ec70fea4c4
Summary: When seek target is a merge key (`kTypeMerge`), `DBIter::FindNextUserEntry()` advances the underlying iterator _past_ the current key (`saved_key_`); see `MergeValuesNewToOld()`. However, `FindPrevUserKey()` assumes that `iter_` points to an entry with the same user key as `saved_key_`. As a result, `it->Seek(key) && it->Prev()` can cause the iterator to be positioned at the _next_, instead of the previous, entry (new test, written by @lovro, reproduces the bug). This diff changes `FindPrevUserKey()` to also skip keys that are _greater_ than `saved_key_`. Test Plan: db_test Reviewers: igor, sdong Reviewed By: sdong Subscribers: leveldb, dhruba, lovro Differential Revision: https://reviews.facebook.net/D40791
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/