17edc82a4b
Summary: The CollapsedRangeDelMap was entirely mishandling tombstones at the same sequence number when the tombstones did not have identical start and end keys. Such tombstones are common since 90fc40690, which causes tombstones to be split during compactions. For example, if the tombstone [a, c) @ 1 lies across a compaction boundary at b, it will be split into [a, b) @ 1 and [b, c) @ 1. Without this patch, the collapsed range deletion map would look like this: a -> 1 b -> 1 c -> 0 Notice how the b -> 1 entry is redundant. When the tombstones overlap, the problem is even worse. Consider tombstones [a, c) @ 1 and [b, d) @ 1, which produces this map without this patch: a -> 1 b -> 1 c -> 0 d -> 0 This map is corrupt, as a map can never contain adjacent sentinel (zero) entries. When the iterator advances from b to c, it will notice that c is a sentinel enty and skip to d--but d is also a sentinel entry! Asking what tombstone this iterator points to will trigger an assertion, as it is not pointing to a valid tombstone. /cc ajkr Pull Request resolved: https://github.com/facebook/rocksdb/pull/4424 Differential Revision: D10039248 Pulled By: abhimadan fbshipit-source-id: 6d737c1e88d60e80cf27286726627ba44463e7f4
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/
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.