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Diffstat (limited to 'src/leveldb/README.md')
| -rw-r--r-- | src/leveldb/README.md | 25 |
1 files changed, 13 insertions, 12 deletions
diff --git a/src/leveldb/README.md b/src/leveldb/README.md index c75b185e0e..a010c50858 100644 --- a/src/leveldb/README.md +++ b/src/leveldb/README.md @@ -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 |