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7c673cae | 1 | // Copyright (c) 2011-present, Facebook, Inc. All rights reserved. |
11fdf7f2 TL |
2 | // This source code is licensed under both the GPLv2 (found in the |
3 | // COPYING file in the root directory) and Apache 2.0 License | |
4 | // (found in the LICENSE.Apache file in the root directory). | |
7c673cae | 5 | |
11fdf7f2 | 6 | #pragma once |
7c673cae FG |
7 | |
8 | #include <stdint.h> | |
9 | #include <climits> | |
10 | #include <vector> | |
11 | ||
12 | namespace rocksdb { | |
13 | ||
14 | // | |
15 | // Algorithm used to make a compaction request stop picking new files | |
16 | // into a single compaction run | |
17 | // | |
18 | enum CompactionStopStyle { | |
19 | kCompactionStopStyleSimilarSize, // pick files of similar size | |
20 | kCompactionStopStyleTotalSize // total size of picked files > next file | |
21 | }; | |
22 | ||
23 | class CompactionOptionsUniversal { | |
24 | public: | |
25 | ||
11fdf7f2 | 26 | // Percentage flexibility while comparing file size. If the candidate file(s) |
7c673cae FG |
27 | // size is 1% smaller than the next file's size, then include next file into |
28 | // this candidate set. // Default: 1 | |
29 | unsigned int size_ratio; | |
30 | ||
31 | // The minimum number of files in a single compaction run. Default: 2 | |
32 | unsigned int min_merge_width; | |
33 | ||
34 | // The maximum number of files in a single compaction run. Default: UINT_MAX | |
35 | unsigned int max_merge_width; | |
36 | ||
37 | // The size amplification is defined as the amount (in percentage) of | |
38 | // additional storage needed to store a single byte of data in the database. | |
39 | // For example, a size amplification of 2% means that a database that | |
40 | // contains 100 bytes of user-data may occupy upto 102 bytes of | |
41 | // physical storage. By this definition, a fully compacted database has | |
42 | // a size amplification of 0%. Rocksdb uses the following heuristic | |
43 | // to calculate size amplification: it assumes that all files excluding | |
44 | // the earliest file contribute to the size amplification. | |
45 | // Default: 200, which means that a 100 byte database could require upto | |
46 | // 300 bytes of storage. | |
47 | unsigned int max_size_amplification_percent; | |
48 | ||
49 | // If this option is set to be -1 (the default value), all the output files | |
50 | // will follow compression type specified. | |
51 | // | |
52 | // If this option is not negative, we will try to make sure compressed | |
53 | // size is just above this value. In normal cases, at least this percentage | |
54 | // of data will be compressed. | |
55 | // When we are compacting to a new file, here is the criteria whether | |
56 | // it needs to be compressed: assuming here are the list of files sorted | |
57 | // by generation time: | |
58 | // A1...An B1...Bm C1...Ct | |
59 | // where A1 is the newest and Ct is the oldest, and we are going to compact | |
60 | // B1...Bm, we calculate the total size of all the files as total_size, as | |
61 | // well as the total size of C1...Ct as total_C, the compaction output file | |
62 | // will be compressed iff | |
63 | // total_C / total_size < this percentage | |
64 | // Default: -1 | |
65 | int compression_size_percent; | |
66 | ||
67 | // The algorithm used to stop picking files into a single compaction run | |
68 | // Default: kCompactionStopStyleTotalSize | |
69 | CompactionStopStyle stop_style; | |
70 | ||
71 | // Option to optimize the universal multi level compaction by enabling | |
72 | // trivial move for non overlapping files. | |
73 | // Default: false | |
74 | bool allow_trivial_move; | |
75 | ||
76 | // Default set of parameters | |
77 | CompactionOptionsUniversal() | |
78 | : size_ratio(1), | |
79 | min_merge_width(2), | |
80 | max_merge_width(UINT_MAX), | |
81 | max_size_amplification_percent(200), | |
82 | compression_size_percent(-1), | |
83 | stop_style(kCompactionStopStyleTotalSize), | |
84 | allow_trivial_move(false) {} | |
85 | }; | |
86 | ||
87 | } // namespace rocksdb |