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author | Pieter Wuille <pieter.wuille@gmail.com> | 2017-06-09 19:24:30 -0700 |
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committer | Pieter Wuille <pieter.wuille@gmail.com> | 2017-06-09 19:24:30 -0700 |
commit | cf44e4ca7762742c6c3154447b40869ec9d041db (patch) | |
tree | d5a89851da0a8ab07c40966ac137f4e299c80927 /README.md | |
parent | 634ad517037b319147816f1d112b066528e1724a (diff) | |
download | bitcoin-cf44e4ca7762742c6c3154447b40869ec9d041db.tar.xz |
Squashed 'src/leveldb/' changes from a31c8aa40..196962ff0
196962ff0 Add AcceleratedCRC32C to port_win.h
1bdf1c34c Merge upstream LevelDB v1.20
d31721eb0 Merge #17: Fixed file sharing errors
fecd44902 Fixed file sharing error in Win32Env::GetFileSize(), Win32SequentialFile::_Init(), Win32RandomAccessFile::_Init() Fixed error checking in Win32SequentialFile::_Init()
5b7510f1b Merge #14: Merge upstream LevelDB 1.19
0d969fd57 Merge #16: [LevelDB] Do no crash if filesystem can't fsync
c8c029b5b [LevelDB] Do no crash if filesystem can't fsync
a53934a3a Increase leveldb version to 1.20.
f3f139737 Separate Env tests from PosixEnv tests.
eb4f0972f leveldb: Fix compilation warnings in port_posix_sse.cc on x86 (32-bit).
d0883b600 Fixed path to doc file: index.md.
7fa20948d Convert documentation to markdown.
ea175e28f Implement support for Intel crc32 instruction (SSE 4.2)
95cd743e5 Including <limits> for std::numeric_limits.
646c3588d Limit the number of read-only files the POSIX Env will have open.
d40bc3fa5 Merge #13: Typo
ebbd772d3 Typo
a2fb086d0 Add option for max file size. The currend hard-coded value of 2M is inefficient in colossus.
git-subtree-dir: src/leveldb
git-subtree-split: 196962ff01c39b4705d8117df5c3f8c205349950
Diffstat (limited to 'README.md')
-rw-r--r-- | README.md | 25 |
1 files changed, 13 insertions, 12 deletions
@@ -16,7 +16,7 @@ Authors: Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com) * External activity (file system operations etc.) is relayed through a virtual interface so users can customize the operating system interactions. # Documentation - [LevelDB library documentation](https://rawgit.com/google/leveldb/master/doc/index.html) is online and bundled with the source code. + [LevelDB library documentation](https://github.com/google/leveldb/blob/master/doc/index.md) is online and bundled with the source code. # Limitations @@ -113,29 +113,30 @@ by the one or two disk seeks needed to fetch the data from disk. Write performance will be mostly unaffected by whether or not the working set fits in memory. - readrandom : 16.677 micros/op; (approximately 60,000 reads per second) - readseq : 0.476 micros/op; 232.3 MB/s - readreverse : 0.724 micros/op; 152.9 MB/s + readrandom : 16.677 micros/op; (approximately 60,000 reads per second) + readseq : 0.476 micros/op; 232.3 MB/s + readreverse : 0.724 micros/op; 152.9 MB/s LevelDB compacts its underlying storage data in the background to improve read performance. The results listed above were done immediately after a lot of random writes. The results after compactions (which are usually triggered automatically) are better. - readrandom : 11.602 micros/op; (approximately 85,000 reads per second) - readseq : 0.423 micros/op; 261.8 MB/s - readreverse : 0.663 micros/op; 166.9 MB/s + readrandom : 11.602 micros/op; (approximately 85,000 reads per second) + readseq : 0.423 micros/op; 261.8 MB/s + readreverse : 0.663 micros/op; 166.9 MB/s Some of the high cost of reads comes from repeated decompression of blocks read from disk. If we supply enough cache to the leveldb so it can hold the uncompressed blocks in memory, the read performance improves again: - readrandom : 9.775 micros/op; (approximately 100,000 reads per second before compaction) - readrandom : 5.215 micros/op; (approximately 190,000 reads per second after compaction) + readrandom : 9.775 micros/op; (approximately 100,000 reads per second before compaction) + readrandom : 5.215 micros/op; (approximately 190,000 reads per second after compaction) ## Repository contents -See doc/index.html for more explanation. See doc/impl.html for a brief overview of the implementation. +See [doc/index.md](doc/index.md) for more explanation. See +[doc/impl.md](doc/impl.md) for a brief overview of the implementation. The public interface is in include/*.h. Callers should not include or rely on the details of any other header files in this package. Those @@ -148,7 +149,7 @@ Guide to header files: * **include/options.h**: Control over the behavior of an entire database, and also control over the behavior of individual reads and writes. -* **include/comparator.h**: Abstraction for user-specified comparison function. +* **include/comparator.h**: Abstraction for user-specified comparison function. If you want just bytewise comparison of keys, you can use the default comparator, but clients can write their own comparator implementations if they want custom ordering (e.g. to handle different character encodings, etc.) @@ -165,7 +166,7 @@ length into some other byte array. * **include/status.h**: Status is returned from many of the public interfaces and is used to report success and various kinds of errors. -* **include/env.h**: +* **include/env.h**: Abstraction of the OS environment. A posix implementation of this interface is in util/env_posix.cc |