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Summary: **Context/Summary:** During prefix scan, prefetched data blocks containing keys not in the same prefix as the `Seek()`'s key will be wasted when `ReadOptions::prefix_same_as_start = true` since they won't be returned to the user. This PR is to exclude those data blocks from being prefetched in a similar manner like trimming according to `ReadOptions::iterate_upper_bound`. Bonus: refactoring to some existing prefetch test so they are easier to extend and read Pull Request resolved: https://github.com/facebook/rocksdb/pull/13040 Test Plan: - New UT, integration to existing UTs - Benchmark to ensure no regression from CPU due to more trimming logic ``` // Build DB with one sorted run under the same prefix ./db_bench --benchmarks=fillrandom --prefix_size=3 --keys_per_prefix=5000000 --num=5000000 --db=/dev/shm/db_bench --disable_auto_compactions=1 ``` ``` // Augment the existing db bench to call `Seek()` instead of `SeekToFirst()` in `void ReadSequential(){..}` to trigger the logic in this PR +++ b/tools/db_bench_tool.cc @@ -5900,7 +5900,12 @@ class Benchmark { Iterator* iter = db->NewIterator(options); int64_t i = 0; int64_t bytes = 0; - for (iter->SeekToFirst(); i < reads_ && iter->Valid(); iter->Next()) { + + iter->SeekToFirst(); + assert(iter->status().ok() && iter->Valid()); + auto prefix = prefix_extractor_->Transform(iter->key()); + + for (iter->Seek(prefix); i < reads_ && iter->Valid(); iter->Next()) { bytes += iter->key().size() + iter->value().size(); thread->stats.FinishedOps(nullptr, db, 1, kRead); ++i; : ``` ``` // Compare prefix scan performance ./db_bench --benchmarks=readseq[-X20] --prefix_size=3 --prefix_same_as_start=1 --auto_readahead_size=1 --cache_size=1 --use_existing_db=1 --db=/dev/shm/db_bench --disable_auto_compactions=1 // Before PR readseq [AVG 20 runs] : 2449011 (± 50238) ops/sec; 270.9 (± 5.6) MB/sec readseq [MEDIAN 20 runs] : 2499167 ops/sec; 276.5 MB/sec // After PR (regress 0.4 %) readseq [AVG 20 runs] : 2439098 (± 42931) ops/sec; 269.8 (± 4.7) MB/sec readseq [MEDIAN 20 runs] : 2460859 ops/sec; 272.2 MB/sec ``` - Stress test: randomly set `prefix_same_as_start` in `TestPrefixScan()`. Run below for a while ``` python3 tools/db_crashtest.py --simple blackbox --prefix_size=5 --prefixpercent=65 --WAL_size_limit_MB=1 --WAL_ttl_seconds=0 --acquire_snapshot_one_in=10000 --adm_policy=1 --advise_random_on_open=1 --allow_data_in_errors=True --allow_fallocate=0 --async_io=0 --avoid_flush_during_recovery=1 --avoid_flush_during_shutdown=1 --avoid_unnecessary_blocking_io=0 --backup_max_size=104857600 --backup_one_in=1000 --batch_protection_bytes_per_key=8 --bgerror_resume_retry_interval=100 --block_align=1 --block_protection_bytes_per_key=4 --block_size=16384 --bloom_before_level=-1 --bloom_bits=3 --bottommost_compression_type=none --bottommost_file_compaction_delay=3600 --bytes_per_sync=262144 --cache_index_and_filter_blocks=0 --cache_index_and_filter_blocks_with_high_priority=0 --cache_size=33554432 --cache_type=lru_cache --charge_compression_dictionary_building_buffer=1 --charge_file_metadata=0 --charge_filter_construction=0 --charge_table_reader=0 --check_multiget_consistency=0 --check_multiget_entity_consistency=0 --checkpoint_one_in=10000 --checksum_type=kxxHash --clear_column_family_one_in=0 --compact_files_one_in=1000 --compact_range_one_in=1000 --compaction_pri=4 --compaction_readahead_size=0 --compaction_style=2 --compaction_ttl=0 --compress_format_version=2 --compressed_secondary_cache_size=16777216 --compression_checksum=0 --compression_max_dict_buffer_bytes=0 --compression_max_dict_bytes=0 --compression_parallel_threads=1 --compression_type=none --compression_use_zstd_dict_trainer=1 --compression_zstd_max_train_bytes=0 --continuous_verification_interval=0 --daily_offpeak_time_utc= --data_block_index_type=0 --db_write_buffer_size=8388608 --decouple_partitioned_filters=1 --default_temperature=kCold --default_write_temperature=kWarm --delete_obsolete_files_period_micros=21600000000 --delpercent=4 --delrangepercent=1 --destroy_db_initially=1 --detect_filter_construct_corruption=0 --disable_file_deletions_one_in=10000 --disable_manual_compaction_one_in=1000000 --disable_wal=0 --dump_malloc_stats=1 --enable_checksum_handoff=0 --enable_compaction_filter=0 --enable_custom_split_merge=1 --enable_do_not_compress_roles=1 --enable_index_compression=1 --enable_memtable_insert_with_hint_prefix_extractor=0 --enable_pipelined_write=1 --enable_sst_partitioner_factory=0 --enable_thread_tracking=1 --enable_write_thread_adaptive_yield=0 --error_recovery_with_no_fault_injection=0 --exclude_wal_from_write_fault_injection=1 --fail_if_options_file_error=0 --fifo_allow_compaction=1 --file_checksum_impl=big --fill_cache=0 --flush_one_in=1000000 --format_version=6 --get_all_column_family_metadata_one_in=10000 --get_current_wal_file_one_in=0 --get_live_files_apis_one_in=10000 --get_properties_of_all_tables_one_in=1000000 --get_property_one_in=1000000 --get_sorted_wal_files_one_in=0 --hard_pending_compaction_bytes_limit=274877906944 --high_pri_pool_ratio=0 --index_block_restart_interval=15 --index_shortening=2 --index_type=2 --ingest_external_file_one_in=0 --inplace_update_support=0 --iterpercent=10 --key_len_percent_dist=1,30,69 --key_may_exist_one_in=100000 --last_level_temperature=kUnknown --level_compaction_dynamic_level_bytes=0 --lock_wal_one_in=1000000 --log2_keys_per_lock=10 --log_file_time_to_roll=0 --log_readahead_size=0 --long_running_snapshots=0 --low_pri_pool_ratio=0.5 --lowest_used_cache_tier=2 --manifest_preallocation_size=5120 --manual_wal_flush_one_in=1000 --mark_for_compaction_one_file_in=10 --max_background_compactions=20 --max_bytes_for_level_base=10485760 --max_key=1000 --max_key_len=3 --max_log_file_size=1048576 --max_manifest_file_size=1073741824 --max_sequential_skip_in_iterations=8 --max_total_wal_size=0 --max_write_batch_group_size_bytes=16777216 --max_write_buffer_number=10 --max_write_buffer_size_to_maintain=4194304 --memtable_insert_hint_per_batch=1 --memtable_max_range_deletions=0 --memtable_prefix_bloom_size_ratio=0.01 --memtable_protection_bytes_per_key=2 --memtable_whole_key_filtering=1 --memtablerep=skip_list --metadata_charge_policy=1 --metadata_read_fault_one_in=32 --metadata_write_fault_one_in=0 --min_write_buffer_number_to_merge=2 --mmap_read=0 --mock_direct_io=True --nooverwritepercent=1 --open_files=-1 --open_metadata_read_fault_one_in=0 --open_metadata_write_fault_one_in=8 --open_read_fault_one_in=0 --open_write_fault_one_in=0 --ops_per_thread=40000 --optimize_filters_for_hits=0 --optimize_filters_for_memory=1 --optimize_multiget_for_io=1 --paranoid_file_checks=1 --paranoid_memory_checks=0 --partition_filters=0 --partition_pinning=3 --pause_background_one_in=10000 --periodic_compaction_seconds=0 --prepopulate_block_cache=1 --preserve_internal_time_seconds=0 --progress_reports=0 --promote_l0_one_in=0 --read_amp_bytes_per_bit=0 --read_fault_one_in=32 --readpercent=10 --recycle_log_file_num=0 --reopen=0 --report_bg_io_stats=0 --reset_stats_one_in=1000000 --sample_for_compression=5 --secondary_cache_fault_one_in=0 --secondary_cache_uri= --skip_stats_update_on_db_open=0 --snapshot_hold_ops=100000 --soft_pending_compaction_bytes_limit=1048576 --sqfc_name=foo --sqfc_version=2 --sst_file_manager_bytes_per_sec=104857600 --sst_file_manager_bytes_per_truncate=1048576 --stats_dump_period_sec=10 --stats_history_buffer_size=1048576 --strict_bytes_per_sync=1 --subcompactions=4 --sync=0 --sync_fault_injection=1 --table_cache_numshardbits=-1 --target_file_size_base=524288 --target_file_size_multiplier=2 --test_batches_snapshots=0 --top_level_index_pinning=0 --uncache_aggressiveness=1 --universal_max_read_amp=10 --unpartitioned_pinning=0 --use_adaptive_mutex=1 --use_adaptive_mutex_lru=1 --use_attribute_group=0 --use_delta_encoding=0 --use_direct_io_for_flush_and_compaction=0 --use_direct_reads=1 --use_full_merge_v1=1 --use_get_entity=0 --use_merge=1 --use_multi_cf_iterator=1 --use_multi_get_entity=0 --use_multiget=1 --use_put_entity_one_in=0 --use_sqfc_for_range_queries=1 --use_timed_put_one_in=0 --use_write_buffer_manager=1 --user_timestamp_size=0 --value_size_mult=32 --verification_only=0 --verify_checksum=1 --verify_checksum_one_in=1000 --verify_compression=0 --verify_db_one_in=100000 --verify_file_checksums_one_in=1000 --verify_iterator_with_expected_state_one_in=5 --verify_sst_unique_id_in_manifest=1 --wal_bytes_per_sync=0 --wal_compression=none --write_buffer_size=1048576 --write_dbid_to_manifest=1 --write_fault_one_in=1000 --writepercent=10 ``` Reviewed By: anand1976 Differential Revision: D64367065 Pulled By: hx235 fbshipit-source-id: 5750c05ccc835c3e9dc81c961b76deaf30bd23c2 |
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|---|---|---|
| .. | ||
| behavior_changes | ||
| bug_fixes | ||
| new_features | ||
| performance_improvements | ||
| public_api_changes | ||
| add.sh | ||
| README.txt | ||
| release.sh | ||
Adding release notes -------------------- When adding release notes for the next release, add a file to one of these directories: unreleased_history/new_features unreleased_history/behavior_changes unreleased_history/public_api_changes unreleased_history/bug_fixes with a unique name that makes sense for your change, preferably using the .md extension for syntax highlighting. There is a script to help, as in $ unreleased_history/add.sh unreleased_history/bug_fixes/crash_in_feature.md or simply $ unreleased_history/add.sh will take you through some prompts. The file should usually contain one line of markdown, and "* " is not required, as it will automatically be inserted later if not included at the start of the first line in the file. Extra newlines or missing trailing newlines will also be corrected. The only times release notes should be added directly to HISTORY are if * A release is being amended or corrected after it is already "cut" but not tagged, which should be rare. * A single commit contains a noteworthy change and a patch release version bump Ordering of entries ------------------- Within each group, entries will be included using ls sort order, so important entries could start their file name with a small three digit number like 100pretty_important.md. The ordering of groups such as new_features vs. public_api_changes is hard-coded in unreleased_history/release.sh Updating HISTORY.md with release notes -------------------------------------- The script unreleased_history/release.sh does this. Run the script before updating version.h to the next development release, so that the script will pick up the version being released. You might want to start with $ DRY_RUN=1 unreleased_history/release.sh | less to check for problems and preview the output. Then run $ unreleased_history/release.sh which will git rm some files and modify HISTORY.md. You still need to commit the changes, or revert with the command reported in the output. Why not update HISTORY.md directly? ----------------------------------- First, it was common to hit unnecessary merge conflicts when adding entries to HISTORY.md, which slowed development. Second, when a PR was opened before a release cut and landed after the release cut, it was easy to add the HISTORY entry to the wrong version's history. This new setup completely fixes both of those issues, with perhaps slightly more initial work to create each entry. There is also now an extra step in using `git blame` to map a release note to its source code implementation, but that is a relatively rare operation.