Josh Kang
f897c1b2ef
Summary: Add tracking of uniform index blocks as a table property (`num_uniform_blocks`). When `uniform_cv_threshold` is set, the block builder detects uniformly distributed keys via coefficient of variation of key gaps. This information is now surfaced end-to-end: from block building through index builders to SST table properties. ## Key changes - **BlockBuilder**: Persist the uniformity result from `ScanForUniformity()` as a member (`is_uniform_`) exposed via `IsUniform()`, rather than a local variable discarded after `Finish()`. - **Index builders**: All three index builder types (`ShortenedIndexBuilder`, `HashIndexBuilder`, `PartitionedIndexBuilder`) implement `NumUniformIndexBlocks()`. For partitioned indexes, the count accumulates across partition `Finish()` calls. - **Table property serialization**: Added `TablePropertiesNames::kNumUniformBlocks` (`"rocksdb.num.uniform.blocks"`) with full serialization/deserialization support. Without this, the property was computed in memory but never persisted to SST files. - **Table property aggregation**: `num_uniform_blocks` included in `Add()` and `GetAggregatablePropertiesAsMap()` for correct cross-SST aggregation. Pull Request resolved: https://github.com/facebook/rocksdb/pull/14513 Test Plan: - **Unit tests**: `block_test` (7504 passed), `table_test` (6917 passed), `table_properties_collector_test` (8 passed). - **End-to-end verification via db_bench + sst_dump**: - Positive: `./db_bench --benchmarks=fillseq,compact --num=10000 --uniform_cv_threshold=0.2 --index_shortening_mode=0 --compression_type=none` produces SST with `# uniform blocks: 1`. - Negative: Same with `--uniform_cv_threshold=-1` (disabled) produces `# uniform blocks: 0`. Reviewed By: xingbowang Differential Revision: D98343170 Pulled By: joshkang97 fbshipit-source-id: ed08e83b2dcfb70f074bfb0f7bb5c31d75dc6da9
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.