Function ExecReScanSetParamPlan

src/backend/executor/nodeSubplan.c:1512–1550

* Mark an initplan as needing recalculation */

 * Mark an initplan as needing recalculation
 */
void
ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
{
	PlanState  *planstate = node->planstate;
	SubPlan    *subplan = node->subplan;
	EState	   *estate = parent->state;
	ListCell   *l;

	/* sanity checks */
	if (subplan->parParam != NIL)
		elog(ERROR, "direct correlated subquery unsupported as initplan");
	if (subplan->setParam == NIL)
		elog(ERROR, "setParam list of initplan is empty");
	if (bms_is_empty(planstate->plan->extParam))
		elog(ERROR, "extParam set of initplan is empty");

	/*
	 * Don't actually re-scan: it'll happen inside ExecSetParamPlan if needed.
	 */

	/*
	 * Mark this subplan's output parameters as needing recalculation.
	 *
	 * CTE subplans are never executed via parameter recalculation; instead
	 * they get run when called by nodeCtescan.c.  So don't mark the output
	 * parameter of a CTE subplan as dirty, but do set the chgParam bit for it
	 * so that dependent plan nodes will get told to rescan.
	 */
	foreach(l, subplan->setParam)
	{
		int			paramid = lfirst_int(l);
		ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);

		if (subplan->subLinkType != CTE_SUBLINK)
			prm->execPlan = node;

		parent->chgParam = bms_add_member(parent->chgParam, paramid);
	}
}