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
|
/**
* 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/dbdirectclient.h"
#include "mongo/s/chunk_manager.h"
#include "mongo/s/client/shard.h"
#include "mongo/s/shard_util.h"
namespace mongo {
namespace shardkeyutil {
/**
* Encapsulates the various steps performed when validating a proposed shard key against the
* existing indexes for a collection when sharding a collection or refining its shard key.
* Subclasses provide the implementation details specific to either case.
*/
class ShardKeyValidationBehaviors {
public:
virtual ~ShardKeyValidationBehaviors() {}
virtual std::vector<BSONObj> loadIndexes(const NamespaceString& nss) const = 0;
virtual void verifyUsefulNonMultiKeyIndex(const NamespaceString& nss,
const BSONObj& proposedKey) const = 0;
virtual void verifyCanCreateShardKeyIndex(const NamespaceString& nss) const = 0;
virtual void createShardKeyIndex(const NamespaceString& nss,
const BSONObj& proposedKey,
const boost::optional<BSONObj>& defaultCollation,
bool unique) const = 0;
};
/**
* Implementation of steps for validating a shard key for shardCollection.
*/
class ValidationBehaviorsShardCollection final : public ShardKeyValidationBehaviors {
public:
ValidationBehaviorsShardCollection(OperationContext* opCtx)
: _localClient(std::make_unique<DBDirectClient>(opCtx)) {}
std::vector<BSONObj> loadIndexes(const NamespaceString& nss) const override;
void verifyUsefulNonMultiKeyIndex(const NamespaceString& nss,
const BSONObj& proposedKey) const override;
void verifyCanCreateShardKeyIndex(const NamespaceString& nss) const override;
void createShardKeyIndex(const NamespaceString& nss,
const BSONObj& proposedKey,
const boost::optional<BSONObj>& defaultCollation,
bool unique) const override;
private:
std::unique_ptr<DBDirectClient> _localClient;
};
/**
* Implementation of steps for validating a shard key for refineCollectionShardKey.
*/
class ValidationBehaviorsRefineShardKey final : public ShardKeyValidationBehaviors {
public:
ValidationBehaviorsRefineShardKey(OperationContext* opCtx, const NamespaceString& nss);
std::vector<BSONObj> loadIndexes(const NamespaceString& nss) const override;
void verifyUsefulNonMultiKeyIndex(const NamespaceString& nss,
const BSONObj& proposedKey) const override;
void verifyCanCreateShardKeyIndex(const NamespaceString& nss) const override;
void createShardKeyIndex(const NamespaceString& nss,
const BSONObj& proposedKey,
const boost::optional<BSONObj>& defaultCollation,
bool unique) const override;
private:
OperationContext* _opCtx;
ChunkManager _cm;
std::shared_ptr<Shard> _indexShard;
};
/**
* Compares the proposed shard key with the collection's existing indexes to ensure they are a legal
* combination.
*
* Creates the required index if and only if (i) the collection is empty, (ii) no index on the
* shard key exists, and (iii) the collection is not having its shard key refined.
*
* The proposed shard key must be validated against the set of existing indexes.
* In particular, we must ensure the following constraints:
*
* 1. All existing unique indexes, except those which start with the _id index,
* must contain the proposed key as a prefix (uniqueness of the _id index is
* ensured by the _id generation process or guaranteed by the user).
*
* 2. If the collection is not empty or we are refining its shard key, there must exist at least one
* index that is "useful" for the proposed key. A "useful" index is defined as adhering to
* all of the following properties:
* i. contains proposedKey as a prefix
* ii. is not a sparse index, partial index, or index with a non-simple collation
* iii. is not multikey (maybe lift this restriction later)
* iv. if a hashed index, has default seed (lift this restriction later)
*
* 3. If the proposed shard key is specified as unique, there must exist a useful,
* unique index exactly equal to the proposedKey (not just a prefix).
*
* After validating these constraints:
*
* 4. If there is no useful index, and the collection is non-empty or we are refining the
* collection's shard key, we must fail.
*
* 5. If the collection is empty and we are not refining the collection's shard key, and it's
* still possible to create an index on the proposed key, we go ahead and do so.
*
* Returns true if the index has been created, false otherwise.
*/
bool validateShardKeyIndexExistsOrCreateIfPossible(OperationContext* opCtx,
const NamespaceString& nss,
const ShardKeyPattern& shardKeyPattern,
const boost::optional<BSONObj>& defaultCollation,
bool unique,
const ShardKeyValidationBehaviors& behaviors);
/**
* Compares the proposed shard key with the collection's existing indexes to ensure they are a legal
* combination.
*
* Returns true if the shard key is valid and already exists. Steps 1, 2 and 3 of the previous
* function.
*
*/
bool validShardKeyIndexExists(OperationContext* opCtx,
const NamespaceString& nss,
const ShardKeyPattern& shardKeyPattern,
const boost::optional<BSONObj>& defaultCollation,
bool unique,
const ShardKeyValidationBehaviors& behaviors);
} // namespace shardkeyutil
} // namespace mongo
|