3bfd3ed2f3
Summary: This does not add any new public APIs or published functionality, but adds the ability to read and use (and in tests, write) backups with a new meta file schema, based on the old schema but not forward-compatible (before this change). The new schema enables some capabilities not in the old: * Explicit versioning, so that users get clean error messages the next time we want to break forward compatibility. * Ignoring unrecognized fields (with warning), so that new non-critical features can be added without breaking forward compatibility. * Rejecting future "non-ignorable" fields, so that new features critical to some use-cases could potentially be added outside of linear schema versions, with broken forward compatibility. * Fields at the end of the meta file, such as for checksum of the meta file's contents (up to that point) * New optional 'size' field for each file, which is checked when present * Optionally omitting 'crc32' field, so that we aren't required to have a crc32c checksum for files to take a backup. (E.g. to support backup via hard links and to better support file custom checksums.) Because we do not have a JSON parser and to share code, the new schema is simply derived from the old schema. BackupEngine code is updated to allow missing checksums in some places, and to make that easier, `has_checksum` and `verify_checksum_after_work` are eliminated. Empty `checksum_hex` indicates checksum is unknown. I'm not too afraid of regressing on data integrity, because (a) we have pretty good test coverage of corruption detection in backups, and (b) we are increasingly relying on the DB itself for data integrity rather than it being an exclusive feature of backups. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8069 Test Plan: new unit tests, added to crash test (some local run with boosted backup probability) Reviewed By: ajkr Differential Revision: D27139824 Pulled By: pdillinger fbshipit-source-id: 9e0e4decfb42bb84783d64d2d246456d97e8e8c5
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 especially 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/ and https://rocksdb.slack.com/
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.