Revision d3d20dcdca9dc79d893a03dfa611fb1055c28f96 authored by Sagar Vemuri on 11 April 2019, 02:24:25 UTC, committed by Facebook Github Bot on 11 April 2019, 02:31:18 UTC
Summary: Introducing Periodic Compactions. This feature allows all the files in a CF to be periodically compacted. It could help in catching any corruptions that could creep into the DB proactively as every file is constantly getting re-compacted. And also, of course, it helps to cleanup data older than certain threshold. - Introduced a new option `periodic_compaction_time` to control how long a file can live without being compacted in a CF. - This works across all levels. - The files are put in the same level after going through the compaction. (Related files in the same level are picked up as `ExpandInputstoCleanCut` is used). - Compaction filters, if any, are invoked as usual. - A new table property, `file_creation_time`, is introduced to implement this feature. This property is set to the time at which the SST file was created (and that time is given by the underlying Env/OS). This feature can be enabled on its own, or in conjunction with `ttl`. It is possible to set a different time threshold for the bottom level when used in conjunction with ttl. Since `ttl` works only on 0 to last but one levels, you could set `ttl` to, say, 1 day, and `periodic_compaction_time` to, say, 7 days. Since `ttl < periodic_compaction_time` all files in last but one levels keep getting picked up based on ttl, and almost never based on periodic_compaction_time. The files in the bottom level get picked up for compaction based on `periodic_compaction_time`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5166 Differential Revision: D14884441 Pulled By: sagar0 fbshipit-source-id: 408426cbacb409c06386a98632dcf90bfa1bda47
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README.md
## RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
[](https://travis-ci.org/facebook/rocksdb)
[](https://ci.appveyor.com/project/Facebook/rocksdb/branch/master)
[](http://140.211.168.68:8080/job/Rocksdb)
RocksDB is developed and maintained by Facebook Database Engineering Team.
It is built on earlier work on [LevelDB](https://github.com/google/leveldb) by Sanjay Ghemawat (sanjay@google.com)
and Jeff Dean (jeff@google.com)
This code is a library that forms the core building block for a fast
key value server, especially suited for storing data on flash drives.
It has a Log-Structured-Merge-Database (LSM) design with flexible tradeoffs
between Write-Amplification-Factor (WAF), Read-Amplification-Factor (RAF)
and Space-Amplification-Factor (SAF). It has multi-threaded compactions,
making it specially suitable for storing multiple terabytes of data in a
single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/master/examples
See the [github wiki](https://github.com/facebook/rocksdb/wiki) for more explanation.
The public interface is in `include/`. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Design discussions are conducted in https://www.facebook.com/groups/rocksdb.dev/
## License
RocksDB is dual-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). You may select, at your option, one of the above-listed licenses.
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