planner: introduce a flag to cost calculation to control some behavio…

…rs (pingcap#34499)

ref pingcap#33945

planner/core/common_plans.go

@@ -1536,7 +1536,7 @@ func (e *Explain) getOperatorInfo(p Plan, id string) (string, string, string, st
 	estCost := "N/A"
 	if pp, ok := p.(PhysicalPlan); ok {
 		if p.SCtx().GetSessionVars().EnableNewCostInterface {
-			planCost, _ := pp.GetPlanCost(property.RootTaskType)
+			planCost, _ := pp.GetPlanCost(property.RootTaskType, 0)
 			estCost = strconv.FormatFloat(planCost, 'f', 2, 64)
 		} else {
 			estCost = strconv.FormatFloat(pp.Cost(), 'f', 2, 64)

planner/core/find_best_task.go

@@ -319,7 +319,7 @@ func getTaskPlanCost(t task) (float64, error) {
 	default:
 		return 0, errors.New("unknown task type")
 	}
-	return t.plan().GetPlanCost(taskType)
+	return t.plan().GetPlanCost(taskType, 0)
 }
 
 type physicalOptimizeOp struct {

planner/core/plan.go

@@ -319,7 +319,7 @@ type PhysicalPlan interface {
 	Plan
 
 	// GetPlanCost calculates the cost of the plan if it has not been calculated yet and returns the cost.
-	GetPlanCost(taskType property.TaskType) (float64, error)
+	GetPlanCost(taskType property.TaskType, costFlag uint64) (float64, error)
 
 	// attach2Task makes the current physical plan as the father of task's physicalPlan and updates the cost of
 	// current task. If the child's task is cop task, some operator may close this task and return a new rootTask.