Function set_cte_pathlist

src/backend/optimizer/path/allpaths.c:2908–3178

* set_cte_pathlist * Build the (single) access path for a non-self-reference CTE RTE * * There's no need for a separate set_cte_size phase, since we don't * support join-qual-parameterized paths for CTEs. */

 * support join-qual-parameterized paths for CTEs.
 */
static void
set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
{
	PlannerInfo *cteroot;
	Index		levelsup;
	int			ndx;
	ListCell   *lc;
	int			planinfo_id;
	CommonTableExpr *cte = NULL;
	double		tuple_fraction = 0.0;
	CtePlanInfo *cteplaninfo;
	List	   *pathkeys = NULL;
	PlannerInfo *subroot = NULL;
	RelOptInfo *sub_final_rel;
	Relids		required_outer;
	bool		is_shared;
	Query           *subquery = NULL;
	bool            contain_volatile_function = false;

	/*
	 * Find the referenced CTE based on the given range table entry
	 */
	levelsup = rte->ctelevelsup;
	cteroot = root;
	while (levelsup-- > 0)
	{
		cteroot = cteroot->parent_root;
		if (!cteroot)			/* shouldn't happen */
			elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
	}

	ndx = 0;
	foreach(lc, cteroot->parse->cteList)
	{
		cte = (CommonTableExpr *) lfirst(lc);

		if (strcmp(cte->ctename, rte->ctename) == 0)
			break;
		ndx++;
	}
	if (lc == NULL)				/* shouldn't happen */
		elog(ERROR, "could not find CTE \"%s\"", rte->ctename);

	Assert(IsA(cte->ctequery, Query));
	/*
	 * Copy query node since subquery_planner may trash it, and we need it
	 * intact in case we need to create another plan for the CTE
	 */
	subquery = (Query *) copyObject(cte->ctequery);
	contain_volatile_function = contain_volatile_functions((Node *) subquery);

	/*
	 * In PostgreSQL, we use the index to look up the plan ID in the
	 * cteroot->cte_plan_ids list. In GPDB, CTE plans work differently, and
	 * we look up the CtePlanInfo struct in the list_cteplaninfo instead.
	 */
	planinfo_id = ndx;