More fixes for planner's handling of LATERAL.

Re-allow subquery pullup for LATERAL subqueries, except when the subquery
is below an outer join and contains lateral references to relations outside
that outer join.  If we pull up in such a case, we risk introducing lateral
cross-references into outer joins' ON quals, which is something the code is
entirely unprepared to cope with right now; and I'm not sure it'll ever be
worth coping with.

Support lateral refs in VALUES (this seems to be the only additional path
type that needs such support as a consequence of re-allowing subquery
pullup).

Put in a slightly hacky fix for joinpath.c's refusal to consider
parameterized join paths even when there cannot be any unparameterized
ones.  This was causing "could not devise a query plan for the given query"
failures in queries involving more than two FROM items.

Put in an even more hacky fix for distribute_qual_to_rels() being unhappy
with join quals that contain references to rels outside their syntactic
scope; which is to say, disable that test altogether.  Need to think about
how to preserve some sort of debugging cross-check here, while not
expending more cycles than befits a debugging cross-check.

Author: tglsfdc

src/backend/optimizer/path/allpaths.c

@@ -1210,15 +1210,33 @@ set_function_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
  * set_values_pathlist
  *		Build the (single) access path for a VALUES RTE
  *
- * There can be no need for a parameterized path here.	(Although the SQL
- * spec does allow LATERAL (VALUES (x)), the parser will transform that
- * into a subquery, so it doesn't end up here.)
+ * As with subqueries, a VALUES RTE's path might be parameterized due to
+ * LATERAL references, but that's inherent in the values expressions and
+ * not a result of pushing down join quals.
  */
 static void
 set_values_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
 {
+	Relids		required_outer;
+
+	/*
+	 * If it's a LATERAL RTE, it might contain some Vars of the current query
+	 * level, requiring it to be treated as parameterized.  (NB: even though
+	 * the parser never marks VALUES RTEs as LATERAL, they could be so marked
+	 * by now, as a result of subquery pullup.)
+	 */
+	if (rte->lateral)
+	{
+		required_outer = pull_varnos_of_level((Node *) rte->values_lists, 0);
+		/* Enforce convention that empty required_outer is exactly NULL */
+		if (bms_is_empty(required_outer))
+			required_outer = NULL;
+	}
+	else
+		required_outer = NULL;
+
 	/* Generate appropriate path */
-	add_path(rel, create_valuesscan_path(root, rel));
+	add_path(rel, create_valuesscan_path(root, rel, required_outer));
 
 	/* Select cheapest path (pretty easy in this case...) */
 	set_cheapest(rel);

src/backend/optimizer/path/costsize.c

@@ -1046,20 +1046,28 @@ cost_functionscan(Path *path, PlannerInfo *root,
 /*
  * cost_valuesscan
  *	  Determines and returns the cost of scanning a VALUES RTE.
+ *
+ * 'baserel' is the relation to be scanned
+ * 'param_info' is the ParamPathInfo if this is a parameterized path, else NULL
  */
 void
-cost_valuesscan(Path *path, PlannerInfo *root, RelOptInfo *baserel)
+cost_valuesscan(Path *path, PlannerInfo *root,
+				RelOptInfo *baserel, ParamPathInfo *param_info)
 {
 	Cost		startup_cost = 0;
 	Cost		run_cost = 0;
+	QualCost	qpqual_cost;
 	Cost		cpu_per_tuple;
 
 	/* Should only be applied to base relations that are values lists */
 	Assert(baserel->relid > 0);
 	Assert(baserel->rtekind == RTE_VALUES);
 
-	/* valuesscans are never parameterized */
-	path->rows = baserel->rows;
+	/* Mark the path with the correct row estimate */
+	if (param_info)
+		path->rows = param_info->ppi_rows;
+	else
+		path->rows = baserel->rows;
 
 	/*
 	 * For now, estimate list evaluation cost at one operator eval per list
@@ -1068,8 +1076,10 @@ cost_valuesscan(Path *path, PlannerInfo *root, RelOptInfo *baserel)
 	cpu_per_tuple = cpu_operator_cost;
 
 	/* Add scanning CPU costs */
-	startup_cost += baserel->baserestrictcost.startup;
-	cpu_per_tuple += cpu_tuple_cost + baserel->baserestrictcost.per_tuple;
+	get_restriction_qual_cost(root, baserel, param_info, &qpqual_cost);
+
+	startup_cost += qpqual_cost.startup;
+	cpu_per_tuple += cpu_tuple_cost + qpqual_cost.per_tuple;
 	run_cost += cpu_per_tuple * baserel->tuples;
 
 	path->startup_cost = startup_cost;

src/backend/optimizer/path/joinpath.c

@@ -147,6 +147,32 @@ add_paths_to_joinrel(PlannerInfo *root,
 													  sjinfo->min_lefthand));
 	}
 
+	/*
+	 * However, when a LATERAL subquery is involved, we have to be a bit
+	 * laxer, because there may simply not be any paths for the joinrel that
+	 * aren't parameterized by whatever the subquery is parameterized by.
+	 * Hence, add to param_source_rels anything that is in the minimum
+	 * parameterization of either input (and not in the other input).
+	 *
+	 * XXX need a more principled way of determining minimum parameterization.
+	 */
+	if (outerrel->cheapest_total_path == NULL)
+	{
+		Path	   *cheapest = (Path *) linitial(outerrel->cheapest_parameterized_paths);
+
+		param_source_rels = bms_join(param_source_rels,
+									 bms_difference(PATH_REQ_OUTER(cheapest),
+													innerrel->relids));
+	}
+	if (innerrel->cheapest_total_path == NULL)
+	{
+		Path	   *cheapest = (Path *) linitial(innerrel->cheapest_parameterized_paths);
+
+		param_source_rels = bms_join(param_source_rels,
+									 bms_difference(PATH_REQ_OUTER(cheapest),
+													outerrel->relids));
+	}
+
 	/*
 	 * 1. Consider mergejoin paths where both relations must be explicitly
 	 * sorted.	Skip this if we can't mergejoin.

src/backend/optimizer/plan/createplan.c

@@ -1713,20 +1713,32 @@ create_valuesscan_plan(PlannerInfo *root, Path *best_path,
 	ValuesScan *scan_plan;
 	Index		scan_relid = best_path->parent->relid;
 	RangeTblEntry *rte;
+	List	   *values_lists;
 
 	/* it should be a values base rel... */
 	Assert(scan_relid > 0);
 	rte = planner_rt_fetch(scan_relid, root);
 	Assert(rte->rtekind == RTE_VALUES);
+	values_lists = rte->values_lists;
 
 	/* Sort clauses into best execution order */
 	scan_clauses = order_qual_clauses(root, scan_clauses);
 
 	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
 	scan_clauses = extract_actual_clauses(scan_clauses, false);
 
+	/* Replace any outer-relation variables with nestloop params */
+	if (best_path->param_info)
+	{
+		scan_clauses = (List *)
+			replace_nestloop_params(root, (Node *) scan_clauses);
+		/* The values lists could contain nestloop params, too */
+		values_lists = (List *)
+			replace_nestloop_params(root, (Node *) values_lists);
+	}
+
 	scan_plan = make_valuesscan(tlist, scan_clauses, scan_relid,
-								rte->values_lists);
+								values_lists);
 
 	copy_path_costsize(&scan_plan->scan.plan, best_path);
 

src/backend/optimizer/plan/initsplan.c

@@ -232,6 +232,8 @@ extract_lateral_references(PlannerInfo *root, int rtindex)
 		vars = pull_vars_of_level((Node *) rte->subquery, 1);
 	else if (rte->rtekind == RTE_FUNCTION)
 		vars = pull_vars_of_level(rte->funcexpr, 0);
+	else if (rte->rtekind == RTE_VALUES)
+		vars = pull_vars_of_level((Node *) rte->values_lists, 0);
 	else
 		return;
 
@@ -874,9 +876,19 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
 	/*
 	 * Cross-check: clause should contain no relids not within its scope.
 	 * Otherwise the parser messed up.
+	 *
+	 * XXX temporarily disable the qualscope cross-check, which tends to
+	 * reject quals pulled up from LATERAL subqueries.  This is only in the
+	 * nature of a debugging crosscheck anyway.  I'm loath to remove it
+	 * permanently, but need to think a bit harder about how to replace it.
+	 * See also disabled Assert below.  (The ojscope test is still okay
+	 * because we prevent pullup of LATERAL subqueries that might cause it to
+	 * be violated.)
 	 */
+#ifdef NOT_USED
 	if (!bms_is_subset(relids, qualscope))
 		elog(ERROR, "JOIN qualification cannot refer to other relations");
+#endif
 	if (ojscope && !bms_is_subset(relids, ojscope))
 		elog(ERROR, "JOIN qualification cannot refer to other relations");
 
@@ -1031,7 +1043,9 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
 		if (outerjoin_delayed)
 		{
 			/* Should still be a subset of current scope ... */
+#ifdef NOT_USED					/* XXX temporarily disabled for LATERAL */
 			Assert(bms_is_subset(relids, qualscope));
+#endif
 
 			/*
 			 * Because application of the qual will be delayed by outer join,

src/backend/optimizer/plan/planner.c

@@ -334,7 +334,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
 	 * query.
 	 */
 	parse->jointree = (FromExpr *)
-		pull_up_subqueries(root, (Node *) parse->jointree, NULL, NULL);
+		pull_up_subqueries(root, (Node *) parse->jointree);
 
 	/*
 	 * If this is a simple UNION ALL query, flatten it into an appendrel. We