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
|
/**
* Copyright (C) 2019-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_stage.h"
namespace mongo {
/**
* This stage returns the index key or keys, used for executing the query, for each document in
* the result. If the query does not use an index to perform the read operation, the stage returns
* empty documents.
*
* If 'sortKeyMetaFields' vector is specified while constructing this stage, each element in this
* array will be treated as a field name which will be added to the output document and will
* hold a sort key for the document in the result set, if the sort key exists. The elements in this
* array are the values specified in the 'sortKey' meta-projection.
*/
class ReturnKeyStage : public PlanStage {
public:
static constexpr StringData kStageName = "RETURN_KEY"_sd;
ReturnKeyStage(OperationContext* opCtx,
std::vector<FieldPath> sortKeyMetaFields,
WorkingSet* ws,
SortKeyFormat sortKeyFormat,
std::unique_ptr<PlanStage> child)
: PlanStage(opCtx, std::move(child), kStageName.rawData()),
_ws(*ws),
_sortKeyMetaFields(std::move(sortKeyMetaFields)),
_sortKeyFormat(sortKeyFormat) {}
StageType stageType() const final {
return STAGE_RETURN_KEY;
}
bool isEOF() final {
return child()->isEOF();
}
StageState doWork(WorkingSetID* out) final;
std::unique_ptr<PlanStageStats> getStats() final;
const SpecificStats* getSpecificStats() const final {
return &_specificStats;
}
private:
Status _extractIndexKey(WorkingSetMember* member);
WorkingSet& _ws;
ReturnKeyStats _specificStats;
// The field names associated with any sortKey meta-projection(s). Empty if there is no sortKey
// meta-projection.
std::vector<FieldPath> _sortKeyMetaFields;
const SortKeyFormat _sortKeyFormat;
};
} // namespace mongo
|
