Function SetRelationHasSubclass

src/backend/commands/tablecmds.c:3890–3919

* SetRelationHasSubclass * Set the value of the relation's relhassubclass field in pg_class. * * NOTE: caller must be holding an appropriate lock on the relation. * ShareUpdateExclusiveLock is sufficient. * * NOTE: an important side-effect of this operation is that an SI invalidation * message is sent out to all backends --- including me --- causing plans * referencing the relation to be

 * row.
 */
void
SetRelationHasSubclass(Oid relationId, bool relhassubclass)
{
	Relation	relationRelation;
	HeapTuple	tuple;
	Form_pg_class classtuple;

	/*
	 * Fetch a modifiable copy of the tuple, modify it, update pg_class.
	 */
	relationRelation = table_open(RelationRelationId, RowExclusiveLock);
	tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relationId));
	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "cache lookup failed for relation %u", relationId);
	classtuple = (Form_pg_class) GETSTRUCT(tuple);

	if (classtuple->relhassubclass != relhassubclass)
	{
		classtuple->relhassubclass = relhassubclass;
		CatalogTupleUpdate(relationRelation, &tuple->t_self, tuple);
	}
	else
	{
		/* no need to change tuple, but force relcache rebuild anyway */
		CacheInvalidateRelcacheByTuple(tuple);
	}

	heap_freetuple(tuple);
	table_close(relationRelation, RowExclusiveLock);
}

/*
 * CheckRelationTableSpaceMove