Summary:
This is essentially resurrection and fixing of the part of
https://github.com/facebook/rocksdb/issues/8198 that was reverted in https://github.com/facebook/rocksdb/issues/8212, using data added in https://github.com/facebook/rocksdb/issues/8246. Basically,
when configuring Ribbon filter, you can specify an LSM level before which
Bloom will be used instead of Ribbon. But Bloom is only considered for
Leveled and Universal compaction styles and file going into a known LSM
level. This way, SST file writer, FIFO compaction, etc. use Ribbon filter as
you would expect with NewRibbonFilterPolicy.
So that this can be controlled with a single int value and so that flushes
can be distinguished from intra-L0, we consider flush to go to level -1 for
the purposes of this option. (Explained in API comment.)
I also expect the most common and recommended Ribbon configuration to
use Bloom during flush, to minimize slowing down writes and because according
to my estimates, Ribbon only pays off if the structure lives in memory for
more than an hour. Thus, I have changed the default for NewRibbonFilterPolicy
to be this mild hybrid configuration. I don't really want to add something like
NewHybridFilterPolicy because at least the mild hybrid configuration (Bloom for
flush, Ribbon otherwise) should be considered a natural choice.
C APIs also updated, but because they don't support overloading,
rocksdb_filterpolicy_create_ribbon is kept pure ribbon for clarity and
rocksdb_filterpolicy_create_ribbon_hybrid must be called for a hybrid
configuration. While touching C API, I changed bits per key options from
int to double.
BuiltinFilterPolicy is needed so that LevelThresholdFilterPolicy doesn't inherit
unused fields from BloomFilterPolicy.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8679
Test Plan: new + updated tests, including crash test
Reviewed By: jay-zhuang
Differential Revision: D30445797
Pulled By: pdillinger
fbshipit-source-id: 6f5aeddfd6d79f7e55493b563c2d1d2d568892e1
Summary:
Pass BlobFileCompletionCallback in case of atomic flush and
compaction job which is currently nullptr(default parameter).
BlobFileCompletionCallback is used in case of IntegratedBlobDB to report new blob files to
SstFileManager.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8681
Test Plan: CircleCI jobs
Reviewed By: ltamasi
Differential Revision: D30445998
Pulled By: akankshamahajan15
fbshipit-source-id: ba48093843864faec57f1f365cce7b5a569c4021
Summary:
- Fix issue with OptionType::Vector when the nested item is a Customizable with no names
- Fix issue with OptionType::Vector to appropriately wrap the elements in a Vector;
- Fix an issue with nested Customizable object with a null immutable object still appearing in the mutable options;
- Fix/Add tests for null/empty customizable objects
- Move the RegisterTestObjects from customizable_test into testutil.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8566
Reviewed By: zhichao-cao
Differential Revision: D30303724
Pulled By: mrambacher
fbshipit-source-id: 33fa8ea2a3b663210cb356da05e64aab7585b1b5
Summary:
`Replayer::Execute()` can directly returns the result (e.g, request latency, DB::Get() return code, returned value, etc.)
`Replayer::Replay()` reports the results via a callback function.
New interface:
`TraceRecordResult` in "rocksdb/trace_record_result.h".
`DBTest2.TraceAndReplay` and `DBTest2.TraceAndManualReplay` are updated accordingly.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8657
Reviewed By: ajkr
Differential Revision: D30290216
Pulled By: autopear
fbshipit-source-id: 3c8d4e6b180ec743de1a9d9dcaee86064c74f0d6
Summary:
In debug mode, we are seeing assertion failure as follows
```
db/compaction/compaction_iterator.cc:980: void rocksdb::CompactionIterator::PrepareOutput(): \
Assertion `ikey_.type != kTypeDeletion && ikey_.type != kTypeSingleDeletion' failed.
```
It is caused by releasing earliest snapshot during compaction between the execution of
`NextFromInput()` and `PrepareOutput()`.
In one case, as demonstrated in unit test `WritePreparedTransaction.ReleaseEarliestSnapshotDuringCompaction_WithSD2`,
incorrect result may be returned by a following range scan if we disable assertion, as in opt compilation
level: the SingleDelete marker's sequence number is zeroed out, but the preceding PUT is also
outputted to the SST file after compaction. Due to the logic of DBIter, the PUT will not be
skipped and will be returned by iterator in range scan. https://github.com/facebook/rocksdb/issues/8661 illustrates what happened.
Fix by taking a more conservative approach: make compaction zero out sequence number only
if key is in the earliest snapshot when the compaction starts.
Another assertion failure is
```
Assertion `current_user_key_snapshot_ == last_snapshot' failed.
```
It's caused by releasing the snapshot between the PUT and SingleDelete during compaction.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8608
Test Plan: make check
Reviewed By: jay-zhuang
Differential Revision: D30145645
Pulled By: riversand963
fbshipit-source-id: 699f58e66faf70732ad53810ccef43935d3bbe81
Summary:
The patch adds statistics support to the integrated BlobDB implementation,
namely the tickers `BLOB_DB_BLOB_FILE_BYTES_READ` and
`BLOB_DB_GC_{NUM_KEYS,BYTES}_RELOCATED`, and the histograms
`BLOB_DB_(DE)COMPRESSION_MICROS`. (Some other statistics, like
`BLOB_DB_BLOB_FILE_BYTES_WRITTEN`, `BLOB_DB_BLOB_FILE_SYNCED`,
`BLOB_DB_BLOB_FILE_{READ,WRITE,SYNC}_MICROS` were already supported.)
Note that the vast majority of the old BlobDB's tickers/histograms are not
really applicable to the new implementation, since they e.g. pertain to calling
dedicated BlobDB APIs (which the integrated BlobDB does not have) or are
tied to the legacy BlobDB's design of writing blob files synchronously when
a write API is called. Such statistics are marked "legacy BlobDB only" in
`statistics.h`.
Fixes https://github.com/facebook/rocksdb/issues/8645 .
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8667
Test Plan: Ran `make check` and tested the new statistics using `db_bench`.
Reviewed By: riversand963
Differential Revision: D30356884
Pulled By: ltamasi
fbshipit-source-id: 5f8a833faee60401c5643c2f0a6c0415488190a4
Summary:
Add a stat for secondary cache hits. The ```Cache::Lookup``` API had an unused ```stats``` parameter. This PR uses that to pass the pointer to a ```Statistics``` object that ```LRUCache``` uses to record the stat.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8666
Test Plan: Update a unit test in lru_cache_test
Reviewed By: zhichao-cao
Differential Revision: D30353816
Pulled By: anand1976
fbshipit-source-id: 2046f78b460428877a26ffdd2bb914ae47dfbe77
Summary:
- Remove extra `;` in trace_record.h
- Remove some unnecessary `assert` in trace_record_handler.cc
- Initialize `env_` after` exec_handler_` in `ReplayerImpl` to let db be asserted in creating the handler before getting `db->GetEnv()`.
- Update history to include the new `TraceReader::Reset()`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8652
Reviewed By: ajkr
Differential Revision: D30276872
Pulled By: autopear
fbshipit-source-id: 476ee162e0f241490c6209307448343a5b326b37
Summary:
New public interfaces:
`TraceRecord` and `TraceRecord::Handler`, available in "rocksdb/trace_record.h".
`Replayer`, available in `rocksdb/utilities/replayer.h`.
User can use `DB::NewDefaultReplayer()` to create a Replayer to auto/manual replay a trace file.
Unit tests:
- `./db_test2 --gtest_filter="DBTest2.TraceAndReplay"`: Updated with the internal API changes.
- `./db_test2 --gtest_filter="DBTest2.TraceAndManualReplay"`: New for manual replay.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8611
Reviewed By: ajkr
Differential Revision: D30266329
Pulled By: autopear
fbshipit-source-id: 1ecb3cbbedae0f6a67c18f0cc82e002b4d81b6f8
Summary:
Add comment for `options.allow_fallocate` that btrfs
preallocated space are not freed and a suggestion to disable
preallocation.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8646
Test Plan: No code change
Reviewed By: ajkr
Differential Revision: D30240050
Pulled By: jay-zhuang
fbshipit-source-id: 75b7190bc8276ce8d8ac2d0cb9064b386cbf4768
Summary:
Some FIFO users want to keep the data for longer, but the old data is rarely accessed. This feature allows users to configure FIFO compaction so that data older than a threshold is moved to a warm storage tier.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8310
Test Plan: Add several unit tests.
Reviewed By: ajkr
Differential Revision: D28493792
fbshipit-source-id: c14824ea634814dee5278b449ab5c98b6e0b5501
Summary:
`CompareKeyContext::operator()` on the trunk has a bug: when comparing
column family IDs, `lhs` is used for both sides of the comparison. This
results in the `KeyContext`s getting sorted solely based on key, which
in turn means that keys with the same column family do not necessarily
form a single range in the sorted list. This violates an assumption of the
batched `MultiGet` logic, leading to the same column family
showing up multiple times in the list of `MultiGetColumnFamilyData`.
The end result is the code attempting to check out the thread-local
`SuperVersion` for the same CF multiple times, causing an
assertion violation in debug builds and memory corruption/crash in
release builds.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8633
Test Plan: `make check`
Reviewed By: riversand963
Differential Revision: D30169182
Pulled By: ltamasi
fbshipit-source-id: a47710652df7e95b14b40fb710924c11a8478023
Summary:
Guarantees that if a restore is interrupted, DB::Open will fail. This works by
restoring CURRENT first to CURRENT.tmp then as a final step renaming to CURRENT.
Also makes restore respect BackupEngineOptions::sync (default true). When set,
the restore is guaranteed persisted by the time it returns OK. Also makes the above
atomicity guarantee work in case the interruption is power loss or OS crash (not just
process interruption or crash).
Fixes https://github.com/facebook/rocksdb/issues/8500
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8568
Test Plan:
added to backup mini-stress unit test. Passes with
gtest_repeat=100 (whereas fails 7 times without the CURRENT.tmp)
Reviewed By: akankshamahajan15
Differential Revision: D29812605
Pulled By: pdillinger
fbshipit-source-id: 24e9a993b305b1835ca95558fa7a7152e54cda8e
Summary:
Previously we attempted to rename "LOG" to "LOG.old.*" without checking
its existence first. "LOG" had no reason to exist in a new DB.
Errors in renaming a non-existent "LOG" were swallowed via
`PermitUncheckedError()` so things worked. However the storage service's
error monitoring was detecting all these benign rename failures. So it
is better to fix it. Also with this PR we can now distinguish rename failure
for other reasons and return them.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8622
Test Plan: new unit test
Reviewed By: akankshamahajan15
Differential Revision: D30115189
Pulled By: ajkr
fbshipit-source-id: e2f337ffb2bd171be0203172abc8e16e7809b170
Summary:
Insert warm blocks (data, uncompressed dict, index and filter blocks) during flush in Block cache which is enabled under option BlockBasedTableOptions.prepopulate_block_cache.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8561
Test Plan: Added unit test
Reviewed By: anand1976
Differential Revision: D29773411
Pulled By: akankshamahajan15
fbshipit-source-id: 6631123c10134340ef0bd7e90baafaa6deba0e66
Summary:
An arbitrary string can be used as a delimiter in StringAppend merge operator
flavor. In particular, it allows using an empty string, combining binary values for
the same key byte-to-byte one next to another.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8536
Reviewed By: mrambacher
Differential Revision: D29962120
Pulled By: zhichao-cao
fbshipit-source-id: 4ef5d846a47835cf428a11200409e30e2dbffc4f
Summary:
Prior to this change, the "wal_dir" DBOption would always be set (defaults to dbname) when the DBOptions were sanitized. Because of this setitng in the options file, it was not possible to rename/relocate a database directory after it had been created and use the existing options file.
After this change, the "wal_dir" option is only set under specific circumstances. Methods were added to the ImmutableDBOptions class to see if it is set and if it is set to something other than the dbname. Additionally, a method was added to retrieve the effective value of the WAL dir (either the option or the dbname/path).
Tests were added to the core and ldb to test that a database could be created and renamed without issue. Additional tests for various permutations of wal_dir were also added.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8582
Reviewed By: pdillinger, autopear
Differential Revision: D29881122
Pulled By: mrambacher
fbshipit-source-id: 67d3d033dc8813d59917b0a3fba2550c0efd6dfb
Summary:
- Added Type/CreateFromString
- Added ability to load EventListeners to DBOptions
- Since EventListeners did not previously have a Name(), defaulted to "". If there is no name, the listener cannot be loaded from the ObjectRegistry.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8473
Reviewed By: zhichao-cao
Differential Revision: D29901488
Pulled By: mrambacher
fbshipit-source-id: 2d3a4aa6db1562ac03e7ad41b360e3521d486254
Summary:
If the primary's CURRENT file is missing or inaccessible, the secondary should not hang
trying repeatedly to switch to the next MANIFEST.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8200
Test Plan: make check
Reviewed By: jay-zhuang
Differential Revision: D27840627
Pulled By: riversand963
fbshipit-source-id: 071fed97cbab1bc5cdefd1dc235e5cd406c174e1
Summary:
Try avoid expensive updating options operation if
`SetDBOptions()` does not change any option value.
Skip updating is not guaranteed, for example, changing `bytes_per_sync`
to `0` may still trigger updating, as the value could be sanitized.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8518
Test Plan: added unittest
Reviewed By: riversand963
Differential Revision: D29672639
Pulled By: jay-zhuang
fbshipit-source-id: b7931de62ceea6f1bdff0d1209adf1197d3ed1f4
Summary:
This PR is for https://github.com/facebook/rocksdb/issues/8453
We need to update `s = biter.status();` when `biter.status().IsIncomplete()` is true. By doing this, can fix the problem in issue.
Besides, we still need to update `db_statistics` in `get_context.ReportCounters()` before return back.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8485
Reviewed By: jay-zhuang
Differential Revision: D29604835
Pulled By: ajkr
fbshipit-source-id: c7f2f1cd058223ce1b507ec05d57cf264b9c9710
Summary:
In ```DBImpl::WriteImpl()```, we call ```PreprocessWrite()``` which, among other things, checks the BG error and returns it set. This return status is later on passed to ```WriteStatusCheck()```, which calls ```SetBGError()```. This results in a spurious call, and info logs, on every user write request. We should avoid passing the ```PreprocessWrite()``` return status to ```WriteStatusCheck()```, as the former would have called ```SetBGError()``` already if it encountered any new errors, such as error when creating a new WAL file.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8511
Test Plan: Run existing tests
Reviewed By: zhichao-cao
Differential Revision: D29639917
Pulled By: anand1976
fbshipit-source-id: 19234163969e1645dbeb273712aaf5cd9ea2b182
Summary:
Added BlobMetaData to ColumnFamilyMetaData and LiveBlobMetaData and DB API GetLiveBlobMetaData to retrieve it.
First pass at struct. More tests and maybe fields to come...
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8273
Reviewed By: ltamasi
Differential Revision: D29102400
Pulled By: mrambacher
fbshipit-source-id: 8a2383a4446328be6b91dced9841fdd3dfc80b73
Summary:
Add an argument to ldb to dump live file names, column families, and levels, `list_live_files_metadata`. The output shows all active SST file names, sorted first by column family and then by level. For each level the SST files are sorted alphabetically.
Typically, the output looks like this:
```
./ldb --db=/tmp/test_db list_live_files_metadata
Live SST Files:
===== Column Family: default =====
---------- level 0 ----------
/tmp/test_db/000069.sst
---------- level 1 ----------
/tmp/test_db/000064.sst
/tmp/test_db/000065.sst
/tmp/test_db/000066.sst
/tmp/test_db/000071.sst
---------- level 2 ----------
/tmp/test_db/000038.sst
/tmp/test_db/000039.sst
/tmp/test_db/000052.sst
/tmp/test_db/000067.sst
/tmp/test_db/000070.sst
------------------------------
```
Second, a flag was added `--sort_by_filename`, to change the layout of the output. When this flag is added to the command, the output shows all active SST files sorted by name, in front of which the LSM level and the column family are mentioned. With the same example, the following command would return:
```
./ldb --db=/tmp/test_db list_live_files_metadata --sort_by_filename
Live SST Files:
/tmp/test_db/000038.sst : level 2, column family 'default'
/tmp/test_db/000039.sst : level 2, column family 'default'
/tmp/test_db/000052.sst : level 2, column family 'default'
/tmp/test_db/000064.sst : level 1, column family 'default'
/tmp/test_db/000065.sst : level 1, column family 'default'
/tmp/test_db/000066.sst : level 1, column family 'default'
/tmp/test_db/000067.sst : level 2, column family 'default'
/tmp/test_db/000069.sst : level 0, column family 'default'
/tmp/test_db/000070.sst : level 2, column family 'default'
/tmp/test_db/000071.sst : level 1, column family 'default'
------------------------------
```
Thus, the user can either request to show the files by levels, or sorted by filenames.
This PR includes a simple Python unit test that makes sure the file name and level printed out by this new feature matches the one found with an existing feature, `dump_live_file`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8446
Reviewed By: akankshamahajan15
Differential Revision: D29320080
Pulled By: bjlemaire
fbshipit-source-id: 01fb7b5637c59010d74c80730a28d815994e7009
Summary:
This reverts commit 25be1ed66a.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8438
Test Plan: Run the impacted mysql test 40 times
Reviewed By: ajkr
Differential Revision: D29286247
Pulled By: jay-zhuang
fbshipit-source-id: d3bd056971a19a8b012d5d0295fa045c012b3c04
Summary:
`git diff origin/6.21.fb origin/6.22.fb -- HISTORY.md` looked odd.
This PR fixes it up by moving items from 6.21.0 to 6.22.0 that were
never in any 6.21 release. Also mentioned the background stat collection
fix under 6.22 (previously it was mentioned under 6.21 patch releases
only).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8441
Reviewed By: jay-zhuang
Differential Revision: D29304812
Pulled By: ajkr
fbshipit-source-id: 2a928a9518a1d6615321d5c2d1e22b17cbb59093
Summary:
`DeleteFilesInRange()` marks deleting files to `being_compacted`
before deleting, which may cause ongoing compactions report corruption
exception or ASSERT for debug build.
Adding the missing `ComputeCompactionScore()` when `being_compacted` is set.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8434
Test Plan: Unittest
Reviewed By: ajkr
Differential Revision: D29276127
Pulled By: jay-zhuang
fbshipit-source-id: f5b223e3c1fc6d821e100e3f3442bc70c1d50cf7
Summary:
**Summary**:
2 new statistics counters are added to RocksDB: `MEMTABLE_PAYLOAD_BYTES_AT_FLUSH` and `MEMTABLE_GARBAGE_BYTES_AT_FLUSH`. The former tracks how many raw bytes of useful data are present on the memtable at flush time, whereas the latter is tracks how many of these raw bytes are considered garbage, meaning that they ended up not being imported on the SSTables resulting from the flush operations.
**Unit test**: run `make db_flush_test -j$(nproc); ./db_flush_test` to run the unit test.
This executable includes 3 tests, that test support and correct stat calculations for workloads with inserts, deletes, and DeleteRanges. The parameters are set such that the workloads are performed on a single memtable, and a single SSTable is created as a result of the flush operation. The flush operation is manually called in the test file. The tests verify that the values of these 2 statistics counters introduced in this PR can be exactly predicted, showing that we have a full understanding of the underlying operations.
**Performance testing**:
`./db_bench -statistics -benchmarks=fillrandom -num=10000000` repeated 10 times.
Timing done using "date" function in a bash script.
_Results_:
Original Rocksdb fork: mean 66.6 sec, std 1.18 sec.
This feature branch: mean 67.4 sec, std 1.35 sec.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8411
Reviewed By: akankshamahajan15
Differential Revision: D29150629
Pulled By: bjlemaire
fbshipit-source-id: 7b3c2e86d50c6aa34fa50fd134282eacb543a5b1
Summary:
This PR prepopulates warm/hot data blocks which are already in memory
into block cache at the time of flush. On a flush, the data block that is
in memory (in memtables) get flushed to the device. If using Direct IO,
additional IO is incurred to read this data back into memory again, which
is avoided by enabling newly added option.
Right now, this is enabled only for flush for data blocks. We plan to
expand this option to cover compactions in the future and for other types
of blocks.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8242
Test Plan: Add new unit test
Reviewed By: anand1976
Differential Revision: D28521703
Pulled By: akankshamahajan15
fbshipit-source-id: 7219d6958821cedce689a219c3963a6f1a9d5f05
Summary:
This commit is for enabling `DBWithTTL` to use `DeteleRange` which it cannot before.
As (int32_t)Timestamp is suffixed to values in `DBWithTTL`, there is no reason that it
cannot use the common used api. I added `DeleteRangeCF` in `DBWithTTLImpl::Write`
so that we can use `DeteleRange` normally. When we run code like
`dbWithTtl->DeleteRange(start, end)`, it executes`WriteBatchInternal::DeleteRange`
internally. Intended to fix https://github.com/facebook/rocksdb/issues/7218
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8384
Test Plan: added corresponded testing logic to existing unit test
Reviewed By: jay-zhuang
Differential Revision: D29176734
fbshipit-source-id: 6874ed979fc08e1d138149d03653e43a75f0e0e6
Summary:
Marked the Ribbon filter and optimize_filters_for_memory features
as production-ready, each enabling memory savings for Bloom-like filters.
Use `NewRibbonFilterPolicy` in place of `NewBloomFilterPolicy` to use
Ribbon filters instead of Bloom, or `ribbonfilter` in place of
`bloomfilter` in configuration string.
Some small refactoring in db_stress.
Removed/refactored unused code in db_bench, in part preparing for future
default possibly being different from "disabled."
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8408
Test Plan:
Lots of prior automated, ad-hoc, and "real world" testing.
Updated tests for new API names. Quick db_bench test:
bloom fillrandom
77730 ops/sec
rocksdb.block.cache.filter.bytes.insert COUNT : 89929384
ribbon fillrandom
71492 ops/sec
rocksdb.block.cache.filter.bytes.insert COUNT : 64531384
Reviewed By: mrambacher
Differential Revision: D29140805
Pulled By: pdillinger
fbshipit-source-id: d742c922722421678f95ad85eeb0aaebc9f5e49a
Summary:
This reverts commit 9167ece586.
It was found to reliably trip a compaction picking conflict assertion in a MyRocks unit test. We don't understand why yet so reverting in the meantime.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8410
Test Plan: `make check -j48`
Reviewed By: jay-zhuang
Differential Revision: D29150300
Pulled By: ajkr
fbshipit-source-id: 2de8664f355d6da015e84e5fec2e3f90f49741c8
Summary:
The subcompaction boundary picking logic does not currently guarantee
that all user keys that differ only by timestamp get processed by the same
subcompaction. This can cause issues with the `CompactionIterator` state
machine: for instance, one subcompaction that processes a subset of such KVs
might drop a tombstone based on the KVs it sees, while in reality the
tombstone might not have been eligible to be optimized out.
(See also https://github.com/facebook/rocksdb/issues/6645, which adjusted the way compaction inputs are picked for the
same reason.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8393
Test Plan: Ran `make check` and the crash test script with timestamps enabled.
Reviewed By: jay-zhuang
Differential Revision: D29071635
Pulled By: ltamasi
fbshipit-source-id: f6c72442122b4e581871e096fabe3876a9e8a5a6
Levi Tamasi