bool MultiPlanRunner::pickBestPlan(size_t* out, BSONObj* objOut) {
static const int timesEachPlanIsWorked = 100;
// Run each plan some number of times.
for (int i = 0; i < timesEachPlanIsWorked; ++i) {
bool moreToDo = workAllPlans(objOut);
if (!moreToDo) { break; }
}
if (_failure || _killed) { return false; }
// After picking best plan, ranking will own plan stats from
// candidate solutions (winner and losers).
std::auto_ptr<PlanRankingDecision> ranking(new PlanRankingDecision);
size_t bestChild = PlanRanker::pickBestPlan(_candidates, ranking.get());
// Copy candidate order. We will need this to sort candidate stats for explain
// after transferring ownership of 'ranking' to plan cache.
std::vector<size_t> candidateOrder = ranking->candidateOrder;
// Run the best plan. Store it.
_bestPlan.reset(new PlanExecutor(_candidates[bestChild].ws,
_candidates[bestChild].root));
_bestPlan->setYieldPolicy(_policy);
_alreadyProduced = _candidates[bestChild].results;
_bestSolution.reset(_candidates[bestChild].solution);
QLOG() << "Winning solution:\n" << _bestSolution->toString() << endl;
size_t backupChild = bestChild;
if (_bestSolution->hasBlockingStage && (0 == _alreadyProduced.size())) {
QLOG() << "Winner has blocking stage, looking for backup plan...\n";
for (size_t i = 0; i < _candidates.size(); ++i) {
if (!_candidates[i].solution->hasBlockingStage) {
QLOG() << "Candidate " << i << " is backup child\n";
backupChild = i;
_backupSolution = _candidates[i].solution;
_backupAlreadyProduced = _candidates[i].results;
_backupPlan = new PlanExecutor(_candidates[i].ws, _candidates[i].root);
_backupPlan->setYieldPolicy(_policy);
break;
}
}
}
// Store the choice we just made in the cache. We do
// not cache the query if:
// 1) The query is of a type that is not safe to cache, or
// 2) the winning plan did not actually produce any results,
// without hitting EOF. In this case, we have no information to
// suggest that this plan is good.
const PlanStageStats* bestStats = ranking->stats.vector()[0];
if (PlanCache::shouldCacheQuery(*_query)
&& (!_alreadyProduced.empty() || bestStats->common.isEOF)) {
Database* db = cc().database();
verify(NULL != db);
Collection* collection = db->getCollection(_query->ns());
verify(NULL != collection);
PlanCache* cache = collection->infoCache()->getPlanCache();
// Create list of candidate solutions for the cache with
// the best solution at the front.
std::vector<QuerySolution*> solutions;
// Generate solutions and ranking decisions sorted by score.
for (size_t orderingIndex = 0;
orderingIndex < candidateOrder.size(); ++orderingIndex) {
// index into candidates/ranking
size_t i = candidateOrder[orderingIndex];
solutions.push_back(_candidates[i].solution);
}
// Check solution cache data. Do not add to cache if
// we have any invalid SolutionCacheData data.
// XXX: One known example is 2D queries
bool validSolutions = true;
for (size_t i = 0; i < solutions.size(); ++i) {
if (NULL == solutions[i]->cacheData.get()) {
QLOG() << "Not caching query because this solution has no cache data: "
<< solutions[i]->toString();
validSolutions = false;
break;
}
}
if (validSolutions) {
cache->add(*_query, solutions, ranking.release());
}
}
// Clear out the candidate plans, leaving only stats as we're all done w/them.
// Traverse candidate plans in order or score
for (size_t orderingIndex = 0;
orderingIndex < candidateOrder.size(); ++orderingIndex) {
// index into candidates/ranking
size_t i = candidateOrder[orderingIndex];
if (i == bestChild) { continue; }
if (i == backupChild) { continue; }
delete _candidates[i].solution;
// Remember the stats for the candidate plan because we always show it on an
// explain. (The {verbose:false} in explain() is client-side trick; we always
// generate a "verbose" explain.)
PlanStageStats* stats = _candidates[i].root->getStats();
if (stats) {
_candidateStats.push_back(stats);
}
delete _candidates[i].root;
// ws must die after the root.
delete _candidates[i].ws;
}
_candidates.clear();
if (NULL != out) { *out = bestChild; }
return true;
}
bool MultiPlanRunner::pickBestPlan(size_t* out) {
static const int timesEachPlanIsWorked = 100;
// Run each plan some number of times.
for (int i = 0; i < timesEachPlanIsWorked; ++i) {
bool moreToDo = workAllPlans();
if (!moreToDo) { break; }
}
if (_failure || _killed) { return false; }
auto_ptr<PlanRankingDecision> ranking(new PlanRankingDecision());
size_t bestChild = PlanRanker::pickBestPlan(_candidates, ranking.get());
// Run the best plan. Store it.
_bestPlan.reset(new PlanExecutor(_candidates[bestChild].ws,
_candidates[bestChild].root));
_bestPlan->setYieldPolicy(_policy);
_alreadyProduced = _candidates[bestChild].results;
_bestSolution.reset(_candidates[bestChild].solution);
QLOG() << "Winning solution:\n" << _bestSolution->toString() << endl;
size_t backupChild = bestChild;
if (_bestSolution->hasSortStage && (0 == _alreadyProduced.size())) {
QLOG() << "Winner has blocked sort, looking for backup plan...\n";
for (size_t i = 0; i < _candidates.size(); ++i) {
if (!_candidates[i].solution->hasSortStage) {
QLOG() << "Candidate " << i << " is backup child\n";
backupChild = i;
_backupSolution = _candidates[i].solution;
_backupAlreadyProduced = _candidates[i].results;
_backupPlan = new PlanExecutor(_candidates[i].ws, _candidates[i].root);
_backupPlan->setYieldPolicy(_policy);
break;
}
}
}
// Store the choice we just made in the cache.
if (PlanCache::shouldCacheQuery(*_query)) {
Database* db = cc().database();
verify(NULL != db);
Collection* collection = db->getCollection(_query->ns());
verify(NULL != collection);
PlanCache* cache = collection->infoCache()->getPlanCache();
// Create list of candidate solutions for the cache with
// the best solution at the front.
std::vector<QuerySolution*> solutions;
solutions.push_back(_bestSolution.get());
for (size_t i = 0; i < _candidates.size(); ++i) {
if (i == bestChild) { continue; }
solutions.push_back(_candidates[i].solution);
}
// Check solution cache data. Do not add to cache if
// we have any invalid SolutionCacheData data.
// XXX: One known example is 2D queries
bool validSolutions = true;
for (size_t i = 0; i < solutions.size(); ++i) {
if (NULL == solutions[i]->cacheData.get()) {
QLOG() << "Not caching query because this solution has no cache data: "
<< solutions[i]->toString();
validSolutions = false;
break;
}
}
if (validSolutions) {
cache->add(*_query, solutions, ranking.release());
}
}
// Clear out the candidate plans, leaving only stats as we're all done w/them.
for (size_t i = 0; i < _candidates.size(); ++i) {
if (i == bestChild) { continue; }
if (i == backupChild) { continue; }
delete _candidates[i].solution;
// Remember the stats for the candidate plan because we always show it on an
// explain. (The {verbose:false} in explain() is client-side trick; we always
// generate a "verbose" explain.)
PlanStageStats* stats = _candidates[i].root->getStats();
if (stats) {
_candidateStats.push_back(stats);
}
delete _candidates[i].root;
// ws must die after the root.
delete _candidates[i].ws;
}
_candidates.clear();
if (NULL != out) { *out = bestChild; }
return true;
}