3469d60fcc
Summary: With Ribbon filter work and possible variance in actual bits per key (or prefix; general term "entry") to achieve certain FP rates, I've received a request to be able to track actual bits per key in generated filters. This change adds a num_filter_entries table property, which can be combined with filter_size to get bits per key (entry). This can vary from num_entries in at least these ways: * Different versions of same key are only counted once in filters. * With prefix filters, several user keys map to the same filter entry. * A single filter can include both prefixes and user keys. Note that FilterBlockBuilder::NumAdded() didn't do anything useful except distinguish empty from non-empty. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8323 Test Plan: basic unit test included, others updated Reviewed By: jay-zhuang Differential Revision: D28596210 Pulled By: pdillinger fbshipit-source-id: 529a111f3c84501e5a470bc84705e436ee68c376
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.