91 lines
3.5 KiB
C++
91 lines
3.5 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#ifndef STORAGE_ROCKSDB_UNIVERSAL_COMPACTION_OPTIONS_H
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#define STORAGE_ROCKSDB_UNIVERSAL_COMPACTION_OPTIONS_H
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#include <stdint.h>
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#include <climits>
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#include <vector>
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namespace rocksdb {
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//
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// Algorithm used to make a compaction request stop picking new files
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// into a single compaction run
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//
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enum CompactionStopStyle {
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kCompactionStopStyleSimilarSize, // pick files of similar size
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kCompactionStopStyleTotalSize // total size of picked files > next file
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};
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class CompactionOptionsUniversal {
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public:
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// Percentage flexibilty while comparing file size. If the candidate file(s)
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// size is 1% smaller than the next file's size, then include next file into
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// this candidate set. // Default: 1
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unsigned int size_ratio;
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// The minimum number of files in a single compaction run. Default: 2
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unsigned int min_merge_width;
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// The maximum number of files in a single compaction run. Default: UINT_MAX
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unsigned int max_merge_width;
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// The size amplification is defined as the amount (in percentage) of
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// additional storage needed to store a single byte of data in the database.
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// For example, a size amplification of 2% means that a database that
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// contains 100 bytes of user-data may occupy upto 102 bytes of
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// physical storage. By this definition, a fully compacted database has
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// a size amplification of 0%. Rocksdb uses the following heuristic
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// to calculate size amplification: it assumes that all files excluding
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// the earliest file contribute to the size amplification.
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// Default: 200, which means that a 100 byte database could require upto
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// 300 bytes of storage.
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unsigned int max_size_amplification_percent;
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// If this option is set to be -1 (the default value), all the output files
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// will follow compression type specified.
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//
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// If this option is not negative, we will try to make sure compressed
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// size is just above this value. In normal cases, at least this percentage
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// of data will be compressed.
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// When we are compacting to a new file, here is the criteria whether
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// it needs to be compressed: assuming here are the list of files sorted
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// by generation time:
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// A1...An B1...Bm C1...Ct
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// where A1 is the newest and Ct is the oldest, and we are going to compact
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// B1...Bm, we calculate the total size of all the files as total_size, as
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// well as the total size of C1...Ct as total_C, the compaction output file
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// will be compressed iff
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// total_C / total_size < this percentage
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// Default: -1
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int compression_size_percent;
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// The algorithm used to stop picking files into a single compaction run
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// Default: kCompactionStopStyleTotalSize
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CompactionStopStyle stop_style;
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// Option to optimize the universal multi level compaction by enabling
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// trivial move for non overlapping files.
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// Default: false
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bool allow_trivial_move;
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// Default set of parameters
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CompactionOptionsUniversal()
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: size_ratio(1),
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min_merge_width(2),
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max_merge_width(UINT_MAX),
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max_size_amplification_percent(200),
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compression_size_percent(-1),
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stop_style(kCompactionStopStyleTotalSize),
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allow_trivial_move(false) {}
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};
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} // namespace rocksdb
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#endif // STORAGE_ROCKSDB_UNIVERSAL_COMPACTION_OPTIONS_H
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