// Copyright (c) 2011-present, Facebook, Inc. All rights reserved. // This source code is licensed under both the GPLv2 (found in the // COPYING file in the root directory) and Apache 2.0 License // (found in the LICENSE.Apache file in the root directory). // // Copyright (c) 2011 The LevelDB Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. See the AUTHORS file for names of contributors. #pragma once #include namespace rocksdb { class Cache; class Comparator; class Env; class FilterPolicy; class Logger; struct Options; class Snapshot; enum CompressionType : unsigned char; // Options to control the behavior of a database (passed to // DB::Open). A LevelDBOptions object can be initialized as though // it were a LevelDB Options object, and then it can be converted into // a RocksDB Options object. struct LevelDBOptions { // ------------------- // Parameters that affect behavior // Comparator used to define the order of keys in the table. // Default: a comparator that uses lexicographic byte-wise ordering // // REQUIRES: The client must ensure that the comparator supplied // here has the same name and orders keys *exactly* the same as the // comparator provided to previous open calls on the same DB. const Comparator* comparator; // If true, the database will be created if it is missing. // Default: false bool create_if_missing; // If true, an error is raised if the database already exists. // Default: false bool error_if_exists; // If true, the implementation will do aggressive checking of the // data it is processing and will stop early if it detects any // errors. This may have unforeseen ramifications: for example, a // corruption of one DB entry may cause a large number of entries to // become unreadable or for the entire DB to become unopenable. // Default: false bool paranoid_checks; // Use the specified object to interact with the environment, // e.g. to read/write files, schedule background work, etc. // Default: Env::Default() Env* env; // Any internal progress/error information generated by the db will // be written to info_log if it is non-NULL, or to a file stored // in the same directory as the DB contents if info_log is NULL. // Default: NULL Logger* info_log; // ------------------- // Parameters that affect performance // Amount of data to build up in memory (backed by an unsorted log // on disk) before converting to a sorted on-disk file. // // Larger values increase performance, especially during bulk loads. // Up to two write buffers may be held in memory at the same time, // so you may wish to adjust this parameter to control memory usage. // Also, a larger write buffer will result in a longer recovery time // the next time the database is opened. // // Default: 4MB size_t write_buffer_size; // Number of open files that can be used by the DB. You may need to // increase this if your database has a large working set (budget // one open file per 2MB of working set). // // Default: 1000 int max_open_files; // Control over blocks (user data is stored in a set of blocks, and // a block is the unit of reading from disk). // If non-NULL, use the specified cache for blocks. // If NULL, leveldb will automatically create and use an 8MB internal cache. // Default: NULL Cache* block_cache; // Approximate size of user data packed per block. Note that the // block size specified here corresponds to uncompressed data. The // actual size of the unit read from disk may be smaller if // compression is enabled. This parameter can be changed dynamically. // // Default: 4K size_t block_size; // Number of keys between restart points for delta encoding of keys. // This parameter can be changed dynamically. Most clients should // leave this parameter alone. // // Default: 16 int block_restart_interval; // Compress blocks using the specified compression algorithm. This // parameter can be changed dynamically. // // Default: kSnappyCompression, which gives lightweight but fast // compression. // // Typical speeds of kSnappyCompression on an Intel(R) Core(TM)2 2.4GHz: // ~200-500MB/s compression // ~400-800MB/s decompression // Note that these speeds are significantly faster than most // persistent storage speeds, and therefore it is typically never // worth switching to kNoCompression. Even if the input data is // incompressible, the kSnappyCompression implementation will // efficiently detect that and will switch to uncompressed mode. CompressionType compression; // If non-NULL, use the specified filter policy to reduce disk reads. // Many applications will benefit from passing the result of // NewBloomFilterPolicy() here. // // Default: NULL const FilterPolicy* filter_policy; // Create a LevelDBOptions object with default values for all fields. LevelDBOptions(); }; // Converts a LevelDBOptions object into a RocksDB Options object. Options ConvertOptions(const LevelDBOptions& leveldb_options); } // namespace rocksdb