Summary:
This pull request adds a README file and a blog post for the Advisor tool. It also adds the missing tests for some Optimizer modules. Some comments are added to the classes being tested for improved readability.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4201
Reviewed By: maysamyabandeh
Differential Revision: D9125311
Pulled By: poojam23
fbshipit-source-id: aefcf2f06eaa05490cc2834ef5aa6e21f0d1dc55
Summary:
`CollapsedRangeDelMap` internally uses seqno zero as a sentinel value to
denote a gap between range tombstones or the end of range tombstones. It
therefore expects to never have consecutive sentinel tombstones.
However, since `DeleteRange` is now supported in `SstFileWriter`, an
ingested file may contain range tombstones, and that ingested file may
be assigned global seqno zero. When such tombstones are added to the
collapsed map, they resemble sentinel tombstones due to having seqno
zero. Then, the invariant mentioned above about never having consecutive
sentinel tombstones can be violated.
The symptom of this violation was dereferencing the `end()` iterator
(#4204). The fix in this PR is to not add range tombstones with seqno
zero to the collapsed map. They're not needed anyways since they can't
possibly cover anything (in case of a key and a range tombstone with the
same seqno, the key is visible).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4216
Differential Revision: D9121716
Pulled By: ajkr
fbshipit-source-id: f5b78a70bea9527354603ea7ac8542a7e2b6a210
Summary:
A framework for tracing and replaying RocksDB operations.
A binary trace file is created by capturing the DB operations, and it can be replayed back at the same rate using db_bench.
- Column-families are supported
- Multi-threaded tracing is supported.
- TraceReader and TraceWriter are exposed to the user, so that tracing to various destinations can be enabled (say, to other messaging/logging services). By default, a FileTraceReader and FileTraceWriter are implemented to capture to a file and replay from it.
- This is not yet ideal to be enabled in production due to large performance overhead, but it can be safely tried out in a shadow setup, say, for analyzing RocksDB operations.
Currently supported DB operations:
- Writes:
-- Put
-- Merge
-- Delete
-- SingleDelete
-- DeleteRange
-- Write
- Reads:
-- Get (point lookups)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/3837
Differential Revision: D7974837
Pulled By: sagar0
fbshipit-source-id: 8ec65aaf336504bc1f6ed0feae67f6ed5ef97a72
Summary:
The cache line size was computed dynamically based on the length of the filter bits, and the number of cache-lines encoded in the footer. This calculation had to be dynamic in case users migrate their data between platforms with different cache line sizes. The downside, though, was bloom filter probing became expensive as it did integer mod and division.
However, since we know all possible cache line sizes are powers of two, we should be able to use bit shift to find the cache line, and bitwise-and to find the bit within the cache line. To do this, we compute the log-base-two of cache line size in the constructor, and use that in bitwise operations to replace division/mod.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4071
Differential Revision: D8684067
Pulled By: ajkr
fbshipit-source-id: 50298872fba5acd01e8269cd7abcc51a095e0f61
Summary:
Making generation of column families and keys virtual function so that
subclasses of StressTest can override them to provide custom parameter
generation for more flexibility. This will be useful for future tests.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4046
Differential Revision: D9073382
Pulled By: riversand963
fbshipit-source-id: 2754f0fdfa5c24d95c1f92d4944bc479552fb665
Summary:
RocksDB used to store global_seqno in external SST files written by
SstFileWriter. During file ingestion, RocksDB uses `pwrite` to update the
`global_seqno`. Since random write is not supported in some non-POSIX compliant
file systems, external SST file ingestion is not supported on these file
systems. To address this limitation, we no longer update `global_seqno` during
file ingestion. Later RocksDB uses the MANIFEST and other information in table
properties to deduce global seqno for externally-ingested SST files.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4172
Differential Revision: D8961465
Pulled By: riversand963
fbshipit-source-id: 4382ec85270a96be5bc0cf33758ca2b167b05071
Summary:
Added DataBlockIndexType option in BlockBasedTableOptions.
```
enum DataBlockIndexType : char {
kDataBlockBinarySearch = 0, // traditional block type
kDataBlockHashIndex = 1, // additional hash index appended to the end.
};
```
The default type is the traditional binary seek option: `kDataBlockBinarySearch`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4150
Differential Revision: D8895958
Pulled By: fgwu
fbshipit-source-id: 480adef48104cf11d30db3bad9a73f98b4a80c10
Summary:
If crash happen after a hard link established, Recover function may reuse the file number that has already assigned to the internal file, and this will overwrite the external file. To protect the external file, we have to make sure the file number will never being reused.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4099
Differential Revision: D9034092
Pulled By: riversand963
fbshipit-source-id: 3f1a737440b86aa2ef01673e5013aacbb7c33e28
Summary:
The inline doc was incorrectly mentioned a return status while the function does not return a value.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4196
Differential Revision: D9030927
Pulled By: maysamyabandeh
fbshipit-source-id: 07c34dc6bf521021bf790ac1bfedb676171129ec
Summary:
max_total_wal_size takes effect only when there are more than one column families. The patch clarify that in the inline docs
Closes https://github.com/facebook/rocksdb/issues/4180
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4194
Differential Revision: D9028767
Pulled By: maysamyabandeh
fbshipit-source-id: 8d730ca7f15e76e7ee9ff88b2b48030b2d1b7078
Summary:
In https://github.com/facebook/rocksdb/pull/3934 we introduced advisor scripts that make suggestions in the config options based on the log file and stats from a run of rocksdb. The optimizer runs the advisor on a benchmark application in a loop and automatically applies the suggested changes until the config options are optimized. This is a work in progress and the patch is the initial skeleton for the optimizer. The sample application that is run in the loop is currently dbbench.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4169
Reviewed By: maysamyabandeh
Differential Revision: D9023671
Pulled By: poojam23
fbshipit-source-id: a6192d475c462cf6eb2b316716f97cb400fcb64d
Summary:
Usually when using cscope, the query results contain a lot of function calls in test, making it hard to browse. So this PR aims to provide an option to exclude test source files.
Add a new PHONY target, tags0, to exclude test source files while using cscope.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4190
Differential Revision: D9015901
Pulled By: riversand963
fbshipit-source-id: ea9a45756ccff5b26344d37e9ff1c02c5d9736d6
Summary:
995fcf7573 has a bug: ReleaseFileNumberFromPendingOutputs() added is not protected by the DB mutex. Fix it by grabbing the lock for this operation.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4189
Differential Revision: D9015447
Pulled By: siying
fbshipit-source-id: b8506e09a96c3f95a6fe32b5ca5fcdb9bee88937
Summary:
92ee3350e0 introduces an out-of-bound check in BlockBasedTableIterator::Valid(). However, this flag is not reset when re-seeking in backward direction. This caused the iterator to be invalide by mistake. Fix it by always resetting the out-of-bound flag in every seek.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4187
Differential Revision: D8996600
Pulled By: siying
fbshipit-source-id: b6235ea614f71381e50e7904c4fb036300604ac1
Summary:
Given that we have cut 5.15, we should bump the version number to the next
version, i.e. 5.16.
Also update HISTORY.md
cc sagar0
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4176
Differential Revision: D8977965
Pulled By: riversand963
fbshipit-source-id: 481d75d2f446946f0eb2afb7e94ef894c8c87e1e
Summary:
The first step of the `DataBlockHashIndex` implementation. A string based hash table is implemented and unit-tested.
`DataBlockHashIndexBuilder`: `Add()` takes pairs of `<key, restart_index>`, and formats it into a string when `Finish()` is called.
`DataBlockHashIndex`: initialized by the formatted string, and can interpret it as a hash table. Lookup for a key is supported by iterator operation.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4139
Reviewed By: sagar0
Differential Revision: D8866764
Pulled By: fgwu
fbshipit-source-id: 7f015f0098632c65979a22898a50424384730b10
Summary:
This adds support for writing unprepared batches based on size defined in `TransactionOptions::max_write_batch_size`. This is done by overriding methods that modify data (Put/Delete/SingleDelete/Merge) and checking first if write batch size has exceeded threshold. If so, the write batch is written to DB as an unprepared batch.
Support for Commit/Rollback for unprepared batch is added as well. This has been done by simply extending the WritePrepared Commit/Rollback logic to take care of all unprep_seq numbers either when updating prepare heap, or adding to commit map. For updating the commit map, this logic exists inside `WriteUnpreparedCommitEntryPreReleaseCallback`.
A test change was also made to have transactions unregister themselves when committing without prepare. This is because with write unprepared, there may be unprepared entries (which act similarly to prepared entries) already when a commit is done without prepare.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4104
Differential Revision: D8785717
Pulled By: lth
fbshipit-source-id: c02006e281ec1ce00f628e2a7beec0ee73096a91
Summary:
The member msgs of class Status contains all types of status messages.
When users dump a Status object, msgs will confuse users. So move it out
of class Status by making it as file-local static variable.
Closes#3831 .
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4144
Differential Revision: D8941419
Pulled By: sagar0
fbshipit-source-id: 56b0510258465ff26db15aa6b04e01532e053e3d
Summary:
db_stress doesn't cover upper or lower bound in iterators. Try to cover it by randomly assigning a random one. Also in prefix scan tests, with 50% of the chance, set next prefix as the upper bound.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4162
Differential Revision: D8953507
Pulled By: siying
fbshipit-source-id: f0f04e9cb6c07cbebbb82b892ca23e0daeea708b
Summary:
Currently in `Version::Get` when reporting ticker stats stored in `GetContext`, there is a big for-loop through all `Ticker` which adds unnecessary cost to overall CPU usage. We can optimize by storing only ticker values that are used in `Get()` calls in a new struct `GetContextStats` since only a small fraction of all tickers are used in `Get()` calls. For comparison, with the new approach we only need to visit 17 values while old approach will require visiting 100+ `Ticker`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/3490
Differential Revision: D6969154
Pulled By: miasantreble
fbshipit-source-id: fc27072965a3a94125a3e6883d20dafcf5b84029
Summary:
When running the tracing and analyzing, I found that MergeRandom benchmark in db_bench only access the default column family even the -num_column_families is specified > 1.
changes: Using the db_with_cfh as DB to randomly select the column family to execute the Merge operation if -num_column_families is specified > 1.
Tested with make asan_check and verified in tracing
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4155
Differential Revision: D8907888
Pulled By: zhichao-cao
fbshipit-source-id: 2b4bc8fe0e99c8f262f5be6b986c7025d62cf850
Summary:
Lint is not happy with some new code recently committed. Format them.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4161
Differential Revision: D8940582
Pulled By: siying
fbshipit-source-id: c9b43b1ef8c88b5e923911058b44eb77234b36b7
Summary:
Right now we use one hard-coded prefetch size to prefetch data from the tail of the SST files. However, this may introduce a waste for some use cases, while not efficient for others.
Introduce a way to adjust this prefetch size by tracking 32 recent times, and pick a value with which the wasted read is less than 10%
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4156
Differential Revision: D8916847
Pulled By: siying
fbshipit-source-id: 8413f9eb3987e0033ed0bd910f83fc2eeaaf5758
Summary:
The properties meta-block should come at the end since we always need to
read it when opening a file, unlike index/filter/other meta-blocks, which
are sometimes read depending on the user's configuration. This ordering
will allow us to (in a future PR) do a small readahead on the end of the file
to read properties and meta-index blocks with one I/O.
The bulk of this PR is a refactoring of the `BlockBasedTableBuilder::Finish`
function. It was previously too large with inconsistent error handling, which
made it difficult to change. So I broke it up into one function per meta-block
write, and tried to make error handling consistent within those functions.
Then reordering the metablocks was trivial -- just reorder the calls to these
helper functions.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4158
Differential Revision: D8921705
Pulled By: ajkr
fbshipit-source-id: 96c9cc3182eb1adf11af46adab79dbeba7b12fcc
Summary:
PR #3944 introduces group commit of `VersionEdit` in MANIFEST. The
implementation has a bug. When updating the log file number of each column
family, we must consider only `VersionEdit`s that operate on the same column
family. Otherwise, a column family may accidentally set its log file number
higher than actual value, indicating that log files with smaller file number
will be ignored, thus causing some updates to be lost.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4157
Differential Revision: D8916650
Pulled By: riversand963
fbshipit-source-id: 8f456cf688f17bf35ad87b38e30e899aa162f201
Summary:
In all cases during `BlockBasedTable::Open`, we issue at least three read requests to the file's tail: (1) footer, (2) metaindex block, and (3) properties block. Depending on the config, we may also read other metablocks like filter and index.
This PR issues smaller readahead when we expect to do only the three necessary reads mentioned above. Then, 4KB should be enough (ignoring the case where there are lots of user-defined properties). We can keep doing 512KB readahead when additional reads are expected.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4159
Differential Revision: D8924002
Pulled By: ajkr
fbshipit-source-id: cfc713275de4d05ce11f18571f1d72e27ccd3356
Summary: Windows requires new/delete for memory allocations to be overriden. Refactor to be less intrusive.
Differential Revision: D8878047
Pulled By: siying
fbshipit-source-id: 35f2b5fec2f88ea48c9be926539c6469060aab36
Summary:
I am temporarily disabling DBFlushTest.SyncFail and DBTest.GroupCommitTest tests on Travis until we figure out the root-cause. These tests will still continue to run locally though.
I haven't been able to reproduce these failures locally so far (even on a [local Travis environment](https://docs.travis-ci.com/user/common-build-problems/#Troubleshooting-Locally-in-a-Docker-Image) ).
These tests are failing way too frequently causing everyone to wonder why their PR failed on travis, and waste time in debugging.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4154
Differential Revision: D8907258
Pulled By: sagar0
fbshipit-source-id: f40068b16e9245fb3791b6a4796435d1ce1ed205
Summary:
Adding the string "PERF_CONTEXT:" before the perf_context stats are printed. Setting the filter policy if it's a block based table even when options are being loaded from the provided FLAGS_options_file.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4153
Differential Revision: D8905517
Pulled By: poojam23
fbshipit-source-id: 5956ed7882d39ec8ae654d5dadeb88727a36f0dd
Summary:
Fixing compilation, unsatisfied link exceptions (updated list of files that needs to be linked) and warnings for Windows build.
```C++
//MSVC 2015 does not support dynamic arrays like:
rocksdb::Slice key_parts[jkey_parts_len];
//I have converted to:
std::vector<rocksdb::Slice> key_parts;
```
Also reusing `free_key_parts` that does the same as `free_key_value_parts` that was removed.
Java elapsedTime unit test increase of sleep to 2 ms. Otherwise it was failing.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4015
Differential Revision: D8558215
Pulled By: sagar0
fbshipit-source-id: d3c34f846343f9218424da2402a2bd367bbd0aa2
Summary:
Users sometime see their memtable size far smaller than expected. They probably have hit a fragementation of shard blocks. Cap their size anyway to reduce the impact of problem. 128KB is conservative so I don't imagine it can cause any performance problem.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4147
Differential Revision: D8886706
Pulled By: siying
fbshipit-source-id: 8528a2a4196aa4457274522e2565fd3ff28f621e
Summary:
Fix a minor data race in DBSSTTest.DeleteSchedulerMultipleDBPaths reported by TSAN
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4146
Differential Revision: D8880945
Pulled By: siying
fbshipit-source-id: 25c632f685757735c59ad4ff26b2f346a443a446
Summary:
Fix the issue when pipelined write is enabled, writers can get stuck indefinitely and not able to finish the write. It can show with the following example: Assume there are 4 writers W1, W2, W3, W4 (W1 is the first, W4 is the last).
T1: all writers pending in WAL writer queue:
WAL writer queue: W1, W2, W3, W4
memtable writer queue: empty
T2. W1 finish WAL writer and move to memtable writer queue:
WAL writer queue: W2, W3, W4,
memtable writer queue: W1
T3. W2 and W3 finish WAL write as a batch group. W2 enter ExitAsBatchGroupLeader and move the group to memtable writer queue, but before wake up next leader.
WAL writer queue: W4
memtable writer queue: W1, W2, W3
T4. W1, W2, W3 finish memtable write as a batch group. Note that W2 still in the previous ExitAsBatchGroupLeader, although W1 have done memtable write for W2.
WAL writer queue: W4
memtable writer queue: empty
T5. The thread corresponding to W3 create another writer W3' with the same address as W3.
WAL writer queue: W4, W3'
memtable writer queue: empty
T6. W2 continue with ExitAsBatchGroupLeader. Because the address of W3' is the same as W3, the last writer in its group, it thinks there are no pending writers, so it reset newest_writer_ to null, emptying the queue. W4 and W3' are deleted from the queue and will never be wake up.
The issue exists since pipelined write was introduced in 5.5.0.
Closes#3704
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4143
Differential Revision: D8871599
Pulled By: yiwu-arbug
fbshipit-source-id: 3502674e51066a954a0660257e24ac588f815e2a
Summary:
If bulkload fails for an input error, the pending output file number wasn't released. This bug can cause all future files with larger number than the current number won't be deleted, even they are compacted. This commit fixes the bug.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4145
Differential Revision: D8877900
Pulled By: siying
fbshipit-source-id: 080be92a23d43305ca1e13fe1c06eb4cd0b01466
Summary:
Added Get Put Encode Decode support for Fixed16 (uint16_t). Unit test added in `coding_test.cc`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4142
Differential Revision: D8873516
Pulled By: fgwu
fbshipit-source-id: 331913e0a9a8fe9c95606a08e856e953477d64d3
Summary:
We forgot to dump FIFO and Universal compaction options to the LOG when any option was dynamically changed via `SetOptions` API. Now added those options also to `MutableCFOptions::Dump`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4140
Differential Revision: D8865634
Pulled By: sagar0
fbshipit-source-id: 05a93e26ab8e72fec6249acccd09b0eb3e1ef0ac
Summary:
Refactor IndexBlockIter to reduce conditional branches on key_includes_seq_. IndexBlockIter::Prev is also separated from DataBlockIter::Prev, not to cache the prev entries as they are of less importance when iterating over the index block.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4141
Differential Revision: D8866437
Pulled By: maysamyabandeh
fbshipit-source-id: fdac76880426fc2be7d3c6354c09ab98f6657d4b
Summary:
Some logic only related to IndexBlockIter is separated from BlockIter to IndexBlockIter. This is done by writing an exclusive Seek() and SeekForPrev() for DataBlockIter, and all metadata block iter and tombstone block iter now use data block iter. Dealing with the BinarySeek() sharing problem by passing in the comparator to use.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4136
Reviewed By: maysamyabandeh
Differential Revision: D8859673
Pulled By: siying
fbshipit-source-id: 703e5e6824b82b7cbf4721f3594b94127797ca9e
Summary:
Fixes#3391.
This change adds a `DeleteRange` method to `SstFileWriter` and adds
support for ingesting SSTs with range deletion tombstones. This is
important for applications that need to atomically ingest SSTs while
clearing out any existing keys in a given key range.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/3778
Differential Revision: D8821836
Pulled By: anand1976
fbshipit-source-id: ca7786c1947ff129afa703dab011d524c7883844
Summary:
Our "rocksdb.sst.read.micros" stat includes time spent waiting for rate limiter. It probably only affects people rate limiting compaction reads, which is fairly rare.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4102
Differential Revision: D8848506
Pulled By: miasantreble
fbshipit-source-id: 01258ac5ae56e4eee372978cfc9143a6869f8bfc
Summary:
Do not consider the range tombstone sentinel key as causing 2 adjacent
sstables in a level to overlap. When a range tombstone's end key is the
largest key in an sstable, the sstable's end key is so to a "sentinel"
value that is the smallest key in the next sstable with a sequence
number of kMaxSequenceNumber. This "sentinel" is guaranteed to not
overlap in internal-key space with the next sstable. Unfortunately,
GetOverlappingFiles uses user-keys to determine overlap and was thus
considering 2 adjacent sstables in a level to overlap if they were
separated by this sentinel key. This in turn would cause compactions to
be larger than necessary.
Note that this conflicts with
https://github.com/facebook/rocksdb/pull/2769 and cases
`DBRangeDelTest.CompactionTreatsSplitInputLevelDeletionAtomically` to
fail.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4050
Differential Revision: D8844423
Pulled By: ajkr
fbshipit-source-id: df3f9f1db8f4cff2bff77376b98b83c2ae1d155b
Summary:
The patch makes sure that two parallel test threads will operate on different db paths. This enables using open source tools such as gtest-parallel to run the tests of a file in parallel.
Example: ``` ~/gtest-parallel/gtest-parallel ./table_test```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4135
Differential Revision: D8846653
Pulled By: maysamyabandeh
fbshipit-source-id: 799bad1abb260e3d346bcb680d2ae207a852ba84
Summary:
Picked up a task to convert this to use the gtest framework. It can't be this simple, can it?
It works, but should all the std::cout be removed?
```
[$] ~/git/rocksdb [gft !]: ./merge_test
[==========] Running 2 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 2 tests from MergeTest
[ RUN ] MergeTest.MergeDbTest
Test read-modify-write counters...
a: 3
1
2
a: 3
b: 1225
3
Compaction started ...
Compaction ended
a: 3
b: 1225
Test merge-based counters...
a: 3
1
2
a: 3
b: 1225
3
Test merge in memtable...
a: 3
1
2
a: 3
b: 1225
3
Test Partial-Merge
Test merge-operator not set after reopen
[ OK ] MergeTest.MergeDbTest (93 ms)
[ RUN ] MergeTest.MergeDbTtlTest
Opening database with TTL
Test read-modify-write counters...
a: 3
1
2
a: 3
b: 1225
3
Compaction started ...
Compaction ended
a: 3
b: 1225
Test merge-based counters...
a: 3
1
2
a: 3
b: 1225
3
Test merge in memtable...
Opening database with TTL
a: 3
1
2
a: 3
b: 1225
3
Test Partial-Merge
Opening database with TTL
Opening database with TTL
Opening database with TTL
Opening database with TTL
Test merge-operator not set after reopen
[ OK ] MergeTest.MergeDbTtlTest (97 ms)
[----------] 2 tests from MergeTest (190 ms total)
[----------] Global test environment tear-down
[==========] 2 tests from 1 test case ran. (190 ms total)
[ PASSED ] 2 tests.
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4114
Differential Revision: D8822886
Pulled By: gfosco
fbshipit-source-id: c299d008e883c3bb911d2b357a2e9e4423f8e91a
