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/**
* 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,
bool enforceUniquenessCheck,
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 requiresUnique,
const ShardKeyValidationBehaviors& behaviors);
void validateShardKeyIsNotEncrypted(OperationContext* opCtx,
const NamespaceString& nss,
const ShardKeyPattern& shardKeyPattern);
} // namespace shardkeyutil
} // namespace mongo
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