Function create_memoize_path

src/backend/optimizer/util/pathnode.c:2276–2321

* create_memoize_path * Creates a path corresponding to a Memoize plan, returning the pathnode. */

 *	  Creates a path corresponding to a Memoize plan, returning the pathnode.
 */
MemoizePath *
create_memoize_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath,
					List *param_exprs, List *hash_operators,
					bool singlerow, bool binary_mode, double calls)
{
	MemoizePath *pathnode = makeNode(MemoizePath);

	Assert(subpath->parent == rel);

	pathnode->path.pathtype = T_Memoize;
	pathnode->path.parent = rel;
	pathnode->path.pathtarget = rel->reltarget;
	pathnode->path.param_info = subpath->param_info;
	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 = subpath->pathkeys;
	pathnode->path.rescannable = subpath->rescannable;

	pathnode->path.locus = subpath->locus;
	pathnode->subpath = subpath;
	pathnode->hash_operators = hash_operators;
	pathnode->param_exprs = param_exprs;
	pathnode->singlerow = singlerow;
	pathnode->binary_mode = binary_mode;
	pathnode->calls = calls;

	/*
	 * For now we set est_entries to 0.  cost_memoize_rescan() does all the
	 * hard work to determine how many cache entries there are likely to be,
	 * so it seems best to leave it up to that function to fill this field in.
	 * If left at 0, the executor will make a guess at a good value.
	 */
	pathnode->est_entries = 0;

	/*
	 * Add a small additional charge for caching the first entry.  All the
	 * harder calculations for rescans are performed in cost_memoize_rescan().
	 */
	pathnode->path.startup_cost = subpath->startup_cost + cpu_tuple_cost;
	pathnode->path.total_cost = subpath->total_cost + cpu_tuple_cost;
	pathnode->path.rows = subpath->rows;

	return pathnode;
}

/*
 * create_unique_path