Function create_partial_bitmap_paths

src/backend/optimizer/path/allpaths.c:4652–4678

* create_partial_bitmap_paths * Build partial bitmap heap path for the relation */

 *	  Build partial bitmap heap path for the relation
 */
void
create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel,
							Path *bitmapqual)
{
	int			parallel_workers;
	double		pages_fetched;

	/* Compute heap pages for bitmap heap scan */
	pages_fetched = compute_bitmap_pages(root, rel, bitmapqual, 1.0,
										 NULL, NULL);


	/*
	 * Don't support parallel BitmapScan for AO/AOCS.
	 */
	if (rel->reloptkind == RELOPT_BASEREL && (AMHandlerIsAO(rel->amhandler)))
		return;

	parallel_workers = compute_parallel_worker(root, rel, pages_fetched, -1,
											   max_parallel_workers_per_gather);

	if (parallel_workers <= 1)
		return;

	add_partial_path(rel, (Path *) create_bitmap_heap_path(root, rel,
														   bitmapqual, rel->lateral_relids, 1.0, parallel_workers));
}

/*
 * Compute the number of parallel workers that should be used to scan a