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// 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).
#pragma once
#include <stdint.h>
#include <climits>
#include <vector>
namespace rocksdb {
//
// Algorithm used to make a compaction request stop picking new files
// into a single compaction run
//
enum CompactionStopStyle {
kCompactionStopStyleSimilarSize, // pick files of similar size
kCompactionStopStyleTotalSize // total size of picked files > next file
};
class CompactionOptionsUniversal {
public:
// Percentage flexibility while comparing file size. If the candidate file(s)
// size is 1% smaller than the next file's size, then include next file into
// this candidate set. // Default: 1
unsigned int size_ratio;
// The minimum number of files in a single compaction run. Default: 2
unsigned int min_merge_width;
// The maximum number of files in a single compaction run. Default: UINT_MAX
unsigned int max_merge_width;
// The size amplification is defined as the amount (in percentage) of
// additional storage needed to store a single byte of data in the database.
// For example, a size amplification of 2% means that a database that
// contains 100 bytes of user-data may occupy upto 102 bytes of
// physical storage. By this definition, a fully compacted database has
// a size amplification of 0%. Rocksdb uses the following heuristic
// to calculate size amplification: it assumes that all files excluding
// the earliest file contribute to the size amplification.
// Default: 200, which means that a 100 byte database could require upto
// 300 bytes of storage.
unsigned int max_size_amplification_percent;
// If this option is set to be -1 (the default value), all the output files
// will follow compression type specified.
//
// If this option is not negative, we will try to make sure compressed
// size is just above this value. In normal cases, at least this percentage
// of data will be compressed.
// When we are compacting to a new file, here is the criteria whether
// it needs to be compressed: assuming here are the list of files sorted
// by generation time:
// A1...An B1...Bm C1...Ct
// where A1 is the newest and Ct is the oldest, and we are going to compact
// B1...Bm, we calculate the total size of all the files as total_size, as
// well as the total size of C1...Ct as total_C, the compaction output file
// will be compressed iff
// total_C / total_size < this percentage
// Default: -1
int compression_size_percent;
// The algorithm used to stop picking files into a single compaction run
// Default: kCompactionStopStyleTotalSize
CompactionStopStyle stop_style;
// Option to optimize the universal multi level compaction by enabling
// trivial move for non overlapping files.
// Default: false
bool allow_trivial_move;
// Default set of parameters
CompactionOptionsUniversal()
: size_ratio(1),
min_merge_width(2),
max_merge_width(UINT_MAX),
max_size_amplification_percent(200),
compression_size_percent(-1),
stop_style(kCompactionStopStyleTotalSize),
allow_trivial_move(false) {}
};
} // namespace rocksdb
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