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111 lines
3.3 KiB
C++
111 lines
3.3 KiB
C++
// shardkey.h
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/**
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* Copyright (C) 2008 10gen Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "../client/dbclient.h"
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namespace mongo {
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class Chunk;
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/* A ShardKeyPattern is a pattern indicating what data to extract from the object to make the shard key from.
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Analogous to an index key pattern.
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*/
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class ShardKeyPattern {
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public:
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ShardKeyPattern( BSONObj p = BSONObj() );
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/**
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global min is the lowest possible value for this key
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e.g. { num : MinKey }
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*/
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BSONObj globalMin() const { return gMin; }
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/**
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global max is the highest possible value for this key
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*/
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BSONObj globalMax() const { return gMax; }
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bool isGlobalMin( const BSONObj& k ) const {
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return k.woCompare( globalMin() ) == 0;
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}
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bool isGlobalMax( const BSONObj& k ) const {
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return k.woCompare( globalMax() ) == 0;
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}
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bool isGlobal( const BSONObj& k ) const {
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return isGlobalMin( k ) || isGlobalMax( k );
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}
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/** compare shard keys from the objects specified
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l < r negative
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l == r 0
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l > r positive
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*/
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int compare( const BSONObj& l , const BSONObj& r ) const;
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/**
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@return whether or not obj has all fields in this shard key pattern
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e.g.
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ShardKey({num:1}).hasShardKey({ name:"joe", num:3 }) is true
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*/
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bool hasShardKey( const BSONObj& obj ) const;
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BSONObj key() const { return pattern; }
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string toString() const;
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BSONObj extractKey(const BSONObj& from) const;
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bool partOfShardKey(const char* key ) const {
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return pattern.hasField(key);
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}
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bool partOfShardKey(const string& key ) const {
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return pattern.hasField(key.c_str());
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}
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/**
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* @return
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* true if 'this' is a prefix (not necessarily contained) of 'otherPattern'.
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*/
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bool isPrefixOf( const BSONObj& otherPattern ) const;
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/**
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* @return BSONObj with _id and shardkey at front. May return original object.
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*/
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BSONObj moveToFront(const BSONObj& obj) const;
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private:
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BSONObj pattern;
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BSONObj gMin;
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BSONObj gMax;
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/* question: better to have patternfields precomputed or not? depends on if we use copy constructor often. */
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set<string> patternfields;
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};
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inline BSONObj ShardKeyPattern::extractKey(const BSONObj& from) const {
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BSONObj k = from.extractFields(pattern);
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uassert(13334, "Shard Key must be less than 512 bytes", k.objsize() < 512);
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return k;
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}
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}
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