Function apply_map_update

src/backend/utils/cache/relmapper.c:325–349

* apply_map_update * * Insert a new mapping into the given map variable, replacing any existing * mapping for the same relation. * * In some cases the caller knows there must be an existing mapping; pass * add_okay = false to draw an error if not. */

 * add_okay = false to draw an error if not.
 */
static void
apply_map_update(RelMapFile *map, Oid relationId, Oid fileNode, bool add_okay)
{
	int32		i;

	/* Replace any existing mapping */
	for (i = 0; i < map->num_mappings; i++)
	{
		if (relationId == map->mappings[i].mapoid)
		{
			map->mappings[i].mapfilenode = fileNode;
			return;
		}
	}

	/* Nope, need to add a new mapping */
	if (!add_okay)
		elog(ERROR, "attempt to apply a mapping to unmapped relation %u",
			 relationId);
	if (map->num_mappings >= MAX_MAPPINGS)
		elog(ERROR, "ran out of space in relation map");
	map->mappings[map->num_mappings].mapoid = relationId;
	map->mappings[map->num_mappings].mapfilenode = fileNode;
	map->num_mappings++;
}

/*
 * merge_map_updates