/usr/include/mongo/s/shardkey.h is in mongodb-dev 1:2.4.9-1ubuntu2.
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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 | // 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/>.
*/
#pragma once
#include "mongo/base/string_data.h"
#include "mongo/db/keypattern.h"
namespace mongo {
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' is a prefix (not necessarily contained) of 'otherPattern'.
*/
bool isPrefixOf( const KeyPattern& otherPattern ) const;
/**
* @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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