Function create_incremental_sort_path

src/backend/optimizer/util/pathnode.c:4832–4870

* create_incremental_sort_path * Creates a pathnode that represents performing an incremental 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 * 'presorted_keys' is the number of keys by which the input path is * already sorted * 'limit_tuples' is the estimated bound o

 *		or -1 if no LIMIT or couldn't estimate
 */
IncrementalSortPath *
create_incremental_sort_path(PlannerInfo *root,
							 RelOptInfo *rel,
							 Path *subpath,
							 List *pathkeys,
							 int presorted_keys,
							 double limit_tuples)
{
	IncrementalSortPath *sort = makeNode(IncrementalSortPath);
	SortPath   *pathnode = &sort->spath;

	pathnode->path.pathtype = T_IncrementalSort;
	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->subpath = subpath;
	pathnode->path.locus = subpath->locus;

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

	sort->nPresortedCols = presorted_keys;

	return sort;
}

/*
 * create_sort_path