure) F_NAMEEQ,
							   CStringGetDatum(class_name_or_oid));

		hdesc = heap_openr(RelationRelationName, AccessShareLock);
		sysscan = systable_beginscan(hdesc, ClassNameNspIndex, true,
									 SnapshotNow, 1, skey);

		if (HeapTupleIsValid(tuple = systable_getnext(sysscan)))
			result = HeapTupleGetOid(tuple);
		else
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_TABLE),
					 errmsg("relation \"%s\" does not exist", class_name_or_oid)));

		/* We assume there can be only one match */

		systable_endscan(sysscan);
		heap_close(hdesc, AccessShareLock);

		PG_RETURN_OID(result);
	}

	/*
	 * Normal case: parse the name into components and see if it matches
	 * any pg_class entries in the current search path.
	 */
	names = stringToQualifiedNameList(class_name_or_oid, "regclassin");

	result = RangeVarGetRelid(makeRangeVarFromNameList(names), false);

	PG_RETURN_OID(result);
}

//.........这里部分代码省略.........
		nulls[Anum_pg_proc_proargdefaults - 1] = true;
	values[Anum_pg_proc_prosrc - 1] = CStringGetTextDatum(prosrc);
	if (probin)
		values[Anum_pg_proc_probin - 1] = CStringGetTextDatum(probin);
	else
		nulls[Anum_pg_proc_probin - 1] = true;
	if (proconfig != PointerGetDatum(NULL))
		values[Anum_pg_proc_proconfig - 1] = proconfig;
	else
		nulls[Anum_pg_proc_proconfig - 1] = true;
	/* proacl will be determined later */

	rel = heap_open(ProcedureRelationId, RowExclusiveLock);
	tupDesc = RelationGetDescr(rel);

	/* Check for pre-existing definition */
	oldtup = SearchSysCache3(PROCNAMEARGSNSP,
							 PointerGetDatum(procedureName),
							 PointerGetDatum(parameterTypes),
							 ObjectIdGetDatum(procNamespace));

	if (HeapTupleIsValid(oldtup))
	{
		/* There is one; okay to replace it? */
		Form_pg_proc oldproc = (Form_pg_proc) GETSTRUCT(oldtup);
		Datum		proargnames;
		bool		isnull;

		if (!replace)
			ereport(ERROR,
					(errcode(ERRCODE_DUPLICATE_FUNCTION),
			errmsg("function \"%s\" already exists with same argument types",
				   procedureName)));
		if (!pg_proc_ownercheck(HeapTupleGetOid(oldtup), proowner))
			aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC,
						   procedureName);

		/*
		 * Not okay to change the return type of the existing proc, since
		 * existing rules, views, etc may depend on the return type.
		 */
		if (returnType != oldproc->prorettype ||
			returnsSet != oldproc->proretset)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
					 errmsg("cannot change return type of existing function"),
					 errhint("Use DROP FUNCTION first.")));

		/*
		 * If it returns RECORD, check for possible change of record type
		 * implied by OUT parameters
		 */
		if (returnType == RECORDOID)
		{
			TupleDesc	olddesc;
			TupleDesc	newdesc;

			olddesc = build_function_result_tupdesc_t(oldtup);
			newdesc = build_function_result_tupdesc_d(allParameterTypes,
													  parameterModes,
													  parameterNames);
			if (olddesc == NULL && newdesc == NULL)
				 /* ok, both are runtime-defined RECORDs */ ;
			else if (olddesc == NULL || newdesc == NULL ||
					 !equalTupleDescs(olddesc, newdesc))
				ereport(ERROR,

/*
 * PrepareForTupleInvalidation
 *		Detect whether invalidation of this tuple implies invalidation
 *		of catalog/relation cache entries; if so, register inval events.
 */
static void
PrepareForTupleInvalidation(Relation relation, HeapTuple tuple)
{
	Oid			tupleRelId;
	Oid			databaseId;
	Oid			relationId;

	/* Do nothing during bootstrap */
	if (IsBootstrapProcessingMode())
		return;

	/*
	 * We only need to worry about invalidation for tuples that are in system
	 * relations; user-relation tuples are never in catcaches and can't affect
	 * the relcache either.
	 */
	if (!IsSystemRelation(relation))
		return;

	/*
	 * TOAST tuples can likewise be ignored here. Note that TOAST tables are
	 * considered system relations so they are not filtered by the above test.
	 */
	if (IsToastRelation(relation))
		return;

	/*
	 * First let the catcache do its thing
	 */
	PrepareToInvalidateCacheTuple(relation, tuple,
								  RegisterCatcacheInvalidation);

	/*
	 * Now, is this tuple one of the primary definers of a relcache entry?
	 */
	tupleRelId = RelationGetRelid(relation);

	if (tupleRelId == RelationRelationId)
	{
		Form_pg_class classtup = (Form_pg_class) GETSTRUCT(tuple);

		relationId = HeapTupleGetOid(tuple);
		if (classtup->relisshared)
			databaseId = InvalidOid;
		else
			databaseId = MyDatabaseId;
	}
	else if (tupleRelId == AttributeRelationId)
	{
		Form_pg_attribute atttup = (Form_pg_attribute) GETSTRUCT(tuple);

		relationId = atttup->attrelid;

		/*
		 * KLUGE ALERT: we always send the relcache event with MyDatabaseId,
		 * even if the rel in question is shared (which we can't easily tell).
		 * This essentially means that only backends in this same database
		 * will react to the relcache flush request.  This is in fact
		 * appropriate, since only those backends could see our pg_attribute
		 * change anyway.  It looks a bit ugly though.	(In practice, shared
		 * relations can't have schema changes after bootstrap, so we should
		 * never come here for a shared rel anyway.)
		 */
		databaseId = MyDatabaseId;
	}
	else if (tupleRelId == IndexRelationId)
	{
		Form_pg_index indextup = (Form_pg_index) GETSTRUCT(tuple);

		/*
		 * When a pg_index row is updated, we should send out a relcache inval
		 * for the index relation.	As above, we don't know the shared status
		 * of the index, but in practice it doesn't matter since indexes of
		 * shared catalogs can't have such updates.
		 */
		relationId = indextup->indexrelid;
		databaseId = MyDatabaseId;
	}
	else
		return;

	/*
	 * Yes.  We need to register a relcache invalidation event.
	 */
	RegisterRelcacheInvalidation(databaseId, relationId);
}

/*
 * Determine whether a relation can be proven functionally dependent on
 * a set of grouping columns.  If so, return TRUE and add the pg_constraint
 * OIDs of the constraints needed for the proof to the *constraintDeps list.
 *
 * grouping_columns is a list of grouping expressions, in which columns of
 * the rel of interest are Vars with the indicated varno/varlevelsup.
 *
 * Currently we only check to see if the rel has a primary key that is a
 * subset of the grouping_columns.	We could also use plain unique constraints
 * if all their columns are known not null, but there's a problem: we need
 * to be able to represent the not-null-ness as part of the constraints added
 * to *constraintDeps.	FIXME whenever not-null constraints get represented
 * in pg_constraint.
 */
bool
check_functional_grouping(Oid relid,
						  Index varno, Index varlevelsup,
						  List *grouping_columns,
						  List **constraintDeps)
{
	bool		result = false;
	Relation	pg_constraint;
	HeapTuple	tuple;
	SysScanDesc scan;
	ScanKeyData skey[1];

	/* Scan pg_constraint for constraints of the target rel */
	pg_constraint = heap_open(ConstraintRelationId, AccessShareLock);

	ScanKeyInit(&skey[0],
				Anum_pg_constraint_conrelid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(relid));

	scan = systable_beginscan(pg_constraint, ConstraintRelidIndexId, true,
							  SnapshotNow, 1, skey);

	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
	{
		Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
		Datum		adatum;
		bool		isNull;
		ArrayType  *arr;
		int16	   *attnums;
		int			numkeys;
		int			i;
		bool		found_col;

		/* Only PK constraints are of interest for now, see comment above */
		if (con->contype != CONSTRAINT_PRIMARY)
			continue;
		/* Constraint must be non-deferrable */
		if (con->condeferrable)
			continue;

		/* Extract the conkey array, ie, attnums of PK's columns */
		adatum = heap_getattr(tuple, Anum_pg_constraint_conkey,
							  RelationGetDescr(pg_constraint), &isNull);
		if (isNull)
			elog(ERROR, "null conkey for constraint %u",
				 HeapTupleGetOid(tuple));
		arr = DatumGetArrayTypeP(adatum);		/* ensure not toasted */
		numkeys = ARR_DIMS(arr)[0];
		if (ARR_NDIM(arr) != 1 ||
			numkeys < 0 ||
			ARR_HASNULL(arr) ||
			ARR_ELEMTYPE(arr) != INT2OID)
			elog(ERROR, "conkey is not a 1-D smallint array");
		attnums = (int16 *) ARR_DATA_PTR(arr);

		found_col = false;
		for (i = 0; i < numkeys; i++)
		{
			AttrNumber	attnum = attnums[i];
			ListCell   *gl;

			found_col = false;
			foreach(gl, grouping_columns)
			{
				Var		   *gvar = (Var *) lfirst(gl);

				if (IsA(gvar, Var) &&
					gvar->varno == varno &&
					gvar->varlevelsup == varlevelsup &&
					gvar->varattno == attnum)
				{
					found_col = true;
					break;
				}
			}
			if (!found_col)
				break;
		}

		if (found_col)
		{
			/* The PK is a subset of grouping_columns, so we win */
			*constraintDeps = lappend_oid(*constraintDeps,
										  HeapTupleGetOid(tuple));
//.........这里部分代码省略.........

//.........这里部分代码省略.........
	key.reltablespace = reltablespace;
	key.relfilenode = relfilenode;

	/*
	 * Check cache and return entry if one is found. Even if no target
	 * relation can be found later on we store the negative match and return a
	 * InvalidOid from cache. That's not really necessary for performance
	 * since querying invalid values isn't supposed to be a frequent thing,
	 * but it's basically free.
	 */
	entry = hash_search(RelfilenodeMapHash, (void *) &key, HASH_FIND, &found);

	if (found)
		return entry->relid;

	/* ok, no previous cache entry, do it the hard way */

	/* initialize empty/negative cache entry before doing the actual lookups */
	relid = InvalidOid;

	if (reltablespace == GLOBALTABLESPACE_OID)
	{
		/*
		 * Ok, shared table, check relmapper.
		 */
		relid = RelationMapFilenodeToOid(relfilenode, true);
	}
	else
	{
		/*
		 * Not a shared table, could either be a plain relation or a
		 * non-shared, nailed one, like e.g. pg_class.
		 */

		/* check for plain relations by looking in pg_class */
		relation = heap_open(RelationRelationId, AccessShareLock);

		/* copy scankey to local copy, it will be modified during the scan */
		memcpy(skey, relfilenode_skey, sizeof(skey));

		/* set scan arguments */
		skey[0].sk_argument = ObjectIdGetDatum(reltablespace);
		skey[1].sk_argument = ObjectIdGetDatum(relfilenode);

		scandesc = systable_beginscan(relation,
									  ClassTblspcRelfilenodeIndexId,
									  true,
									  NULL,
									  2,
									  skey);

		found = false;

		while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
		{
			if (found)
				elog(ERROR,
					 "unexpected duplicate for tablespace %u, relfilenode %u",
					 reltablespace, relfilenode);
			found = true;

#ifdef USE_ASSERT_CHECKING
			{
				bool		isnull;
				Oid			check;

				check = fastgetattr(ntp, Anum_pg_class_reltablespace,
									RelationGetDescr(relation),
									&isnull);
				Assert(!isnull && check == reltablespace);

				check = fastgetattr(ntp, Anum_pg_class_relfilenode,
									RelationGetDescr(relation),
									&isnull);
				Assert(!isnull && check == relfilenode);
			}
#endif
			relid = HeapTupleGetOid(ntp);
		}

		systable_endscan(scandesc);
		heap_close(relation, AccessShareLock);

		/* check for tables that are mapped but not shared */
		if (!found)
			relid = RelationMapFilenodeToOid(relfilenode, false);
	}

	/*
	 * Only enter entry into cache now, our opening of pg_class could have
	 * caused cache invalidations to be executed which would have deleted a
	 * new entry if we had entered it above.
	 */
	entry = hash_search(RelfilenodeMapHash, (void *) &key, HASH_ENTER, &found);
	if (found)
		elog(ERROR, "corrupted hashtable");
	entry->relid = relid;

	return relid;
}

/*
 * regoperin		- converts "oprname" to operator OID
 *
 * We also accept a numeric OID, for symmetry with the output routine.
 *
 * '0' signifies unknown (OID 0).  In all other cases, the input must
 * match an existing pg_operator entry.
 */
Datum
regoperin(PG_FUNCTION_ARGS)
{
	char	   *opr_name_or_oid = PG_GETARG_CSTRING(0);
	Oid			result = InvalidOid;
	List	   *names;
	FuncCandidateList clist;

	/* '0' ? */
	if (strcmp(opr_name_or_oid, "0") == 0)
		PG_RETURN_OID(InvalidOid);

	/* Numeric OID? */
	if (opr_name_or_oid[0] >= '0' &&
		opr_name_or_oid[0] <= '9' &&
		strspn(opr_name_or_oid, "0123456789") == strlen(opr_name_or_oid))
	{
		result = DatumGetObjectId(DirectFunctionCall1(oidin,
										  CStringGetDatum(opr_name_or_oid)));
		PG_RETURN_OID(result);
	}

	/* Else it's a name, possibly schema-qualified */

	/*
	 * In bootstrap mode we assume the given name is not schema-qualified, and
	 * just search pg_operator for a unique match.	This is needed for
	 * initializing other system catalogs (pg_namespace may not exist yet, and
	 * certainly there are no schemas other than pg_catalog).
	 */
	if (IsBootstrapProcessingMode())
	{
		int			matches = 0;
		Relation	hdesc;
		ScanKeyData skey[1];
		SysScanDesc sysscan;
		HeapTuple	tuple;

		ScanKeyInit(&skey[0],
					Anum_pg_operator_oprname,
					BTEqualStrategyNumber, F_NAMEEQ,
					CStringGetDatum(opr_name_or_oid));

		hdesc = heap_open(OperatorRelationId, AccessShareLock);
		sysscan = systable_beginscan(hdesc, OperatorNameNspIndexId, true,
									 SnapshotNow, 1, skey);

		while (HeapTupleIsValid(tuple = systable_getnext(sysscan)))
		{
			result = HeapTupleGetOid(tuple);
			if (++matches > 1)
				break;
		}

		systable_endscan(sysscan);
		heap_close(hdesc, AccessShareLock);

		if (matches == 0)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_FUNCTION),
					 errmsg("operator does not exist: %s", opr_name_or_oid)));
		else if (matches > 1)
			ereport(ERROR,
					(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
					 errmsg("more than one operator named %s",
							opr_name_or_oid)));

		PG_RETURN_OID(result);
	}

	/*
	 * Normal case: parse the name into components and see if it matches any
	 * pg_operator entries in the current search path.
	 */
	names = stringToQualifiedNameList(opr_name_or_oid);
	clist = OpernameGetCandidates(names, '\0');

	if (clist == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("operator does not exist: %s", opr_name_or_oid)));
	else if (clist->next != NULL)
		ereport(ERROR,
				(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
				 errmsg("more than one operator named %s",
						opr_name_or_oid)));

	result = clist->oid;

	PG_RETURN_OID(result);
}

/* given operator tuple, return the operator OID */
Oid
oprid(Operator op)
{
	return HeapTupleGetOid(op);
}

//.........这里部分代码省略.........

		/* report this backend in the PgBackendStatus array */
		pgstat_bestart();

		/* close the transaction we started above */
		CommitTransactionCommand();

		return;
	}

	/*
	 * Set up the global variables holding database id and default tablespace.
	 * But note we won't actually try to touch the database just yet.
	 *
	 * We take a shortcut in the bootstrap case, otherwise we have to look up
	 * the db's entry in pg_database.
	 */
	if (bootstrap)
	{
		MyDatabaseId = TemplateDbOid;
		MyDatabaseTableSpace = DEFAULTTABLESPACE_OID;
	}
	else if (in_dbname != NULL)
	{
		HeapTuple	tuple;
		Form_pg_database dbform;

		tuple = GetDatabaseTuple(in_dbname);
		if (!HeapTupleIsValid(tuple))
			ereport(FATAL,
					(errcode(ERRCODE_UNDEFINED_DATABASE),
					 errmsg("database \"%s\" does not exist", in_dbname)));
		dbform = (Form_pg_database) GETSTRUCT(tuple);
		MyDatabaseId = HeapTupleGetOid(tuple);
		MyDatabaseTableSpace = dbform->dattablespace;
		/* take database name from the caller, just for paranoia */
		strlcpy(dbname, in_dbname, sizeof(dbname));
	}
	else
	{
		/* caller specified database by OID */
		HeapTuple	tuple;
		Form_pg_database dbform;

		tuple = GetDatabaseTupleByOid(dboid);
		if (!HeapTupleIsValid(tuple))
			ereport(FATAL,
					(errcode(ERRCODE_UNDEFINED_DATABASE),
					 errmsg("database %u does not exist", dboid)));
		dbform = (Form_pg_database) GETSTRUCT(tuple);
		MyDatabaseId = HeapTupleGetOid(tuple);
		MyDatabaseTableSpace = dbform->dattablespace;
		Assert(MyDatabaseId == dboid);
		strlcpy(dbname, NameStr(dbform->datname), sizeof(dbname));
		/* pass the database name back to the caller */
		if (out_dbname)
			strcpy(out_dbname, dbname);
	}

	/*
	 * Now, take a writer's lock on the database we are trying to connect to.
	 * If there is a concurrently running DROP DATABASE on that database, this
	 * will block us until it finishes (and has committed its update of
	 * pg_database).
	 *
	 * Note that the lock is not held long, only until the end of this startup

/*
 * Guts of language creation.
 */
static void
create_proc_lang(const char *languageName, bool replace,
				 Oid languageOwner, Oid handlerOid, Oid inlineOid,
				 Oid valOid, bool trusted)
{
	Relation	rel;
	TupleDesc	tupDesc;
	Datum		values[Natts_pg_language];
	bool		nulls[Natts_pg_language];
	bool		replaces[Natts_pg_language];
	NameData	langname;
	HeapTuple	oldtup;
	HeapTuple	tup;
	bool		is_update;
	ObjectAddress myself,
				referenced;

	rel = heap_open(LanguageRelationId, RowExclusiveLock);
	tupDesc = RelationGetDescr(rel);

	/* Prepare data to be inserted */
	memset(values, 0, sizeof(values));
	memset(nulls, false, sizeof(nulls));
	memset(replaces, true, sizeof(replaces));

	namestrcpy(&langname, languageName);
	values[Anum_pg_language_lanname - 1] = NameGetDatum(&langname);
	values[Anum_pg_language_lanowner - 1] = ObjectIdGetDatum(languageOwner);
	values[Anum_pg_language_lanispl - 1] = BoolGetDatum(true);
	values[Anum_pg_language_lanpltrusted - 1] = BoolGetDatum(trusted);
	values[Anum_pg_language_lanplcallfoid - 1] = ObjectIdGetDatum(handlerOid);
	values[Anum_pg_language_laninline - 1] = ObjectIdGetDatum(inlineOid);
	values[Anum_pg_language_lanvalidator - 1] = ObjectIdGetDatum(valOid);
	nulls[Anum_pg_language_lanacl - 1] = true;

	/* Check for pre-existing definition */
	oldtup = SearchSysCache1(LANGNAME, PointerGetDatum(languageName));

	if (HeapTupleIsValid(oldtup))
	{
		/* There is one; okay to replace it? */
		if (!replace)
			ereport(ERROR,
					(errcode(ERRCODE_DUPLICATE_OBJECT),
					 errmsg("language \"%s\" already exists", languageName)));
		if (!pg_language_ownercheck(HeapTupleGetOid(oldtup), languageOwner))
			aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_LANGUAGE,
						   languageName);

		/*
		 * Do not change existing ownership or permissions.  Note
		 * dependency-update code below has to agree with this decision.
		 */
		replaces[Anum_pg_language_lanowner - 1] = false;
		replaces[Anum_pg_language_lanacl - 1] = false;

		/* Okay, do it... */
		tup = heap_modify_tuple(oldtup, tupDesc, values, nulls, replaces);
		simple_heap_update(rel, &tup->t_self, tup);

		ReleaseSysCache(oldtup);
		is_update = true;
	}
	else
	{
		/* Creating a new language */
		tup = heap_form_tuple(tupDesc, values, nulls);
		simple_heap_insert(rel, tup);
		is_update = false;
	}

	/* Need to update indexes for either the insert or update case */
	CatalogUpdateIndexes(rel, tup);

	/*
	 * Create dependencies for the new language.  If we are updating an
	 * existing language, first delete any existing pg_depend entries.
	 * (However, since we are not changing ownership or permissions, the
	 * shared dependencies do *not* need to change, and we leave them alone.)
	 */
	myself.classId = LanguageRelationId;
	myself.objectId = HeapTupleGetOid(tup);
	myself.objectSubId = 0;

	if (is_update)
		deleteDependencyRecordsFor(myself.classId, myself.objectId, true);

	/* dependency on owner of language */
	if (!is_update)
		recordDependencyOnOwner(myself.classId, myself.objectId,
								languageOwner);

	/* dependency on extension */
	recordDependencyOnCurrentExtension(&myself, is_update);

	/* dependency on the PL handler function */
	referenced.classId = ProcedureRelationId;
//.........这里部分代码省略.........

//.........这里部分代码省略.........
							  ObjectIdGetDatum(typeNamespace));
	if (HeapTupleIsValid(tup))
	{
		/*
		 * check that the type is not already defined.  It may exist as a
		 * shell type, however.
		 */
		if (((Form_pg_type) GETSTRUCT(tup))->typisdefined)
			ereport(ERROR,
					(errcode(ERRCODE_DUPLICATE_OBJECT),
					 errmsg("type \"%s\" already exists", typeName)));

		/*
		 * shell type must have been created by same owner
		 */
		if (((Form_pg_type) GETSTRUCT(tup))->typowner != ownerId)
			aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_TYPE, typeName);

		/* trouble if caller wanted to force the OID */
		if (OidIsValid(newTypeOid))
			elog(ERROR, "cannot assign new OID to existing shell type");

		/*
		 * Okay to update existing shell type tuple
		 */
		tup = heap_modify_tuple(tup,
								RelationGetDescr(pg_type_desc),
								values,
								nulls,
								replaces);

		simple_heap_update(pg_type_desc, &tup->t_self, tup);

		typeObjectId = HeapTupleGetOid(tup);

		rebuildDeps = true;		/* get rid of shell type's dependencies */
	}
	else
	{
		tup = heap_form_tuple(RelationGetDescr(pg_type_desc),
							  values,
							  nulls);

		/* Force the OID if requested by caller */
		if (OidIsValid(newTypeOid))
			HeapTupleSetOid(tup, newTypeOid);
		/* Use binary-upgrade override for pg_type.oid, if supplied. */
		else if (IsBinaryUpgrade)
		{
			if (!OidIsValid(binary_upgrade_next_pg_type_oid))
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
						 errmsg("pg_type OID value not set when in binary upgrade mode")));

			HeapTupleSetOid(tup, binary_upgrade_next_pg_type_oid);
			binary_upgrade_next_pg_type_oid = InvalidOid;
		}
		/* else allow system to assign oid */

		typeObjectId = simple_heap_insert(pg_type_desc, tup);
	}

	/* Update indexes */
	CatalogUpdateIndexes(pg_type_desc, tup);

	/*

/*
 * Workhorse for AlterLanguageOwner variants
 */
static void
AlterLanguageOwner_internal(HeapTuple tup, Relation rel, Oid newOwnerId)
{
	Form_pg_language lanForm;

	lanForm = (Form_pg_language) GETSTRUCT(tup);

	/*
	 * If the new owner is the same as the existing owner, consider the
	 * command to have succeeded.  This is for dump restoration purposes.
	 */
	if (lanForm->lanowner != newOwnerId)
	{
		Datum		repl_val[Natts_pg_language];
		bool		repl_null[Natts_pg_language];
		bool		repl_repl[Natts_pg_language];
		Acl		   *newAcl;
		Datum		aclDatum;
		bool		isNull;
		HeapTuple	newtuple;

		/* Otherwise, must be owner of the existing object */
		if (!pg_language_ownercheck(HeapTupleGetOid(tup), GetUserId()))
			aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_LANGUAGE,
						   NameStr(lanForm->lanname));

		/* Must be able to become new owner */
		check_is_member_of_role(GetUserId(), newOwnerId);

		memset(repl_null, false, sizeof(repl_null));
		memset(repl_repl, false, sizeof(repl_repl));

		repl_repl[Anum_pg_language_lanowner - 1] = true;
		repl_val[Anum_pg_language_lanowner - 1] = ObjectIdGetDatum(newOwnerId);

		/*
		 * Determine the modified ACL for the new owner.  This is only
		 * necessary when the ACL is non-null.