Function create_sort_path

src/backend/optimizer/util/pathnode.c:4882–4918

* create_sort_path * Creates a pathnode that represents performing an explicit sort. * * 'rel' is the parent relation associated with the result * 'subpath' is the path representing the source of data * 'pathkeys' represents the desired sort order * 'limit_tuples' is the estimated bound on the number of output tuples, * or -1 if no LIMIT or couldn't estimate */

 *		or -1 if no LIMIT or couldn't estimate
 */
SortPath *
create_sort_path(PlannerInfo *root,
				 RelOptInfo *rel,
				 Path *subpath,
				 List *pathkeys,
				 double limit_tuples)
{
	SortPath   *pathnode = makeNode(SortPath);

	Assert(pathkeys != NIL);

	pathnode->path.pathtype = T_Sort;
	pathnode->path.parent = rel;
	/* Sort doesn't project, so use source path's pathtarget */
	pathnode->path.pathtarget = subpath->pathtarget;
	/* For now, assume we are above any joins, so no parameterization */
	pathnode->path.param_info = NULL;
	pathnode->path.parallel_aware = false;
	pathnode->path.parallel_safe = rel->consider_parallel &&
		subpath->parallel_safe;
	pathnode->path.parallel_workers = subpath->parallel_workers;
	pathnode->path.pathkeys = pathkeys;
	pathnode->path.locus = subpath->locus;
	pathnode->path.motionHazard = subpath->motionHazard;
	pathnode->path.barrierHazard = subpath->barrierHazard;

	pathnode->subpath = subpath;

	cost_sort(&pathnode->path, root, pathkeys,
			  subpath->total_cost,
			  subpath->rows,
			  subpath->pathtarget->width,
			  0.0,				/* XXX comparison_cost shouldn't be 0? */
			  work_mem, limit_tuples);

	return pathnode;
}

#ifdef NOT_USED /* Group nodes are not used in GPDB */
/*