1 2 /** 3 * Copyright (C) 2018-present MongoDB, Inc. 4 * 5 * This program is free software: you can redistribute it and/or modify 6 * it under the terms of the Server Side Public License, version 1, 7 * as published by MongoDB, Inc. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * Server Side Public License for more details. 13 * 14 * You should have received a copy of the Server Side Public License 15 * along with this program. If not, see 16 * <http://www.mongodb.com/licensing/server-side-public-license>. 17 * 18 * As a special exception, the copyright holders give permission to link the 19 * code of portions of this program with the OpenSSL library under certain 20 * conditions as described in each individual source file and distribute 21 * linked combinations including the program with the OpenSSL library. You 22 * must comply with the Server Side Public License in all respects for 23 * all of the code used other than as permitted herein. If you modify file(s) 24 * with this exception, you may extend this exception to your version of the 25 * file(s), but you are not obligated to do so. If you do not wish to do so, 26 * delete this exception statement from your version. If you delete this 27 * exception statement from all source files in the program, then also delete 28 * it in the license file. 29 */ 30 31 #pragma once 32 33 #include <string> 34 35 #include "mongo/base/status.h" 36 #include "mongo/db/hasher.h" // For HashSeed. 37 #include "mongo/db/index/index_access_method.h" 38 #include "mongo/db/index/index_descriptor.h" 39 #include "mongo/db/jsobj.h" 40 41 namespace mongo { 42 43 class CollatorInterface; 44 45 /** 46 * This is the access method for "hashed" indices. 47 */ 48 class HashAccessMethod : public IndexAccessMethod { 49 public: 50 HashAccessMethod(IndexCatalogEntry* btreeState, SortedDataInterface* btree); 51 52 private: 53 /** 54 * Fills 'keys' with the keys that should be generated for 'obj' on this index. 55 * 56 * This function ignores the 'multikeyPaths' pointer because hashed indexes don't support 57 * tracking path-level multikey information. 58 */ 59 void doGetKeys(const BSONObj& obj, 60 GetKeysContext context, 61 BSONObjSet* keys, 62 MultikeyPaths* multikeyPaths) const final; 63 64 // Only one of our fields is hashed. This is the field name for it. 65 std::string _hashedField; 66 67 // _seed defaults to zero. 68 HashSeed _seed; 69 70 // _hashVersion defaults to zero. 71 int _hashVersion; 72 73 BSONObj _missingKey; 74 75 // Null if this index orders strings according to the simple binary compare. If non-null, 76 // represents the collator used to generate index keys for indexed strings. 77 const CollatorInterface* _collator; 78 }; 79 80 } // namespace mongo 81