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/**
* Copyright (C) 2020-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/query/sbe_multi_planner.h"
#include "mongo/db/exec/multi_plan.h"
#include "mongo/db/exec/sbe/expressions/expression.h"
#include "mongo/db/exec/sbe/values/bson.h"
#include "mongo/db/query/collection_query_info.h"
#include "mongo/db/query/explain.h"
#include "mongo/db/query/plan_ranker_util.h"
#include "mongo/db/query/query_planner.h"
#include "mongo/db/query/stage_builder_util.h"
#include "mongo/logv2/log.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kQuery
namespace mongo::sbe {
CandidatePlans MultiPlanner::plan(
std::vector<std::unique_ptr<QuerySolution>> solutions,
std::vector<std::pair<std::unique_ptr<PlanStage>, stage_builder::PlanStageData>> roots) {
auto candidates = collectExecutionStats(
std::move(solutions),
std::move(roots),
trial_period::getTrialPeriodMaxWorks(_opCtx,
_collections.getMainCollection(),
internalQueryPlanEvaluationWorksSbe.load(),
internalQueryPlanEvaluationCollFractionSbe.load()));
auto decision = uassertStatusOK(mongo::plan_ranker::pickBestPlan<PlanStageStats>(candidates));
return finalizeExecutionPlans(std::move(decision), std::move(candidates));
}
CandidatePlans MultiPlanner::finalizeExecutionPlans(
std::unique_ptr<mongo::plan_ranker::PlanRankingDecision> decision,
std::vector<plan_ranker::CandidatePlan> candidates) const {
invariant(decision);
// Make sure we have at least one plan which hasn't failed.
uassert(4822873,
"all candidate plans failed during multi planning",
std::count_if(candidates.begin(), candidates.end(), [](auto&& candidate) {
return candidate.status.isOK();
}) > 0);
auto&& stats = decision->getStats<sbe::PlanStageStats>();
const auto winnerIdx = decision->candidateOrder[0];
tassert(5323801,
str::stream() << "winner index is out of candidate plans bounds: " << winnerIdx << ", "
<< candidates.size(),
winnerIdx < candidates.size());
tassert(5323802,
str::stream() << "winner index is out of candidate plan stats bounds: " << winnerIdx
<< ", " << stats.candidatePlanStats.size(),
winnerIdx < stats.candidatePlanStats.size());
auto& winner = candidates[winnerIdx];
tassert(5323803,
str::stream() << "winning candidate returned an error: " << winner.status,
winner.status.isOK());
LOGV2_DEBUG(
4822875, 5, "Winning solution", "bestSolution"_attr = redact(winner.solution->toString()));
auto explainer =
plan_explainer_factory::make(winner.root.get(), &winner.data, winner.solution.get());
LOGV2_DEBUG(4822876, 2, "Winning plan", "planSummary"_attr = explainer->getPlanSummary());
// Close all candidate plans but the winner.
for (size_t ix = 1; ix < decision->candidateOrder.size(); ++ix) {
const auto planIdx = decision->candidateOrder[ix];
invariant(planIdx < candidates.size());
candidates[planIdx].root->close();
}
// An SBE tree that exited early by throwing an exception cannot be reused by design. To work
// around this limitation, we clone the tree from the original tree. If there is a pipeline in
// "_cq" the winning candidate will be extended by building a new SBE tree below, so we don't
// need to clone a new copy here if the winner exited early.
if (winner.exitedEarly && _cq.pipeline().empty()) {
// Remove all the registered plans from _yieldPolicy's list of trees.
_yieldPolicy->clearRegisteredPlans();
tassert(6142204,
"The winning CandidatePlan should contain the original plan",
winner.clonedPlan);
// Clone a new copy of the original plan to use for execution so that the 'clonedPlan' in
// 'winner' can be inserted into the plan cache while in a clean state.
winner.data = stage_builder::PlanStageData(winner.clonedPlan->second);
// When we clone the tree below, the new tree's stats will be zeroed out. If this is an
// explain operation, save the stats from the old tree before we discard it.
if (_cq.getExplain()) {
winner.data.savedStatsOnEarlyExit = winner.root->getStats(true /* includeDebugInfo */);
}
winner.root = winner.clonedPlan->first->clone();
stage_builder::prepareSlotBasedExecutableTree(
_opCtx, winner.root.get(), &winner.data, _cq, _collections, _yieldPolicy);
// Clear the results queue.
winner.results = {};
winner.root->open(false);
}
// Writes a cache entry for the winning plan to the plan cache if possible.
plan_cache_util::updatePlanCache(_opCtx,
_collections.getMainCollection(),
_cachingMode,
_cq,
std::move(decision),
candidates);
// Extend the winning candidate with the agg pipeline and rebuild the execution tree. Because
// the trial was done with find-only part of the query, we cannot reuse the results. The
// non-winning plans are only used in 'explain()' so, to save on unnecessary work, we extend
// them only if this is an 'explain()' request.
if (!_cq.pipeline().empty()) {
winner.root->close();
_yieldPolicy->clearRegisteredPlans();
auto solution = QueryPlanner::extendWithAggPipeline(
_cq, std::move(winner.solution), _queryParams.secondaryCollectionsInfo);
auto [rootStage, data] = stage_builder::buildSlotBasedExecutableTree(
_opCtx, _collections, _cq, *solution, _yieldPolicy);
// The winner might have been replanned. So, pass through the replanning reason to the new
// plan.
data.replanReason = std::move(winner.data.replanReason);
stage_builder::prepareSlotBasedExecutableTree(
_opCtx, rootStage.get(), &data, _cq, _collections, _yieldPolicy);
candidates[winnerIdx] = sbe::plan_ranker::CandidatePlan{
std::move(solution), std::move(rootStage), std::move(data)};
candidates[winnerIdx].root->open(false);
if (_cq.getExplain()) {
for (size_t i = 0; i < candidates.size(); ++i) {
if (i == winnerIdx)
continue; // have already done the winner
auto solution = QueryPlanner::extendWithAggPipeline(
_cq, std::move(candidates[i].solution), _queryParams.secondaryCollectionsInfo);
auto&& [rootStage, data] = stage_builder::buildSlotBasedExecutableTree(
_opCtx, _collections, _cq, *solution, _yieldPolicy);
candidates[i] = sbe::plan_ranker::CandidatePlan{
std::move(solution), std::move(rootStage), std::move(data)};
}
}
}
return {std::move(candidates), winnerIdx};
}
} // namespace mongo::sbe
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