Summary:
before this PR, if there is a range tombstone-only file generated in penultimate level, it is marked the `last_level_temperature`. This PR fixes this issue.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10972
Test Plan: added unit test for this scenario.
Reviewed By: ajkr
Differential Revision: D41449215
Pulled By: cbi42
fbshipit-source-id: 1e06b5ae3bc0183db2991a45965a9807a7e8be0c
Summary:
We were not resetting it in non-debug mode so it could be true once and then stay true for future keys where it should be false. This PR adds the reset logic.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10967
Test Plan:
- built `db_bench` with DEBUG_LEVEL=0
- ran benchmark: `TEST_TMPDIR=/dev/shm/prefix ./db_bench -benchmarks=fillrandom -compaction_style=1 -preserve_internal_time_seconds=100 -preclude_last_level_data_seconds=10 -write_buffer_size=1048576 -target_file_size_base=1048576 -subcompactions=8 -duration=120`
- compared "output_to_penultimate_level: X bytes + last: Y bytes" lines in LOG output
- Before this fix, Y was always zero
- After this fix, Y gradually increased throughout the benchmark
Reviewed By: riversand963
Differential Revision: D41417726
Pulled By: ajkr
fbshipit-source-id: ace1e9a289e751a5b0c2fbaa8addd4eda5525329
Summary:
This PR implements the originally disabled `Merge()` APIs when user-defined timestamp is enabled.
Simplest usage:
```cpp
// assume string append merge op is used with '.' as delimiter.
// ts1 < ts2
db->Put(WriteOptions(), "key", ts1, "v0");
db->Merge(WriteOptions(), "key", ts2, "1");
ReadOptions ro;
ro.timestamp = &ts2;
db->Get(ro, "key", &value);
ASSERT_EQ("v0.1", value);
```
Some code comments are added for clarity.
Note: support for timestamp in `DB::GetMergeOperands()` will be done in a follow-up PR.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10819
Test Plan: make check
Reviewed By: ltamasi
Differential Revision: D40603195
Pulled By: riversand963
fbshipit-source-id: f96d6f183258f3392d80377025529f7660503013
Summary:
**Context:**
Same as https://github.com/facebook/rocksdb/pull/5958#issue-511150930 but apply the fix to FIFO Compaction case
Repro:
```
COERCE_CONTEXT_SWICH=1 make -j56 db_stress
./db_stress --acquire_snapshot_one_in=0 --adaptive_readahead=0 --allow_data_in_errors=True --async_io=1 --avoid_flush_during_recovery=0 --avoid_unnecessary_blocking_io=0 --backup_max_size=104857600 --backup_one_in=0 --batch_protection_bytes_per_key=0 --block_size=16384 --bloom_bits=18 --bottommost_compression_type=disable --bytes_per_sync=262144 --cache_index_and_filter_blocks=0 --cache_size=8388608 --cache_type=lru_cache --charge_compression_dictionary_building_buffer=0 --charge_file_metadata=1 --charge_filter_construction=1 --charge_table_reader=1 --checkpoint_one_in=0 --checksum_type=kCRC32c --clear_column_family_one_in=0 --column_families=1 --compact_files_one_in=0 --compact_range_one_in=1000 --compaction_pri=3 --open_files=-1 --compaction_style=2 --fifo_allow_compaction=1 --compaction_ttl=0 --compression_max_dict_buffer_bytes=8388607 --compression_max_dict_bytes=16384 --compression_parallel_threads=1 --compression_type=zlib --compression_use_zstd_dict_trainer=1 --compression_zstd_max_train_bytes=0 --continuous_verification_interval=0 --data_block_index_type=0 --db=/dev/shm/rocksdb_test0/rocksdb_crashtest_whitebox --db_write_buffer_size=8388608 --delpercent=4 --delrangepercent=1 --destroy_db_initially=1 --detect_filter_construct_corruption=0 --disable_wal=0 --enable_compaction_filter=0 --enable_pipelined_write=1 --fail_if_options_file_error=1 --file_checksum_impl=none --flush_one_in=1000 --format_version=5 --get_current_wal_file_one_in=0 --get_live_files_one_in=0 --get_property_one_in=0 --get_sorted_wal_files_one_in=0 --index_block_restart_interval=15 --index_type=3 --ingest_external_file_one_in=100 --initial_auto_readahead_size=0 --iterpercent=10 --key_len_percent_dist=1,30,69 --level_compaction_dynamic_level_bytes=True --log2_keys_per_lock=10 --long_running_snapshots=0 --mark_for_compaction_one_file_in=10 --max_auto_readahead_size=16384 --max_background_compactions=20 --max_bytes_for_level_base=10485760 --max_key=100000 --max_key_len=3 --max_manifest_file_size=1073741824 --max_write_batch_group_size_bytes=1048576 --max_write_buffer_number=3 --max_write_buffer_size_to_maintain=4194304 --memtable_prefix_bloom_size_ratio=0.5 --memtable_protection_bytes_per_key=1 --memtable_whole_key_filtering=1 --memtablerep=skip_list --mmap_read=1 --mock_direct_io=False --nooverwritepercent=1 --num_file_reads_for_auto_readahead=0 --num_levels=1 --open_metadata_write_fault_one_in=0 --open_read_fault_one_in=32 --open_write_fault_one_in=0 --ops_per_thread=200000 --optimize_filters_for_memory=0 --paranoid_file_checks=1 --partition_filters=0 --partition_pinning=1 --pause_background_one_in=0 --periodic_compaction_seconds=0 --prefix_size=8 --prefixpercent=5 --prepopulate_block_cache=0 --progress_reports=0 --read_fault_one_in=0 --readahead_size=16384 --readpercent=45 --recycle_log_file_num=1 --reopen=20 --ribbon_starting_level=999 --snapshot_hold_ops=1000 --sst_file_manager_bytes_per_sec=0 --sst_file_manager_bytes_per_truncate=0 --subcompactions=2 --sync=0 --sync_fault_injection=0 --target_file_size_base=524288 --target_file_size_multiplier=2 --test_batches_snapshots=0 --top_level_index_pinning=3 --unpartitioned_pinning=0 --use_direct_io_for_flush_and_compaction=0 --use_direct_reads=0 --use_full_merge_v1=1 --use_merge=0 --use_multiget=1 --user_timestamp_size=0 --value_size_mult=32 --verify_checksum=1 --verify_checksum_one_in=0 --verify_db_one_in=1000 --verify_sst_unique_id_in_manifest=1 --wal_bytes_per_sync=0 --wal_compression=zstd --write_buffer_size=524288 --write_dbid_to_manifest=0 --writepercent=35
put or merge error: Corruption: force_consistency_checks(DEBUG): VersionBuilder: L0 file https://github.com/facebook/rocksdb/issues/479 with seqno 23711 29070 vs. file https://github.com/facebook/rocksdb/issues/482 with seqno 27138 29049
```
**Summary:**
FIFO only does intra-L0 compaction in the following four cases. For other cases, FIFO drops data instead of compacting on data, which is irrelevant to the overlapping seqno issue we are solving.
- [FIFOCompactionPicker::PickSizeCompaction](https://github.com/facebook/rocksdb/blob/7.6.fb/db/compaction/compaction_picker_fifo.cc#L155) when `total size < compaction_options_fifo.max_table_files_size` and `compaction_options_fifo.allow_compaction == true`
- For this path, we simply reuse the fix in `FindIntraL0Compaction` https://github.com/facebook/rocksdb/pull/5958/files#diff-c261f77d6dd2134333c4a955c311cf4a196a08d3c2bb6ce24fd6801407877c89R56
- This path was not stress-tested at all. Therefore we covered `fifo.allow_compaction` in stress test to surface the overlapping seqno issue we are fixing here.
- [FIFOCompactionPicker::PickCompactionToWarm](https://github.com/facebook/rocksdb/blob/7.6.fb/db/compaction/compaction_picker_fifo.cc#L313) when `compaction_options_fifo.age_for_warm > 0`
- For this path, we simply replicate the idea in https://github.com/facebook/rocksdb/pull/5958#issue-511150930 and skip files of largest seqno greater than `earliest_mem_seqno`
- This path was not stress-tested at all. However covering `age_for_warm` option worths a separate PR to deal with db stress compatibility. Therefore we manually tested this path for this PR
- [FIFOCompactionPicker::CompactRange](https://github.com/facebook/rocksdb/blob/7.6.fb/db/compaction/compaction_picker_fifo.cc#L365) that ends up picking one of the above two compactions
- [CompactionPicker::CompactFiles](https://github.com/facebook/rocksdb/blob/7.6.fb/db/compaction/compaction_picker.cc#L378)
- Since `SanitizeCompactionInputFiles()` will be called [before](https://github.com/facebook/rocksdb/blob/7.6.fb/db/compaction/compaction_picker.h#L111-L113) `CompactionPicker::CompactFiles` , we simply replicate the idea in https://github.com/facebook/rocksdb/pull/5958#issue-511150930 in `SanitizeCompactionInputFiles()`. To simplify implementation, we return `Stats::Abort()` on encountering seqno-overlapped file when doing compaction to L0 instead of skipping the file and proceed with the compaction.
Some additional clean-up included in this PR:
- Renamed `earliest_memtable_seqno` to `earliest_mem_seqno` for consistent naming
- Added comment about `earliest_memtable_seqno` in related APIs
- Made parameter `earliest_memtable_seqno` constant and required
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10777
Test Plan:
- make check
- New unit test `TEST_P(DBCompactionTestFIFOCheckConsistencyWithParam, FlushAfterIntraL0CompactionWithIngestedFile)`corresponding to the above 4 cases, which will fail accordingly without the fix
- Regular CI stress run on this PR + stress test with aggressive value https://github.com/facebook/rocksdb/pull/10761 and on FIFO compaction only
Reviewed By: ajkr
Differential Revision: D40090485
Pulled By: hx235
fbshipit-source-id: 52624186952ee7109117788741aeeac86b624a4f
Summary:
Allow the last level only compaction able to output result to penultimate level if the penultimate level is empty. Which will also block the other compaction output to the penultimate level.
(it includes the PR https://github.com/facebook/rocksdb/issues/10829)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10822
Reviewed By: siying
Differential Revision: D40389180
Pulled By: jay-zhuang
fbshipit-source-id: 4e5dcdce307795b5e07b5dd1fa29dd75bb093bad
Summary:
When the `preclude_last_level_data_seconds` or
`preserve_internal_time_seconds` is smaller than 100 (seconds), no seqno->time information was recorded.
Also make sure all data will be compacted to the last level even if there's no write to record the time information.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10829
Test Plan: added unittest
Reviewed By: siying
Differential Revision: D40443934
Pulled By: jay-zhuang
fbshipit-source-id: 2ecf1361daf9f3e5c3385aee6dc924fa59e2813a
Summary:
FIFO compaction can theoretically open a DB with any compaction style.
However, the current code only allows FIFO compaction to open a DB with
a single level.
This PR relaxes the limitation of FIFO compaction and allows it to open a
DB with multiple levels. Below is the read / write / compaction behavior:
* The read behavior is untouched, and it works like a regular rocksdb instance.
* The write behavior is untouched as well. When a FIFO compacted DB
is opened with multiple levels, all new files will still be in level 0, and no files
will be moved to a different level.
* Compaction logic is extended. It will first identify the bottom-most non-empty level.
Then, it will delete the oldest file in that level.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10348
Test Plan:
Added a new test to verify the migration from level to FIFO where the db has multiple levels.
Extended existing test cases in db_test and db_basic_test to also verify
all entries of a key after reopening the DB with FIFO compaction.
Reviewed By: jay-zhuang
Differential Revision: D40233744
fbshipit-source-id: 6cc011d6c3467e6bfb9b6a4054b87619e69815e1
Summary:
Instead of existing calls to ps from gnu_parallel, call a new wrapper that does ps, looks for unit test like processes, and uses pstack or gdb to print thread stack traces. Also, using `ps -wwf` instead of `ps -wf` ensures output is not cut off.
For security, CircleCI runs with security restrictions on ptrace (/proc/sys/kernel/yama/ptrace_scope = 1), and this change adds a work-around to `InstallStackTraceHandler()` (only used by testing tools) to allow any process from the same user to debug it. (I've also touched >100 files to ensure all the unit tests call this function.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10828
Test Plan: local manual + temporary infinite loop in a unit test to observe in CircleCI
Reviewed By: hx235
Differential Revision: D40447634
Pulled By: pdillinger
fbshipit-source-id: 718a4c4a5b54fa0f9af2d01a446162b45e5e84e1
Summary:
Lock the penultimate level for the whole compaction inputs range, so any
key in that compaction is safe to move up from the last level to
penultimate level.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10782
Reviewed By: siying
Differential Revision: D40231540
Pulled By: siying
fbshipit-source-id: ca115cc8b4018b35d797329fa85a19b06cc8c13e
Summary:
Add option `preserve_internal_time_seconds` to preserve the internal
time information.
It's mostly for the migration of the existing data to tiered storage (
`preclude_last_level_data_seconds`). When the tiering feature is just
enabled, the existing data won't have the time information to decide if
it's hot or cold. Enabling this feature will start collect and preserve
the time information for the new data.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10747
Reviewed By: siying
Differential Revision: D39910141
Pulled By: siying
fbshipit-source-id: 25c21638e37b1a7c44006f636b7d714fe7242138
Summary:
When checking if a range [start, end) overlaps with a compaction whose range is [start1, end1), always exclude timestamp from start, end, start1 and end1, otherwise some versions of one user key may be compacted to bottommost layer while others remain in the original level.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10787
Test Plan: make check
Reviewed By: ltamasi
Differential Revision: D40187672
Pulled By: ltamasi
fbshipit-source-id: 81226267fd3e33ffa79665c62abadf2ebec45496
Summary:
To make it consistent with the compaction picker which uses the `sstableKeyCompare()` to pick the overlap files. For example, without this change, it may cut L1 files like:
```
L1: [2-21] [22-30]
L2: [1-10] [21-30]
```
Because "21" on L1 is smaller than "21" on L2. But for compaction, these 2 files are overlapped.
`sstableKeyCompare()` also take range delete into consideration which may cut file for the same key.
It also makes the `max_compaction_bytes` calculation more accurate for cases like above, the overlapped bytes was under estimated. Also make sure the 2 keys won't be splitted to 2 files because of reaching `max_compaction_bytes`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10763
Reviewed By: cbi42
Differential Revision: D39971904
Pulled By: cbi42
fbshipit-source-id: bcc309e9c3dc61a8f50667a6f633e6132c0154a8
Summary:
For RoundRobin compaction, the data should be mostly sorted per level and within level. Use normal compaction picker for RR until all expired data is compacted.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10725
Reviewed By: ajkr
Differential Revision: D39771069
Pulled By: jay-zhuang
fbshipit-source-id: 7ccf88d7c093fad5673bda73a7b08cc4757780cd
Summary:
Add user-defined timestamp support for range deletion. The new API is `DeleteRange(opt, cf, begin_key, end_key, ts)`. Most of the change is to update the comparator to compare without timestamp. Other than that, major changes are
- internal range tombstone data structures (`FragmentedRangeTombstoneList`, `RangeTombstone`, etc.) to store timestamps.
- Garbage collection of range tombstones and range tombstone covered keys during compaction.
- Get()/MultiGet() to return the timestamp of a range tombstone when needed.
- Get/Iterator with range tombstones bounded by readoptions.timestamp.
- timestamp crash test now issues DeleteRange by default.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10661
Test Plan:
- Added unit test: `make check`
- Stress test: `python3 tools/db_crashtest.py --enable_ts whitebox --readpercent=57 --prefixpercent=4 --writepercent=25 -delpercent=5 --iterpercent=5 --delrangepercent=4`
- Ran `db_bench` to measure regression when timestamp is not enabled. The tests are for write (with some range deletion) and iterate with DB fitting in memory: `./db_bench--benchmarks=fillrandom,seekrandom --writes_per_range_tombstone=200 --max_write_buffer_number=100 --min_write_buffer_number_to_merge=100 --writes=500000 --reads=500000 --seek_nexts=10 --disable_auto_compactions -disable_wal=true --max_num_range_tombstones=1000`. Did not see consistent regression in no timestamp case.
| micros/op | fillrandom | seekrandom |
| --- | --- | --- |
|main| 2.58 |10.96|
|PR 10661| 2.68 |10.63|
Reviewed By: riversand963
Differential Revision: D39441192
Pulled By: cbi42
fbshipit-source-id: f05aca3c41605caf110daf0ff405919f300ddec2
Summary:
currently, there are places in compaction_picker where we add up `compensated_file_size` of files being compacted and limit the sum to be under `max_compaction_bytes`. `compensated_file_size` contains booster for point tombstones and should be used only for determining file's compaction priority. This PR replaces `compensated_file_size` with actual file size in such places.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10728
Test Plan: CI
Reviewed By: ajkr
Differential Revision: D39789427
Pulled By: cbi42
fbshipit-source-id: 1f89fb6c0159c53bf01d8dc783f465959f442c81
Summary:
Try to align the compaction output file boundaries to the next level ones
(grandparent level), to reduce the level compaction write-amplification.
In level compaction, there are "wasted" data at the beginning and end of the
output level files. Align the file boundary can avoid such "wasted" compaction.
With this PR, it tries to align the non-bottommost level file boundaries to its
next level ones. It may cut file when the file size is large enough (at least
50% of target_file_size) and not too large (2x target_file_size).
db_bench shows about 12.56% compaction reduction:
```
TEST_TMPDIR=/data/dbbench2 ./db_bench --benchmarks=fillrandom,readrandom -max_background_jobs=12 -num=400000000 -target_file_size_base=33554432
# baseline:
Flush(GB): cumulative 25.882, interval 7.216
Cumulative compaction: 285.90 GB write, 162.36 MB/s write, 269.68 GB read, 153.15 MB/s read, 2926.7 seconds
# with this change:
Flush(GB): cumulative 25.882, interval 7.753
Cumulative compaction: 249.97 GB write, 141.96 MB/s write, 233.74 GB read, 132.74 MB/s read, 2534.9 seconds
```
The compaction simulator shows a similar result (14% with 100G random data).
As a side effect, with this PR, the SST file size can exceed the
target_file_size, but is capped at 2x target_file_size. And there will be
smaller files. Here are file size statistics when loading 100GB with the target
file size 32MB:
```
baseline this_PR
count 1.656000e+03 1.705000e+03
mean 3.116062e+07 3.028076e+07
std 7.145242e+06 8.046139e+06
```
The feature is enabled by default, to revert to the old behavior disable it
with `AdvancedColumnFamilyOptions.level_compaction_dynamic_file_size = false`
Also includes https://github.com/facebook/rocksdb/issues/1963 to cut file before skippable grandparent file. Which is for
use case like user adding 2 or more non-overlapping data range at the same
time, it can reduce the overlapping of 2 datasets in the lower levels.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10655
Reviewed By: cbi42
Differential Revision: D39552321
Pulled By: jay-zhuang
fbshipit-source-id: 640d15f159ab0cd973f2426cfc3af266fc8bdde2
Summary:
The background compaction may still running while the test end, which would cause ASAN stack-use-after-scope error.
Explicitly close the DB before test end.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10697
Test Plan:
able to reproduce with:
```
gtest-parallel ./compaction_service_test --gtest_filter=CompactionServiceTest.BasicCompactions -r 10000 -w 100
```
Reviewed By: gitbw95
Differential Revision: D39590974
Pulled By: jay-zhuang
fbshipit-source-id: da264b2e6a276afbda7d5ff7adb9d7b8d4213d90
Summary:
When user-defined timestamp is enabled, subcompaction bounds should be set up properly. When creating InputIterator for the compaction, the `start` and `end` should have their timestamp portions set to kMaxTimestamp, which is the highest possible timestamp. This is similar to what we do with setting up their sequence numbers to `kMaxSequenceNumber`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10658
Test Plan:
```bash
make check
rm -rf /dev/shm/rocksdb/* && mkdir
/dev/shm/rocksdb/rocksdb_crashtest_expected && ./db_stress
--allow_data_in_errors=True --clear_column_family_one_in=0
--continuous_verification_interval=0 --data_block_index_type=1
--db=/dev/shm/rocksdb//rocksdb_crashtest_blackbox --delpercent=5
--delrangepercent=0
--expected_values_dir=/dev/shm/rocksdb//rocksdb_crashtest_expected
--iterpercent=0 --max_background_compactions=20
--max_bytes_for_level_base=10485760 --max_key=25000000
--max_write_batch_group_size_bytes=1048576 --nooverwritepercent=1
--ops_per_thread=300000 --paranoid_file_checks=1 --partition_filters=0
--prefix_size=8 --prefixpercent=5 --readpercent=30 --reopen=0
--snapshot_hold_ops=100000 --subcompactions=4
--target_file_size_base=65536 --target_file_size_multiplier=2
--test_batches_snapshots=0 --test_cf_consistency=0 --use_multiget=1
--user_timestamp_size=8 --value_size_mult=32 --verify_checksum=1
--write_buffer_size=65536 --writepercent=60 -disable_wal=1
-column_families=1
```
Reviewed By: akankshamahajan15
Differential Revision: D39393402
Pulled By: riversand963
fbshipit-source-id: f276e35b19fce51a175c368a502fb0718d1f3871
Summary:
Although we've been tracking SST unique IDs in the DB manifest
unconditionally, checking has been opt-in and with an extra pass at DB::Open
time. This changes the behavior of `verify_sst_unique_id_in_manifest` to
check unique ID against manifest every time an SST file is opened through
table cache (normal DB operations), replacing the explicit pass over files
at DB::Open time. This change also enables the option by default and
removes the "EXPERIMENTAL" designation.
One possible criticism is that the option no longer ensures the integrity
of a DB at Open time. This is far from an all-or-nothing issue. Verifying
the IDs of all SST files hardly ensures all the data in the DB is readable.
(VerifyChecksum is supposed to do that.) Also, with
max_open_files=-1 (default, extremely common), all SST files are
opened at DB::Open time anyway.
Implementation details:
* `VerifySstUniqueIdInManifest()` functions are the extra/explicit pass
that is now removed.
* Unit tests that manipulate/corrupt table properties have to opt out of
this check, because that corrupts the "actual" unique id. (And even for
testing we don't currently have a mechanism to set "no unique id"
in the in-memory file metadata for new files.)
* A lot of other unit test churn relates to (a) default checking on, and
(b) checking on SST open even without DB::Open (e.g. on flush)
* Use `FileMetaData` for more `TableCache` operations (in place of
`FileDescriptor`) so that we have access to the unique_id whenever
we might need to open an SST file. **There is the possibility of
performance impact because we can no longer use the more
localized `fd` part of an `FdWithKeyRange` but instead follow the
`file_metadata` pointer. However, this change (possible regression)
is only done for `GetMemoryUsageByTableReaders`.**
* Removed a completely unnecessary constructor overload of
`TableReaderOptions`
Possible follow-up:
* Verification only happens when opening through table cache. Are there
more places where this should happen?
* Improve error message when there is a file size mismatch vs. manifest
(FIXME added in the appropriate place).
* I'm not sure there's a justification for `FileDescriptor` to be distinct from
`FileMetaData`.
* I'm skeptical that `FdWithKeyRange` really still makes sense for
optimizing some data locality by duplicating some data in memory, but I
could be wrong.
* An unnecessary overload of NewTableReader was recently added, in
the public API nonetheless (though unusable there). It should be cleaned
up to put most things under `TableReaderOptions`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10532
Test Plan:
updated unit tests
Performance test showing no significant difference (just noise I think):
`./db_bench -benchmarks=readwhilewriting[-X10] -num=3000000 -disable_wal=1 -bloom_bits=8 -write_buffer_size=1000000 -target_file_size_base=1000000`
Before: readwhilewriting [AVG 10 runs] : 68702 (± 6932) ops/sec
After: readwhilewriting [AVG 10 runs] : 68239 (± 7198) ops/sec
Reviewed By: jay-zhuang
Differential Revision: D38765551
Pulled By: pdillinger
fbshipit-source-id: a827a708155f12344ab2a5c16e7701c7636da4c2
Summary:
**Context:**
Below crash test revealed a bug that directory containing CURRENT file (short for `dir_contains_current_file` below) was not always get synced after a new CURRENT is created and being called with `RenameFile` as part of the creation.
This bug exposes a risk that such un-synced directory containing the updated CURRENT can’t survive a host crash (e.g, power loss) hence get corrupted. This then will be followed by a recovery from a corrupted CURRENT that we don't want.
The root-cause is that a nullptr `FSDirectory* dir_contains_current_file` sometimes gets passed-down to `SetCurrentFile()` hence in those case `dir_contains_current_file->FSDirectory::FsyncWithDirOptions()` will be skipped (which otherwise will internally call`Env/FS::SyncDic()` )
```
./db_stress --acquire_snapshot_one_in=10000 --adaptive_readahead=1 --allow_data_in_errors=True --avoid_unnecessary_blocking_io=0 --backup_max_size=104857600 --backup_one_in=100000 --batch_protection_bytes_per_key=8 --block_size=16384 --bloom_bits=134.8015470676662 --bottommost_compression_type=disable --cache_size=8388608 --checkpoint_one_in=1000000 --checksum_type=kCRC32c --clear_column_family_one_in=0 --compact_files_one_in=1000000 --compact_range_one_in=1000000 --compaction_pri=2 --compaction_ttl=100 --compression_max_dict_buffer_bytes=511 --compression_max_dict_bytes=16384 --compression_type=zstd --compression_use_zstd_dict_trainer=1 --compression_zstd_max_train_bytes=65536 --continuous_verification_interval=0 --data_block_index_type=0 --db=$db --db_write_buffer_size=1048576 --delpercent=5 --delrangepercent=0 --destroy_db_initially=0 --disable_wal=0 --enable_compaction_filter=0 --enable_pipelined_write=1 --expected_values_dir=$exp --fail_if_options_file_error=1 --file_checksum_impl=none --flush_one_in=1000000 --get_current_wal_file_one_in=0 --get_live_files_one_in=1000000 --get_property_one_in=1000000 --get_sorted_wal_files_one_in=0 --index_block_restart_interval=4 --ingest_external_file_one_in=0 --iterpercent=10 --key_len_percent_dist=1,30,69 --level_compaction_dynamic_level_bytes=True --mark_for_compaction_one_file_in=10 --max_background_compactions=20 --max_bytes_for_level_base=10485760 --max_key=10000 --max_key_len=3 --max_manifest_file_size=16384 --max_write_batch_group_size_bytes=64 --max_write_buffer_number=3 --max_write_buffer_size_to_maintain=0 --memtable_prefix_bloom_size_ratio=0.001 --memtable_protection_bytes_per_key=1 --memtable_whole_key_filtering=1 --mmap_read=1 --nooverwritepercent=1 --open_metadata_write_fault_one_in=0 --open_read_fault_one_in=0 --open_write_fault_one_in=0 --ops_per_thread=100000000 --optimize_filters_for_memory=1 --paranoid_file_checks=1 --partition_pinning=2 --pause_background_one_in=1000000 --periodic_compaction_seconds=0 --prefix_size=5 --prefixpercent=5 --prepopulate_block_cache=1 --progress_reports=0 --read_fault_one_in=1000 --readpercent=45 --recycle_log_file_num=0 --reopen=0 --ribbon_starting_level=999 --secondary_cache_fault_one_in=32 --secondary_cache_uri=compressed_secondary_cache://capacity=8388608 --set_options_one_in=10000 --snapshot_hold_ops=100000 --sst_file_manager_bytes_per_sec=0 --sst_file_manager_bytes_per_truncate=0 --subcompactions=3 --sync_fault_injection=1 --target_file_size_base=2097 --target_file_size_multiplier=2 --test_batches_snapshots=1 --top_level_index_pinning=1 --use_full_merge_v1=1 --use_merge=1 --value_size_mult=32 --verify_checksum=1 --verify_checksum_one_in=1000000 --verify_db_one_in=100000 --verify_sst_unique_id_in_manifest=1 --wal_bytes_per_sync=524288 --write_buffer_size=4194 --writepercent=35
```
```
stderr:
WARNING: prefix_size is non-zero but memtablerep != prefix_hash
db_stress: utilities/fault_injection_fs.cc:748: virtual rocksdb::IOStatus rocksdb::FaultInjectionTestFS::RenameFile(const std::string &, const std::string &, const rocksdb::IOOptions &, rocksdb::IODebugContext *): Assertion `tlist.find(tdn.second) == tlist.end()' failed.`
```
**Summary:**
The PR ensured the non-test path pass down a non-null dir containing CURRENT (which is by current RocksDB assumption just db_dir) by doing the following:
- Renamed `directory_to_fsync` as `dir_contains_current_file` in `SetCurrentFile()` to tighten the association between this directory and CURRENT file
- Changed `SetCurrentFile()` API to require `dir_contains_current_file` being passed-in, instead of making it by default nullptr.
- Because `SetCurrentFile()`'s `dir_contains_current_file` is passed down from `VersionSet::LogAndApply()` then `VersionSet::ProcessManifestWrites()` (i.e, think about this as a chain of 3 functions related to MANIFEST update), these 2 functions also got refactored to require `dir_contains_current_file`
- Updated the non-test-path callers of these 3 functions to obtain and pass in non-nullptr `dir_contains_current_file`, which by current assumption of RocksDB, is the `FSDirectory* db_dir`.
- `db_impl` path will obtain `DBImpl::directories_.getDbDir()` while others with no access to such `directories_` are obtained on the fly by creating such object `FileSystem::NewDirectory(..)` and manage it by unique pointers to ensure short life time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10573
Test Plan:
- `make check`
- Passed the repro db_stress command
- For future improvement, since we currently don't assert dir containing CURRENT to be non-nullptr due to https://github.com/facebook/rocksdb/pull/10573#pullrequestreview-1087698899, there is still chances that future developers mistakenly pass down nullptr dir containing CURRENT thus resulting skipped sync dir and cause the bug again. Therefore a smarter test (e.g, such as quoted from ajkr "(make) unsynced data loss to be dropping files corresponding to unsynced directory entries") is still needed.
Reviewed By: ajkr
Differential Revision: D39005886
Pulled By: hx235
fbshipit-source-id: 336fb9090d0cfa6ca3dd580db86268007dde7f5a
Summary:
In UniversalCompactionBuilder::PickCompactionToReduceSortedRuns, we passed start_level to get compression type and options. I think that is wrong and we should use output_level instead.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10515
Reviewed By: hx235
Differential Revision: D38611335
Pulled By: ajkr
fbshipit-source-id: bb860caed4b6c6bbde8f75fc50cf875a9f04723d
Summary:
The info LOG file does not currently give any direct
information about the existence of old, live snapshots, nor how to
estimate wall time from a sequence number within the scope of LOG
history. This change addresses both with:
* Logging smallest and largest seqnos for generated SST files, which can
help associate sequence numbers with write time (based on flushes).
* Logging oldest_snapshot_seqno for each compaction, which (along with
that seqno info) helps us to determine how much old data might be kept
around for old (leaked?) snapshots. Including the date here I thought might
be excessive.
I wanted to log the date and seqno of the oldest snapshot with periodic
stats, but the current structure of the code doesn't really support that
because `DumpDBStats` doesn't have access to the DB object.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10454
Test Plan:
manual inspect LOG from
`KEEP_DB=1 ./db_basic_test --gtest_filter=*CompactBetweenSnapshots*`
Reviewed By: ajkr
Differential Revision: D38326948
Pulled By: pdillinger
fbshipit-source-id: 294918ffc04a419844146cd826045321b4d5c038
Summary:
New blobdb has a bug in compaction filter, where `blob_value_` is not reset for next iterated key. This will cause blob_value_ not empty and previous value read from blob is passed into the filter function for next key, even if its value is not in blob. Fixed by reseting regardless of key type.
Test Case:
Add `FilterByValueLength` test case in `DBBlobCompactionTest`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10391
Reviewed By: riversand963
Differential Revision: D38629900
Pulled By: ltamasi
fbshipit-source-id: 47d23ff2e5ec697958a210db9e6ceeb8b2fc49fa
Summary:
The main purpose is to make debugging easier without sacrificing performance.
Instead of using a boolean variable for `CompactionIterator::valid_`, we can extend it to an `uint8_t`,
using the LSB to denote if the compaction iterator is valid and 4 additional bits to denote where
the iterator is set valid inside `NextFromInput()`. Therefore, when the control flow reaches
`PrepareOutput()` and hits assertion there, we can have a better idea of what has gone wrong.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10505
Test Plan:
make check
```
TEST_TMPDIR=/dev/shm/rocksdb time ./db_bench -compression_type=none -write_buffer_size=1073741824 -benchmarks=fillseq,flush
```
The above command has a 'flush' benchmark which uses `CompactionIterator`. I haven't observed any CPU regression or drop in throughput or latency increase.
Reviewed By: ltamasi
Differential Revision: D38551615
Pulled By: riversand963
fbshipit-source-id: 1250848fc118bb753d71fa9ff8ba840df999f5e0
Summary:
Change tiered compaction feature from `bottommost_temperture` to
`last_level_temperture`. The old option is kept for migration purpose only,
which is behaving the same as `last_level_temperture` and it will be removed in
the next release.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10471
Test Plan: CI
Reviewed By: siying
Differential Revision: D38450621
Pulled By: jay-zhuang
fbshipit-source-id: cc1cdf8bad409376fec0152abc0a64fb72a91527
Summary:
Current universal compaction picker may cause extra size amplification
compaction if there're more hot data on penultimate level. Improve the picker
to skip the last level for size amp calculation if tiered compaction is
enabled, which can
1. avoid extra unnecessary size amp compaction;
2. typically cold tier (the last level) is not size constrained, so skip size
amp for cold tier is intended;
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10467
Test Plan: CI and added unittest
Reviewed By: siying
Differential Revision: D38391350
Pulled By: jay-zhuang
fbshipit-source-id: 103c0731c05e0a7e8f267e9e829d022328be25d2
Summary:
During compaction, blobs are currently read using the default
`ReadOptions`, which has the `fill_cache` flag set to true. Earlier,
this didn't make any difference since we didn't have a blob cache;
however, now we have to explicitly set this flag to false to avoid
polluting the cache during compaction.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10457
Test Plan: `make check`
Reviewed By: riversand963
Differential Revision: D38333528
Pulled By: ltamasi
fbshipit-source-id: 5b4d49a1e39543bee73c7df2aa9194fb101875e2
Summary:
FileMetaData::[min|max]_timestamp are not currently being used or
tracked by RocksDB, even when user-defined timestamp is enabled. Each of
them is a std::string which can occupy 32 bytes. Remove them for now.
They may be added back when we have a pressing need for them. When we do
add them back, consider store them in a more compact way, e.g. one
boolean flag and a byte array of size 16.
Per file min/max timestamp bounds are available as table properties.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10443
Test Plan: make check
Reviewed By: pdillinger
Differential Revision: D38292275
Pulled By: riversand963
fbshipit-source-id: 841dc4e855ad8f8481c80cb020603de9607c9c94
Summary:
The subcompaction logic currently picks file boundaries as subcompaction boundaries. This is not compatible with user-defined timestamps because of two issues.
Issue1: ReadOptions.iterate_lower_bound and ReadOptions.iterate_upper_bound contains timestamps which results in assertion failure as BlockBasedTableIterator expects bounds to be without timestamps. As result, because of wrong comparison end key is returned as user_key resulting in assertion failure.
Issue2: Since it might result in two keys that only differ by user timestamp getting processed by two different subcompactions (and thus two different CompactionIterator state machines), which in turn can cause data correction issues.
This PR provide support to reenable subcompactions with user-defined timestamps.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10344
Test Plan:
Added new unit test
- Without fix for Issue1 unit test MultipleSubCompactions fails with error:
```
db_with_timestamp_compaction_test: ./db/compaction/clipping_iterator.h:247: void rocksdb::ClippingIterat│
or::AssertBounds(): Assertion `!valid_ || !end_ || cmp_->Compare(key(), *end_) < 0' failed.
Received signal 6 (Aborted) │
#0 /usr/local/fbcode/platform009/lib/libc.so.6(gsignal+0x100) [0x7f8fbbbfe530] db_with_timestamp_compaction_test: ./db/compaction/clipping_iterator.h:247: void rocksdb::ClippingIterator::AssertBounds(): Assertion `!valid_ || !end_ || cmp_->Compare(key(), *end_) < 0' failed.
Aborted (core dumped)
```
Ran stress test
`make crash_test_with_ts -j32`
Reviewed By: riversand963
Differential Revision: D38220841
Pulled By: akankshamahajan15
fbshipit-source-id: 5d5cae2bd37fcaeba1e77fce0a69070ad4158ccb
Summary:
Allow sufficient subcompactions can be used when the number of input files is less than `max_subcompactions` under round-robin compaction priority.
Test Case:
Add `RoundRobinWithoutAdditionalResources` into `db_compaction_test`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10422
Reviewed By: ajkr
Differential Revision: D38186545
Pulled By: littlepig2013
fbshipit-source-id: b8e5098306f1e5b9561dfafafc8300a38f7fe88e
Summary:
Earlier implementation of round-robin priority can only pick one file at a time and disallows parallel compactions within the same level. In this PR, round-robin compaction policy will expand towards more input files with respecting some additional constraints, which are summarized as follows:
* Constraint 1: We can only pick consecutive files
- Constraint 1a: When a file is being compacted (or some input files are being compacted after expanding), we cannot choose it and have to stop choosing more files
- Constraint 1b: When we reach the last file (with the largest keys), we cannot choose more files (the next file will be the first one with small keys)
* Constraint 2: We should ensure the total compaction bytes (including the overlapped files from the next level) is no more than `mutable_cf_options_.max_compaction_bytes`
* Constraint 3: We try our best to pick as many files as possible so that the post-compaction level size can be just less than `MaxBytesForLevel(start_level_)`
* Constraint 4: If trivial move is allowed, we reuse the logic of `TryNonL0TrivialMove()` instead of expanding files with Constraint 3
More details can be found in `LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion()`.
The above optimization accelerates the process of moving the compaction cursor, in which the write-amp can be further reduced. While a large compaction may lead to high write stall, we break this large compaction into several subcompactions **regardless of** the `max_subcompactions` limit. The number of subcompactions for round-robin compaction priority is determined through the following steps:
* Step 1: Initialized against `max_output_file_limit`, the number of input files in the start level, and also the range size limit `ranges.size()`
* Step 2: Call `AcquireSubcompactionResources()`when max subcompactions is not sufficient, but we may or may not obtain desired resources, additional number of resources is stored in `extra_num_subcompaction_threads_reserved_`). Subcompaction limit is changed and update `num_planned_subcompactions` with `GetSubcompactionLimit()`
* Step 3: Call `ShrinkSubcompactionResources()` to ensure extra resources can be released (extra resources may exist for round-robin compaction when the number of actual number of subcompactions is less than the number of planned subcompactions)
More details can be found in `CompactionJob::AcquireSubcompactionResources()`,`CompactionJob::ShrinkSubcompactionResources()`, and `CompactionJob::ReleaseSubcompactionResources()`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10341
Test Plan: Add `CompactionPriMultipleFilesRoundRobin[1-3]` unit test in `compaction_picker_test.cc` and `RoundRobinSubcompactionsAgainstResources.SubcompactionsUsingResources/[0-4]`, `RoundRobinSubcompactionsAgainstPressureToken.PressureTokenTest/[0-1]` in `db_compaction_test.cc`
Reviewed By: ajkr, hx235
Differential Revision: D37792644
Pulled By: littlepig2013
fbshipit-source-id: 7fecb7c4ffd97b34bbf6e3b760b2c35a772a0657
Summary:
Unit tests still haven't been fixed. Also need to add more tests. But I ran some simple fillrandom db_bench and the partitioning feels reasonable.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10393
Test Plan:
1. Make sure existing tests pass. This should cover some basic sub compaction logic to be correct and the partitioning result is reasonable;
2. Add a new unit test to ApproximateKeyAnchors()
3. Run some db_bench with max_subcompaction = 4 and watch the compaction is indeed partitioned evenly.
Reviewed By: jay-zhuang
Differential Revision: D38043783
fbshipit-source-id: 085008e0f85f9b7c5abff7800307618320efb19f
Summary:
Many workloads have temporal locality, where recently written items are read back in a short period of time. When using remote file systems, this is inefficient since it involves network traffic and higher latencies. Because of this, we would like to support prepopulating the blob cache during flush.
This task is a part of https://github.com/facebook/rocksdb/issues/10156
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10298
Reviewed By: ltamasi
Differential Revision: D37908743
Pulled By: gangliao
fbshipit-source-id: 9feaed234bc719d38f0c02975c1ad19fa4bb37d1
Summary:
Using the Sequence number to time mapping to decide if a key is hot or not in
compaction and place it in the corresponding level.
Note: the feature is not complete, level compaction will run indefinitely until
all penultimate level data is cold and small enough to not trigger compaction.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10370
Test Plan:
CI
* Run basic db_bench for universal compaction manually
Reviewed By: siying
Differential Revision: D37892338
Pulled By: jay-zhuang
fbshipit-source-id: 792bbd91b1ccc2f62b5d14c53118434bcaac4bbe
Summary:
Which will be used for tiered storage to preclude hot data from
compacting to the cold tier (the last level).
Internally, adding seqno to time mapping. A periodic_task is scheduled
to record the current_seqno -> current_time in certain cadence. When
memtable flush, the mapping informaiton is stored in sstable property.
During compaction, the mapping information are merged and get the
approximate time of sequence number, which is used to determine if a key
is recently inserted or not and preclude it from the last level if it's
recently inserted (within the `preclude_last_level_data_seconds`).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10338
Test Plan: CI
Reviewed By: siying
Differential Revision: D37810187
Pulled By: jay-zhuang
fbshipit-source-id: 6953be7a18a99de8b1cb3b162d712f79c2b4899f
Summary:
InternalKeyComparator is an internal class which is a simple wrapper of Comparator. https://github.com/facebook/rocksdb/pull/8336 made Comparator customizeable. As a side effect, internal key comparator was made configurable too. This introduces overhead to this simple wrapper. For example, every InternalKeyComparator will have an std::vector attached to it, which consumes memory and possible allocation overhead too.
We remove InternalKeyComparator from being customizable by making InternalKeyComparator not a subclass of Comparator.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10342
Test Plan: Run existing CI tests and make sure it doesn't fail
Reviewed By: riversand963
Differential Revision: D37771351
fbshipit-source-id: 917256ee04b2796ed82974549c734fb6c4d8ccee
Summary:
Support per_key_placement for last level compaction, which will
be used for tiered compaction.
* compaction iterator reports which level a key should output to;
* compaction get the output level information and check if it's safe to
output the data to penultimate level;
* all compaction output files will be installed.
* extra internal compaction stats added for penultimate level.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9964
Test Plan:
* Unittest
* db_bench, no significate difference: https://gist.github.com/jay-zhuang/3645f8fb97ec0ab47c10704bb39fd6e4
* microbench manual compaction no significate difference: https://gist.github.com/jay-zhuang/ba679b3e89e24992615ee9eef310e6dd
* run the db_stress multiple times (not covering the new feature) looks good (internal: https://fburl.com/sandcastle/9w84pp2m)
Reviewed By: ajkr
Differential Revision: D36249494
Pulled By: jay-zhuang
fbshipit-source-id: a96da57c8031c1df83e4a7a8567b657a112b80a3
Summary:
InternalKeyComparator is a thin wrapper around user comparator. Storing a string for name is relatively expensive to this small wrapper for both CPU and memory usage. Try to remove it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10343
Test Plan: Run existing tests
Reviewed By: ajkr
Differential Revision: D37772469
fbshipit-source-id: d2d106a8d022193058fd7f6b220108e3d94aca34
Summary:
Earlier implementation of cutting the output files with a compact cursor under Round-Robin priority uses `Valid()` to determine if the `output_split_key` is valid in `ShouldStopBefore`. This contributes to excessive CPU computation, as pointed out by [this issue](https://github.com/facebook/rocksdb/issues/10315). In this PR, we change the type of `output_split_key` to be `InternalKey*` and set it as `nullptr` if it is not going to be used in `ShouldStopBefore`, `Valid()` condition checking can be avoided using that pointer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10316
Reviewed By: ajkr
Differential Revision: D37661492
Pulled By: littlepig2013
fbshipit-source-id: 66ff1105f3378e5573d3a126fdaff9bb23b5498f
Summary:
In leveled compaction, try to trivial move more than one files if possible, up to 4 files or max_compaction_bytes. This is to allow higher write throughput for some use cases where data is loaded in sequential order, where appying compaction results is the bottleneck.
When pick up a file to compact and it doesn't have overlapping files in the next level, try to expand to the next file if there is still no overlapping.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10190
Test Plan:
Add some unit tests.
For performance, Try to run
./db_bench_multi_move --benchmarks=fillseq --compression_type=lz4 --write_buffer_size=5000000 --num=100000000 --value_size=1000 -level_compaction_dynamic_level_bytes
Together with https://github.com/facebook/rocksdb/pull/10188 , stalling will be eliminated in this benchmark.
Reviewed By: jay-zhuang
Differential Revision: D37230647
fbshipit-source-id: 42b260f545c46abc5d90335ac2bbfcd09602b549
Summary:
In leveled compaction, L0->L1 trivial move will allow more than one file to be moved in one compaction. This would allow L0 files to be moved down faster when data is loaded in sequential order, making slowdown or stop condition harder to hit. Also seek L0->L1 trivial move when only some files qualify.
1. We always try to find L0->L1 trivial move from the oldest files. Keep including newer files, until adding a new file won't trigger a trivial move
2. Modify the trivial move condition so that this compaction would be tagged as trivial move.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10188
Test Plan:
See throughput improvements with db_bench with fast fillseq benchmark and small L0 files:
./db_bench_l0_move --benchmarks=fillseq --compression_type=lz4 --write_buffer_size=5000000 --num=100000000 --value_size=1000 -level_compaction_dynamic_level_bytes
The throughput improved by about 50%. Stalling still happens though.
Reviewed By: jay-zhuang
Differential Revision: D37224743
fbshipit-source-id: 8958d97f22e12bdfc14d2e85930f6fa0070e9659
Summary:
In round-robin compaction priority, when splitting the compaction into sub-compactions, the earlier implementation takes into account the compact cursor to have full use of available sub-compactions. But this may result in unbalanced sub-compactions, so we remove this here. The removal does not affect the cursor-based splitting mechanism within a sub-compaction, and thus the output files are still ensured to be split according to the cursor.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10289
Reviewed By: ajkr
Differential Revision: D37559091
Pulled By: littlepig2013
fbshipit-source-id: b8b45b99f63b09cf873f7f049bcb4ab13871fffc
Summary:
The patch builds on https://github.com/facebook/rocksdb/pull/9915 and adds
a new API called `PutEntity` that can be used to write a wide-column entity
to the database. The new API is added to both `DB` and `WriteBatch`. Note
that currently there is no way to retrieve these entities; more precisely, all
read APIs (`Get`, `MultiGet`, and iterator) return `NotSupported` when they
encounter a wide-column entity that is required to answer a query. Read-side
support (as well as other missing functionality like `Merge`, compaction filter,
and timestamp support) will be added in later PRs.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10242
Test Plan: `make check`
Reviewed By: riversand963
Differential Revision: D37369748
Pulled By: ltamasi
fbshipit-source-id: 7f5e412359ed7a400fd80b897dae5599dbcd685d
