Function fix_upper_expr

src/backend/optimizer/plan/setrefs.c:3533–3549

* fix_upper_expr * Modifies an expression tree so that all Var nodes reference outputs * of a subplan. Also looks for Aggref nodes that should be replaced * by initplan output Params. Also performs opcode lookup, and adds * regclass OIDs to root->glob->relationOids. * * This is used to fix up target and qual expressions of non-join upper-level * plan nodes, as well as index-only scan

 * The original tree is not modified.
 */
static Node *
fix_upper_expr(PlannerInfo *root,
			   Node *node,
			   indexed_tlist *subplan_itlist,
			   Index newvarno,
			   int rtoffset,
			   double num_exec)
{
	fix_upper_expr_context context;

	context.root = root;
	context.subplan_itlist = subplan_itlist;
	context.newvarno = newvarno;
	context.rtoffset = rtoffset;
	context.num_exec = num_exec;
	return fix_upper_expr_mutator(node, &context);
}

static Node *
fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context)