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This change impacts only non-buffered I/O on Windows. Currently, there is a buffer per RandomAccessFile instance that is protected by a lock. The reason we maintain the buffer is non-buffered I/O requires an aligned buffer to work. XPerf traces demonstrate that we accumulate a considerable wait time while waiting for that lock. This change enables to set random access buffer size to zero which would indicate a per request allocation. We are expecting that allocation expense would be much less than I/O costs plus wait time due to the fact that the memory heap would tend to re-use page aligned allocations especially with the use of Jemalloc. This change does not affect buffer use as a read_ahead_buffer for compaction purposes.
RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
RocksDB is developed and maintained by Facebook Database Engineering Team. It is built on earlier work on 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 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/