Public API Changes

• To reduce risk of ODR violations or similar, ROCKSDB_USING_THREAD_STATUS has been removed from public headers and replaced with static const bool ThreadStatus::kEnabled. Some other uses of conditional compilation have been removed from public API headers to reduce risk of ODR violations or other issues.

Behavior Changes

• PosixWritableFile now repositions the seek pointer to the new end of file after a call to Truncate.
• Updated standalone range deletion L0 file compaction behavior to avoid compacting with any newer L0 files (which is expensive and not useful).

Bug Fixes

• Fix a bug where compaction with range deletion can persist kTypeMaxValid in MANIFEST as file metadata. kTypeMaxValid is not supposed to be persisted and can change as new value types are introduced. This can cause a forward compatibility issue where older versions of RocksDB don't recognize kTypeMaxValid from newer versions. A new placeholder value type kTypeTruncatedRangeDeletionSentinel is also introduced to replace kTypeMaxValid when reading existing SST files' metadata from MANIFEST. This allows us to strengthen some checks to avoid using kTypeMaxValid in the future.
• Fixed a bug where DB::GetSortedWalFiles() could hang when waiting for a purge operation that found nothing to do (potentially triggered by iterator release, flush, compaction, etc.).
• Fixed a bug in MultiScan where max_sequential_skip_in_iterations could cause the iterator to seek backward to already-unpinned blocks when the same user key spans multiple data blocks, leading to assertion failures or seg fault.
• Fixed a bug for WAL_ttl_seconds > 0 use cases where the newest archived WAL files could be incorrectly deleted when the system clock moved backwards.

Performance Improvements

• Added optimization that allowed for the asynchronous prefetching of all data outlined in a multiscan iterator. This optimization was applied to the level iterator, which prefetches all data through each of the block-based iterators.