Status PlanExecutor::pickBestPlan(YieldPolicy policy) {
invariant(_currentState == kUsable);
// For YIELD_AUTO, this will both set an auto yield policy on the PlanExecutor and
// register it to receive notifications.
this->setYieldPolicy(policy);
// First check if we need to do subplanning.
PlanStage* foundStage = getStageByType(_root.get(), STAGE_SUBPLAN);
if (foundStage) {
SubplanStage* subplan = static_cast<SubplanStage*>(foundStage);
return subplan->pickBestPlan(_yieldPolicy.get());
}
// If we didn't have to do subplanning, we might still have to do regular
// multi plan selection...
foundStage = getStageByType(_root.get(), STAGE_MULTI_PLAN);
if (foundStage) {
MultiPlanStage* mps = static_cast<MultiPlanStage*>(foundStage);
return mps->pickBestPlan(_yieldPolicy.get());
}
// ...or, we might have to run a plan from the cache for a trial period, falling back on
// regular planning if the cached plan performs poorly.
foundStage = getStageByType(_root.get(), STAGE_CACHED_PLAN);
if (foundStage) {
CachedPlanStage* cachedPlan = static_cast<CachedPlanStage*>(foundStage);
return cachedPlan->pickBestPlan(_yieldPolicy.get());
}
// Either we chose a plan, or no plan selection was required. In both cases,
// our work has been successfully completed.
return Status::OK();
}
Status PlanExecutor::pickBestPlan(YieldPolicy policy) {
// For YIELD_AUTO, this will both set an auto yield policy on the PlanExecutor and
// register it to receive notifications.
this->setYieldPolicy(policy);
// First check if we need to do subplanning.
PlanStage* foundStage = getStageByType(_root.get(), STAGE_SUBPLAN);
if (foundStage) {
SubplanStage* subplan = static_cast<SubplanStage*>(foundStage);
return subplan->pickBestPlan(_yieldPolicy.get());
}
// If we didn't have to do subplanning, we might still have to do regular
// multi plan selection.
foundStage = getStageByType(_root.get(), STAGE_MULTI_PLAN);
if (foundStage) {
MultiPlanStage* mps = static_cast<MultiPlanStage*>(foundStage);
return mps->pickBestPlan(_yieldPolicy.get());
}
// Either we chose a plan, or no plan selection was required. In both cases,
// our work has been successfully completed.
return Status::OK();
}
