1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
/**
* 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.
*/
#pragma once
#include "mongo/db/exec/plan_stats.h"
#include "mongo/db/exec/sbe/stages/plan_stats.h"
#include "mongo/util/container_size_helper.h"
#include "mongo/util/visit_helper.h"
namespace mongo::plan_ranker {
struct StatsDetails {
// Execution stats for each candidate plan sorted in descending order by score.
std::vector<std::unique_ptr<PlanStageStats>> candidatePlanStats;
};
struct SBEStatsDetails {
// Execution stats for each candidate plan sorted in descending order by score.
std::vector<std::unique_ptr<mongo::sbe::PlanStageStats>> candidatePlanStats;
// A serialized winning plan is it would appear in the Explain output at "queryPlanner"
// verbosity.
BSONObj serializedWinningPlan;
};
template <class Key>
struct StatsToDetailMap {};
template <>
struct StatsToDetailMap<sbe::PlanStageStats> {
using Value = SBEStatsDetails;
};
template <>
struct StatsToDetailMap<PlanStageStats> {
using Value = StatsDetails;
};
/**
* Information about why a plan was picked to be the best. Data here is placed into the cache
* and used to compare expected performance with actual.
*/
struct PlanRankingDecision {
PlanRankingDecision() {}
/**
* Make a deep copy.
*/
std::unique_ptr<PlanRankingDecision> clone() const {
auto decision = std::make_unique<PlanRankingDecision>();
stdx::visit(
visit_helper::Overloaded{
[&decision](const StatsDetails& details) {
std::vector<std::unique_ptr<PlanStageStats>> copy;
copy.reserve(details.candidatePlanStats.size());
for (auto&& stats : details.candidatePlanStats) {
invariant(stats);
copy.emplace_back(stats->clone());
}
decision->stats = StatsDetails{std::move(copy)};
},
[&decision](const SBEStatsDetails& details) {
std::vector<std::unique_ptr<mongo::sbe::PlanStageStats>> copy;
copy.reserve(details.candidatePlanStats.size());
for (auto&& stats : details.candidatePlanStats) {
invariant(stats);
copy.emplace_back(stats->clone());
}
decision->stats =
SBEStatsDetails{std::move(copy), details.serializedWinningPlan};
}},
stats);
decision->scores = scores;
decision->candidateOrder = candidateOrder;
decision->failedCandidates = failedCandidates;
return decision;
}
uint64_t estimateObjectSizeInBytes() const {
return // Add size of 'stats' instance.
stdx::visit(
visit_helper::Overloaded{
[](const StatsDetails& details) {
return container_size_helper::estimateObjectSizeInBytes(
details.candidatePlanStats,
[](auto&& stat) { return stat->estimateObjectSizeInBytes(); },
true);
},
[](const SBEStatsDetails& details) {
return details.serializedWinningPlan.objsize() +
container_size_helper::estimateObjectSizeInBytes(
details.candidatePlanStats,
[](auto&& stat) { return stat->estimateObjectSizeInBytes(); },
true);
}},
stats) +
// Add size of each element in 'candidateOrder' vector.
container_size_helper::estimateObjectSizeInBytes(candidateOrder) +
// Add size of each element in 'failedCandidates' vector.
container_size_helper::estimateObjectSizeInBytes(failedCandidates) +
// Add size of each element in 'scores' vector.
container_size_helper::estimateObjectSizeInBytes(scores) +
// Add size of the object.
sizeof(*this);
}
template <typename PlanStageStatsType>
const auto& getStats() const {
return stdx::get<typename StatsToDetailMap<PlanStageStatsType>::Value>(stats);
}
template <typename PlanStageStatsType>
auto& getStats() {
return stdx::get<typename StatsToDetailMap<PlanStageStatsType>::Value>(stats);
}
/*
* Returns true if there are at least two possible plans, and at least the top two plans
* have the same scores.
*/
bool tieForBest() const {
if (scores.size() > 1) {
const double epsilon = 1e-10;
return (std::abs(scores[0] - scores[1]) < epsilon);
}
return false;
}
// Execution stats details for each candidate plan.
stdx::variant<StatsDetails, SBEStatsDetails> stats;
// The "goodness" score corresponding to 'stats'.
// Sorted in descending order.
std::vector<double> scores;
// Ordering of original plans in descending of score.
// Filled in by PlanScorer::pickBestPlan(candidates, ...)
// so that candidates[candidateOrder[0]] refers to the best plan
// with corresponding cores[0] and stats[0]. Runner-up would be
// candidates[candidateOrder[1]] followed by
// candidates[candidateOrder[2]], ...
//
// Contains only non-failing plans.
std::vector<size_t> candidateOrder;
// Contains the list of original plans that failed.
//
// Like 'candidateOrder', the contents of this array are indicies into the 'candidates' array.
std::vector<size_t> failedCandidates;
};
} // namespace mongo::plan_ranker
|
