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
|
/**
* Copyright (C) 2013 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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/query/canonical_query.h"
#include "mongo/db/query/query_planner_params.h"
#include "mongo/db/query/query_solution.h"
namespace mongo {
class CachedSolution;
class Collection;
/**
* QueryPlanner's job is to provide an entry point to the query planning and optimization
* process.
*/
class QueryPlanner {
public:
// Identifies the version of the query planner module. Reported in explain.
static const int kPlannerVersion;
/**
* Outputs a series of possible solutions for the provided 'query' into 'out'. Uses the
* indices and other data in 'params' to plan with.
*
* Caller owns pointers in *out.
*/
static Status plan(const CanonicalQuery& query,
const QueryPlannerParams& params,
std::vector<QuerySolution*>* out);
/**
* Helper that does most of the heavy lifting for the planFromCache
* method which this overloads. Whereas the overloaded version plans
* from cache twice (once for the winning solution and once from the
* backup solution), this version plans from cache once.
*
* It requires a single SolutionCacheData, rather than a CachedSolution, which
* owns a vector of SolutionCacheData instances.
*/
static Status planFromCache(const CanonicalQuery& query,
const QueryPlannerParams& params,
const SolutionCacheData& cacheData,
QuerySolution** out);
/**
* Attempt to generate a query solution, given data retrieved
* from the plan cache.
*
* @param query -- query for which we are generating a plan
* @param params -- planning parameters
* @param cachedSoln -- the CachedSolution retrieved from the plan cache.
* @param out -- an out-parameter which will be filled in with the solution
* generated from the cache data
* @param backupOut -- if 'out' contains a blocking sort, then backoutOut may
* contain an alternative solution with no blocking sort; otherwise it will
* contain NULL on return.
*/
static Status planFromCache(const CanonicalQuery& query,
const QueryPlannerParams& params,
const CachedSolution& cachedSoln,
QuerySolution** out,
QuerySolution** backupOut);
/**
* Used to generated the index tag tree that will be inserted
* into the plan cache. This data gets stashed inside a QuerySolution
* until it can be inserted into the cache proper.
*
* @param taggedTree -- a MatchExpression with index tags that has been
* produced by the enumerator.
* @param relevantIndices -- a list of the index entries used to tag
* the tree (i.e. index numbers in the tags refer to entries in this vector)
*
* On success, a new tagged tree is returned through the out-parameter 'out'.
* The caller has ownership of both taggedTree and *out.
*
* On failure, 'out' is set to NULL.
*/
static Status cacheDataFromTaggedTree(const MatchExpression* const taggedTree,
const std::vector<IndexEntry>& relevantIndices,
PlanCacheIndexTree** out);
/**
* @param filter -- an untagged MatchExpression
* @param indexTree -- a tree structure retrieved from the
* cache with index tags that indicates how 'filter' should
* be tagged.
* @param indexMap -- needed in order to put the proper index
* numbers inside the index tags
*
* On success, 'filter' is mutated so that it has all the
* index tags needed in order for the access planner to recreate
* the cached plan.
*
* On failure, the tag state attached to the nodes of 'filter'
* is invalid. Planning from the cache should be aborted.
*
* Does not take ownership of either filter or indexTree.
*/
static Status tagAccordingToCache(MatchExpression* filter,
const PlanCacheIndexTree* const indexTree,
const std::map<BSONObj, size_t>& indexMap);
};
} // namespace mongo
|
