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
|
/**
* 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/>.
*/
#pragma once
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/diskloc.h"
#include "mongo/db/index/btree_index_cursor.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/query/index_bounds.h"
#include "mongo/platform/unordered_set.h"
namespace mongo {
class IndexAccessMethod;
class IndexCursor;
class IndexDescriptor;
class WorkingSet;
struct IndexScanParams {
IndexScanParams() : descriptor(NULL), direction(1), limit(0),
forceBtreeAccessMethod(false) { }
IndexDescriptor* descriptor;
IndexBounds bounds;
int direction;
// This only matters for 2d indices and will be ignored by every other index.
int limit;
// Special indices internally open an IndexCursor over themselves but as a straight Btree.
bool forceBtreeAccessMethod;
};
/**
* Stage scans over an index from startKey to endKey, returning results that pass the provided
* filter. Internally dedups on DiskLoc.
*
* Sub-stage preconditions: None. Is a leaf and consumes no stage data.
*/
class IndexScan : public PlanStage {
public:
IndexScan(const IndexScanParams& params, WorkingSet* workingSet,
const MatchExpression* filter);
virtual ~IndexScan() { }
virtual StageState work(WorkingSetID* out);
virtual bool isEOF();
virtual void prepareToYield();
virtual void recoverFromYield();
virtual void invalidate(const DiskLoc& dl);
virtual PlanStageStats* getStats();
private:
/** See if the cursor is pointing at or past _endKey, if _endKey is non-empty. */
void checkEnd();
// The WorkingSet we annotate with results. Not owned by us.
WorkingSet* _workingSet;
// Index access.
scoped_ptr<IndexAccessMethod> _iam;
scoped_ptr<IndexCursor> _indexCursor;
scoped_ptr<IndexDescriptor> _descriptor;
// Have we hit the end of the index scan?
bool _hitEnd;
// Contains expressions only over fields in the index key. We assume this is built
// correctly by whomever creates this class.
// The filter is not owned by us.
const MatchExpression* _filter;
// Could our index have duplicates? If so, we use _returned to dedup.
bool _shouldDedup;
unordered_set<DiskLoc, DiskLoc::Hasher> _returned;
// For yielding.
BSONObj _savedKey;
DiskLoc _savedLoc;
// True if there was a yield and the yield changed the cursor position.
bool _yieldMovedCursor;
IndexScanParams _params;
// For our "fast" Btree-only navigation AKA the index bounds optimization.
scoped_ptr<IndexBoundsChecker> _checker;
BtreeIndexCursor* _btreeCursor;
int _keyEltsToUse;
bool _movePastKeyElts;
vector<const BSONElement*> _keyElts;
vector<bool> _keyEltsInc;
// Stats
CommonStats _commonStats;
IndexScanStats _specificStats;
};
} // namespace mongo
|
