Xingbo Wang
c47e35395b
Summary: T263957043 reproduces in whitebox crash testing when DBIter converts a run of point deletes into a range tombstone while reading with an older user-defined timestamp. The scan can observe an older delete for the boundary keys but miss newer live versions of the same keys and interior keys, so the synthesized tombstone is based on partial visibility and later hides valid max-timestamp reads. ## Problem Read-path range tombstone conversion (`min_tombstones_for_range_conversion`) assumes the scan observes all interior live keys between the start and end of a contiguous delete run. With user-defined timestamps, a read at an older timestamp can see deletes but miss newer Puts for the same keys. The synthesized range tombstone then incorrectly covers those newer versions, causing data loss on subsequent max-timestamp reads. ## Fix Gate read-path range conversion on full timestamp visibility. The optimization is now only enabled when: 1. There is no `table_filter` (existing guard — SSTs hidden by filter can break the contiguity assumption) 2. There is no `iter_start_ts` (time-travel scans see a subset of versions) 3. Either no read timestamp is set, or the read timestamp is the max timestamp (all `0xff` bytes) This is done via a new helper `HasFullTimestampVisibility()` checked at `DBIter` construction time. ## Test Changes - Updated all existing UDT test variants in `ReadPathRangeTombstoneTest` to read at max timestamp so the optimization remains covered where it is valid. - Added `UDTOlderTimestampDisablesInsertion`: a regression test that writes at ts=1, deletes at ts=2, writes again at ts=3, then reads at ts=2. Verifies no range tombstone is synthesized and a subsequent max-timestamp read still sees all live values. ## Validation - `make -j192 db_iterator_test` - `./db_iterator_test --gtest_filter='*ReadPathRangeTombstoneTest*'` - `./db_iterator_test --gtest_filter='*UDTOlderTimestampDisablesInsertion*' --gtest_repeat=5` - Reran the original whitebox crash-test seed from T263957043 against the patched tree; crash-recovery verification passed Pull Request resolved: https://github.com/facebook/rocksdb/pull/14595 Reviewed By: joshkang97 Differential Revision: D100235999 Pulled By: xingbowang fbshipit-source-id: 7a287f3c7fdc47428fda0ab89eedd5d43f663985
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.