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// shardkey.h
/**
* Copyright (C) 2008 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/base/string_data.h"
#include "mongo/db/keypattern.h"
namespace mongo {
/**
* THIS FUNCTIONALITY IS DEPRECATED
* Everything BSON related in this file should migrate gradually to s/shard_key_pattern.h, new
* functionality should not go here.
*/
class Chunk;
class FieldRangeSet;
/* A ShardKeyPattern is a pattern indicating what data to extract from the object to make the shard key from.
Analogous to an index key pattern.
*/
class ShardKeyPattern {
public:
ShardKeyPattern( BSONObj p = BSONObj() );
/**
global min is the lowest possible value for this key
e.g. { num : MinKey }
*/
BSONObj globalMin() const { return gMin; }
/**
global max is the highest possible value for this key
*/
BSONObj globalMax() const { return gMax; }
bool isGlobalMin( const BSONObj& k ) const {
return k.woCompare( globalMin() ) == 0;
}
bool isGlobalMax( const BSONObj& k ) const {
return k.woCompare( globalMax() ) == 0;
}
bool isGlobal( const BSONObj& k ) const {
return isGlobalMin( k ) || isGlobalMax( k );
}
/**
@return whether or not obj has all fields in this shard key pattern
e.g.
ShardKey({num:1}).hasShardKey({ name:"joe", num:3 }) is true
ShardKey({"a.b":1}).hasShardKey({ "a.b":"joe"}) is true
ShardKey({"a.b":1}).hasShardKey({ "a": {"b":"joe"}}) is true
ShardKey({num:1}).hasShardKey({ name:"joe"}) is false
ShardKey({num:1}).hasShardKey({ name:"joe", num:{$gt:3} }) is false
see unit test for more examples
*/
bool hasShardKey( const BSONObj& obj ) const;
BSONObj key() const { return pattern.toBSON(); }
string toString() const;
BSONObj extractKey(const BSONObj& from) const;
bool partOfShardKey(const StringData& key ) const {
return pattern.hasField(key);
}
BSONObj extendRangeBound( const BSONObj& bound , bool makeUpperInclusive ) const {
return pattern.extendRangeBound( bound , makeUpperInclusive );
}
/**
* @return
* true if this shard key is compatible with a unique index on 'uniqueIndexPattern'.
* Primarily this just checks whether 'this' is a prefix of 'uniqueIndexPattern',
* However it does not need to be an exact syntactic prefix due to "hashed"
* indexes or mismatches in ascending/descending order. Also, uniqueness of the
* _id field is guaranteed by the generation process (or by the user) so every
* index that begins with _id is unique index compatible with any shard key.
* Examples:
* shard key {a : 1} is compatible with a unique index on {_id : 1}
* shard key {a : 1} is compatible with a unique index on {a : 1 , b : 1}
* shard key {a : 1} is compatible with a unique index on {a : -1 , b : 1 }
* shard key {a : "hashed"} is compatible with a unique index on {a : 1}
* shard key {a : 1} is not compatible with a unique index on {b : 1}
* shard key {a : "hashed" , b : 1 } is not compatible with unique index on { b : 1 }
* Note:
* this method assumes that 'uniqueIndexPattern' is a valid index pattern,
* and is capable of being a unique index. A pattern like { k : "hashed" }
* is never capable of being a unique index, and thus is an invalid setting
* for the 'uniqueIndexPattern' argument.
*/
bool isUniqueIndexCompatible( const KeyPattern& uniqueIndexPattern ) const;
/**
* @return
* true if keyPattern contains any computed values, (e.g. {a : "hashed"})
* false if keyPattern consists of only ascending/descending fields (e.g. {a : 1, b : -1})
* With our current index expression language, "special" shard keys are any keys
* that are not a simple list of field names and 1/-1 values.
*/
bool isSpecial() const { return pattern.isSpecial(); }
/**
* @return BSONObj with _id and shardkey at front. May return original object.
*/
BSONObj moveToFront(const BSONObj& obj) const;
/**@param queryConstraints a FieldRangeSet formed from parsing a query
* @return an ordered list of bounds generated using this KeyPattern
* and the constraints from the FieldRangeSet
*
* The value of frsp->matchPossibleForSingleKeyFRS(fromQuery) should be true,
* otherwise this function could throw.
*
*/
BoundList keyBounds( const FieldRangeSet& queryConstraints ) const{
return pattern.keyBounds( queryConstraints );
}
private:
KeyPattern pattern;
BSONObj gMin;
BSONObj gMax;
/* question: better to have patternfields precomputed or not? depends on if we use copy constructor often. */
set<string> patternfields;
};
inline BSONObj ShardKeyPattern::extractKey(const BSONObj& from) const {
BSONObj k = pattern.extractSingleKey( from );
uassert(13334, "Shard Key must be less than 512 bytes", k.objsize() < 512);
return k;
}
}
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