10984e8c26
Summary: There was a subtle design/contract bug in the previous version of range filtering in experimental.h If someone implemented a key segments extractor with "all or nothing" fixed size segments, that could result in unsafe range filtering. For example, with two segments of width 3: ``` x = 0x|12 34 56|78 9A 00| y = 0x|12 34 56||78 9B z = 0x|12 34 56|78 9C 00| ``` Segment 1 of y (empty) is out of order with segment 1 of x and z. I have re-worked the contract to make it clear what does work, and implemented a standard extractor for fixed-size segments, CappedKeySegmentsExtractor. The safe approach for filtering is to consume as much as is available for a segment in the case of a short key. I have also added support for min-max filtering with reverse byte-wise comparator, which is probably the 2nd most common comparator for RocksDB users (because of MySQL). It might seem that a min-max filter doesn't care about forward or reverse ordering, but it does when trying to determine whether in input range from segment values v1 to v2, where it so happens that v2 is byte-wise less than v1, is an empty forward interval or a non-empty reverse interval. At least in the current setup, we don't have that context. A new unit test (with some refactoring) tests CappedKeySegmentsExtractor, reverse byte-wise comparator, and the corresponding min-max filter. I have also (contractually / mathematically) generalized the framework to comparators other than the byte-wise comparator, and made other generalizations to make the extractor limitations more explicitly connected to the particular filters and filtering used--at least in description. Pull Request resolved: https://github.com/facebook/rocksdb/pull/13005 Test Plan: added unit tests as described Reviewed By: jowlyzhang Differential Revision: D62769784 Pulled By: pdillinger fbshipit-source-id: 0d41f0d0273586bdad55e4aa30381ebc861f7044 |
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README.md
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/main/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.
Questions and discussions are welcome on the RocksDB Developers Public Facebook group and email list on Google Groups.
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.