Function attrMap

src/backend/executor/execMain.c:4156–4171

Use the given attribute map to convert an attribute number in the * base relation to an attribute number in the other relation. Forgive * out-of-range attributes by mapping them to zero. Treat null as * the identity map. */

 * the identity map.
 */
AttrNumber
attrMap(TupleConversionMap *map, AttrNumber anum)
{
	if (map == NULL)
		return anum;

	if (0 < anum && anum <= map->indesc->natts)
	{
		for (int i = 0; i < map->outdesc->natts; i++)
		{
			if (map->attrMap->attnums[i] == anum)
				return i + 1;
		}
	}
	return 0;
}

/* For attrMapExpr below.
 *