Summary:
The current BlobDB garbage collection logic works by relocating the valid
blobs from the oldest blob files as they are encountered during compaction,
and cleaning up blob files once they contain nothing but garbage. However,
with sufficiently skewed workloads, it is theoretically possible to end up in a
situation when few or no compactions get scheduled for the SST files that contain
references to the oldest blob files, which can lead to increased space amp due
to the lack of GC.
In order to efficiently handle such workloads, the patch adds a new BlobDB
configuration option called `blob_garbage_collection_force_threshold`,
which signals to BlobDB to schedule targeted compactions for the SST files
that keep alive the oldest batch of blob files if the overall ratio of garbage in
the given blob files meets the threshold *and* all the given blob files are
eligible for GC based on `blob_garbage_collection_age_cutoff`. (For example,
if the new option is set to 0.9, targeted compactions will get scheduled if the
sum of garbage bytes meets or exceeds 90% of the sum of total bytes in the
oldest blob files, assuming all affected blob files are below the age-based cutoff.)
The net result of these targeted compactions is that the valid blobs in the oldest
blob files are relocated and the oldest blob files themselves cleaned up (since
*all* SST files that rely on them get compacted away).
These targeted compactions are similar to periodic compactions in the sense
that they force certain SST files that otherwise would not get picked up to undergo
compaction and also in the sense that instead of merging files from multiple levels,
they target a single file. (Note: such compactions might still include neighboring files
from the same level due to the need of having a "clean cut" boundary but they never
include any files from any other level.)
This functionality is currently only supported with the leveled compaction style
and is inactive by default (since the default value is set to 1.0, i.e. 100%).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8994
Test Plan: Ran `make check` and tested using `db_bench` and the stress/crash tests.
Reviewed By: riversand963
Differential Revision: D31489850
Pulled By: ltamasi
fbshipit-source-id: 44057d511726a0e2a03c5d9313d7511b3f0c4eab
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:
Changes the API of the MemPurge process: the `bool experimental_allow_mempurge` and `experimental_mempurge_policy` flags have been replaced by a `double experimental_mempurge_threshold` option.
This change of API reflects another major change introduced in this PR: the MemPurgeDecider() function now works by sampling the memtables being flushed to estimate the overall amount of useful payload (payload minus the garbage), and then compare this useful payload estimate with the `double experimental_mempurge_threshold` value.
Therefore, when the value of this flag is `0.0` (default value), mempurge is simply deactivated. On the other hand, a value of `DBL_MAX` would be equivalent to always going through a mempurge regardless of the garbage ratio estimate.
At the moment, a `double experimental_mempurge_threshold` value else than 0.0 or `DBL_MAX` is opnly supported`with the `SkipList` memtable representation.
Regarding the sampling, this PR includes the introduction of a `MemTable::UniqueRandomSample` function that collects (approximately) random entries from the memtable by using the new `SkipList::Iterator::RandomSeek()` under the hood, or by iterating through each memtable entry, depending on the target sample size and the total number of entries.
The unit tests have been readapted to support this new API.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8628
Reviewed By: pdillinger
Differential Revision: D30149315
Pulled By: bjlemaire
fbshipit-source-id: 1feef5390c95db6f4480ab4434716533d3947f27
Summary:
Implement an experimental feature called "MemPurge", which consists in purging "garbage" bytes out of a memtable and reuse the memtable struct instead of making it immutable and eventually flushing its content to storage.
The prototype is by default deactivated and is not intended for use. It is intended for correctness and validation testing. At the moment, the "MemPurge" feature can be switched on by using the `options.experimental_allow_mempurge` flag. For this early stage, when the allow_mempurge flag is set to `true`, all the flush operations will be rerouted to perform a MemPurge. This is a temporary design decision that will give us the time to explore meaningful heuristics to use MemPurge at the right time for relevant workloads . Moreover, the current MemPurge operation only supports `Puts`, `Deletes`, `DeleteRange` operations, and handles `Iterators` as well as `CompactionFilter`s that are invoked at flush time .
Three unit tests are added to `db_flush_test.cc` to test if MemPurge works correctly (and checks that the previously mentioned operations are fully supported thoroughly tested).
One noticeable design decision is the timing of the MemPurge operation in the memtable workflow: for this prototype, the mempurge happens when the memtable is switched (and usually made immutable). This is an inefficient process because it implies that the entirety of the MemPurge operation happens while holding the db_mutex. Future commits will make the MemPurge operation a background task (akin to the regular flush operation) and aim at drastically enhancing the performance of this operation. The MemPurge is also not fully "WAL-compatible" yet, but when the WAL is full, or when the regular MemPurge operation fails (or when the purged memtable still needs to be flushed), a regular flush operation takes place. Later commits will also correct these behaviors.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8454
Reviewed By: anand1976
Differential Revision: D29433971
Pulled By: bjlemaire
fbshipit-source-id: 6af48213554e35048a7e03816955100a80a26dc5
Summary:
Add new C APIs to create the JemallocNodumpAllocator and set it on a Cache object.
`make test` passes with and without `DISABLE_JEMALLOC=1`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8178
Reviewed By: jay-zhuang
Differential Revision: D27944631
Pulled By: ajkr
fbshipit-source-id: 2531729aa285a8985c58f22f093c4d53029c4a7b
Summary:
Added the Blob option settings from the AdvancedColmnFamilyOptions to the C API.
There are no tests for getting/setting options in the C API currently, hence no specific test plans. Should there be a some?
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8148
Reviewed By: ltamasi
Differential Revision: D27568495
Pulled By: mrambacher
fbshipit-source-id: 3a52b784467ea2c4bc58be5f75c5d41f0a5c55d6
Summary:
The snapshot structure returned by rocksdb_transaction_get_snapshot is
supposed to be freed by calling rocksdb_free(), so allocate using malloc
rather than new. Fixes https://github.com/facebook/rocksdb/issues/6112
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8114
Reviewed By: akankshamahajan15
Differential Revision: D27362923
Pulled By: anand1976
fbshipit-source-id: e93a8b1ffe26dafbe22529907f72b796ae971214
Summary:
For dictionary compression, we need to collect some representative samples of the data to be compressed, which we use to either generate or train (when `CompressionOptions::zstd_max_train_bytes > 0`) a dictionary. Previously, the strategy was to buffer all the data blocks during flush, and up to the target file size during compaction. That strategy allowed us to randomly pick samples from as wide a range as possible that'd be guaranteed to land in a single output file.
However, some users try to make huge files in memory-constrained environments, where this strategy can cause OOM. This PR introduces an option, `CompressionOptions::max_dict_buffer_bytes`, that limits how much data blocks are buffered before we switch to unbuffered mode (which means creating the per-SST dictionary, writing out the buffered data, and compressing/writing new blocks as soon as they are built). It is not strict as we currently buffer more than just data blocks -- also keys are buffered. But it does make a step towards giving users predictable memory usage.
Related changes include:
- Changed sampling for dictionary compression to select unique data blocks when there is limited availability of data blocks
- Made use of `BlockBuilder::SwapAndReset()` to save an allocation+memcpy when buffering data blocks for building a dictionary
- Changed `ParseBoolean()` to accept an input containing characters after the boolean. This is necessary since, with this PR, a value for `CompressionOptions::enabled` is no longer necessarily the final component in the `CompressionOptions` string.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7970
Test Plan:
- updated `CompressionOptions` unit tests to verify limit is respected (to the extent expected in the current implementation) in various scenarios of flush/compaction to bottommost/non-bottommost level
- looked at jemalloc heap profiles right before and after switching to unbuffered mode during flush/compaction. Verified memory usage in buffering is proportional to the limit set.
Reviewed By: pdillinger
Differential Revision: D26467994
Pulled By: ajkr
fbshipit-source-id: 3da4ef9fba59974e4ef40e40c01611002c861465
Summary:
This is a PR generated **semi-automatically** by an internal tool to remove unused includes and `using` statements.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7604
Test Plan: make check
Reviewed By: ajkr
Differential Revision: D24579392
Pulled By: riversand963
fbshipit-source-id: c4bfa6c6b08da1de186690d37eb73d8fff45aecd
Summary:
This PR creates `rocksdb_open_column_families_with_ttl` which allows C API users to open a DBWithTLL with column families.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7314
Reviewed By: cheng-chang
Differential Revision: D23430287
Pulled By: ajkr
fbshipit-source-id: 307aa21d170d1402653263a91f6f832ef76afba0
Summary:
Added setting of zstd_max_train_bytes compression option parameter to c interop.
rocksdb_options_set_bottommost_compression_options was using bool parameter and thus not exported, updated it to unsigned char and added to c.h as well.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6796
Reviewed By: cheng-chang
Differential Revision: D21611471
Pulled By: ajkr
fbshipit-source-id: caaaf153de934837ad9af283c7f8c025ff0b0cf5
Summary:
Adding a C API function to set `row_cache` on `rocksdb_options_t` as this functionality is missing.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6442
Differential Revision: D20036813
Pulled By: riversand963
fbshipit-source-id: c1fa95ea343345fbc1e57961d0d048e0e79be373
Summary:
When dynamically linking two binaries together, different builds of RocksDB from two sources might cause errors. To provide a tool for user to solve the problem, the RocksDB namespace is changed to a flag which can be overridden in build time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6433
Test Plan: Build release, all and jtest. Try to build with ROCKSDB_NAMESPACE with another flag.
Differential Revision: D19977691
fbshipit-source-id: aa7f2d0972e1c31d75339ac48478f34f6cfcfb3e
Summary:
When paranoid_checks is on, DBImpl::CheckConsistency() iterates over all sst files and calls Env::GetFileSize() for each of them. As far as I could understand, this is pretty arbitrary and doesn't affect correctness - if filesystem doesn't corrupt fsynced files, the file sizes will always match; if it does, it may as well corrupt contents as well as sizes, and rocksdb doesn't check contents on open.
If there are thousands of sst files, getting all their sizes takes a while. If, on top of that, Env is overridden to use some remote storage instead of local filesystem, it can be *really* slow and overload the remote storage service. This PR adds an option to not do GetFileSize(); instead it does GetChildren() for parent directory to check that all the expected sst files are at least present, but doesn't check their sizes.
We can't just disable paranoid_checks instead because paranoid_checks do a few other important things: make the DB read-only on write errors, print error messages on read errors, etc.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6353
Test Plan: ran the added sanity check unit test. Will try it out in a LogDevice test cluster where the GetFileSize() calls are causing a lot of trouble.
Differential Revision: D19656425
Pulled By: al13n321
fbshipit-source-id: c2c421b367633033760d1f56747bad206d1fbf82
Summary:
Unit test names, together with other components, are used to create log files
during some internal testing. Overly long names cause infra failure due to file
names being too long.
Look for internal tests.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6352
Differential Revision: D19649307
Pulled By: riversand963
fbshipit-source-id: 6f29de096e33c0eaa87d9c8702f810eda50059e7
Summary:
This PR adds a `rocksdb_options_set_atomic_flush` function to the C API.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6307
Differential Revision: D19451313
Pulled By: ltamasi
fbshipit-source-id: 750495642ef55b1ea7e13477f85c38cd6574849c
Summary:
This makes it easier to call the functions from Rust as otherwise they require mutable types.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6283
Differential Revision: D19349991
Pulled By: wqfish
fbshipit-source-id: e8da7a75efe8cd97757baef8ca844a054f2519b4
Summary:
Fix an error message when CURRENT is not found.
Test plan (dev server)
```
make check
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6264
Differential Revision: D19300699
Pulled By: riversand963
fbshipit-source-id: 303fa206386a125960ecca1dbdeff07422690caf
Summary:
It seems that the C-API doesn't expose the range delete functionality at the moment, so add the API.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6259
Differential Revision: D19290320
Pulled By: pdillinger
fbshipit-source-id: 3f403a4c3446d2042d55f1ece7cdc9c040f40c27
Summary:
Formatter somehow complains some recent lines changed. Apply them to make the formatter happy.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6138
Test Plan: See CI passes.
Differential Revision: D18895950
fbshipit-source-id: 7d1696cf3e3a682bc10a30cdca748a23c6565255
Summary:
Add overrides needed in FilterPolicy wrapper to fix
rocksdb_filterpolicy_create_bloom_full (see issue https://github.com/facebook/rocksdb/issues/6129). Re-enabled
assertion in BloomFilterPolicy::CreateFilter that was being violated.
Expanded c_test to identify Bloom filter implementations by FP counts.
(Without the fix, updated test will trigger assertion and fail otherwise
without the assertion.)
Fixes https://github.com/facebook/rocksdb/issues/6129
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6132
Test Plan: updated c_test, also run under valgrind.
Differential Revision: D18864911
Pulled By: pdillinger
fbshipit-source-id: 08e81d7b5368b08e501cd402ef5583f2650c19fa
Summary:
Adds two missing functions to the C-API:
- `rocksdb_block_based_options_set_data_block_index_type`
- `rocksdb_block_based_options_set_data_block_hash_ratio`
This enables users in other languages to enjoy the new(-ish) feature.
The changes here are partially overlapping with [another PR](https://github.com/facebook/rocksdb/pull/5630) but are more focused on the DataBlock indexing options.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6101
Differential Revision: D18765639
fbshipit-source-id: 4a8947e71b179f26fa1eb83c267dd47ee64ac3b3
Summary:
MyRocks currently sets `max_write_buffer_number_to_maintain` in order to maintain enough history for transaction conflict checking. The effectiveness of this approach depends on the size of memtables. When memtables are small, it may not keep enough history; when memtables are large, this may consume too much memory.
We are proposing a new way to configure memtable list history: by limiting the memory usage of immutable memtables. The new option is `max_write_buffer_size_to_maintain` and it will take precedence over the old `max_write_buffer_number_to_maintain` if they are both set to non-zero values. The new option accounts for the total memory usage of flushed immutable memtables and mutable memtable. When the total usage exceeds the limit, RocksDB may start dropping immutable memtables (which is also called trimming history), starting from the oldest one.
The semantics of the old option actually works both as an upper bound and lower bound. History trimming will start if number of immutable memtables exceeds the limit, but it will never go below (limit-1) due to history trimming.
In order the mimic the behavior with the new option, history trimming will stop if dropping the next immutable memtable causes the total memory usage go below the size limit. For example, assuming the size limit is set to 64MB, and there are 3 immutable memtables with sizes of 20, 30, 30. Although the total memory usage is 80MB > 64MB, dropping the oldest memtable will reduce the memory usage to 60MB < 64MB, so in this case no memtable will be dropped.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5022
Differential Revision: D14394062
Pulled By: miasantreble
fbshipit-source-id: 60457a509c6af89d0993f988c9b5c2aa9e45f5c5
