Summary:
Remove the redundant PartitionedFilterBlockBuilder::num_added_ and ::NumAdded since the parent class, FullFilterBlockBuilder, already provides them.
Also rename filters_in_partition_ and filters_per_partition_ to keys_added_to_partition_ and keys_per_partition_ to improve readability.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6299
Test Plan: make check
Differential Revision: D19413278
Pulled By: pdillinger
fbshipit-source-id: 04926ee7874477d659cb2b6ae03f2d995fb747e5
Summary:
With many millions of keys, the old Bloom filter implementation
for the block-based table (format_version <= 4) would have excessive FP
rate due to the limitations of feeding the Bloom filter with a 32-bit hash.
This change computes an estimated inflated FP rate due to this effect
and warns in the log whenever an SST filter is constructed (almost
certainly a "full" not "partitioned" filter) that exceeds 1.5x FP rate
due to this effect. The detailed condition is only checked if 3 million
keys or more have been added to a filter, as this should be a lower
bound for common bits/key settings (< 20).
Recommended remedies include smaller SST file size, using
format_version >= 5 (for new Bloom filter), or using partitioned
filters.
This does not change behavior other than generating warnings for some
constructed filters using the old implementation.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6317
Test Plan:
Example with warning, 15M keys @ 15 bits / key: (working_mem_size_mb is just to stop after building one filter if it's large)
$ ./filter_bench -quick -impl=0 -working_mem_size_mb=1 -bits_per_key=15 -average_keys_per_filter=15000000 2>&1 | grep 'FP rate'
[WARN] [/block_based/filter_policy.cc:292] Using legacy SST/BBT Bloom filter with excessive key count (15.0M @ 15bpk), causing estimated 1.8x higher filter FP rate. Consider using new Bloom with format_version>=5, smaller SST file size, or partitioned filters.
Predicted FP rate %: 0.766702
Average FP rate %: 0.66846
Example without warning (150K keys):
$ ./filter_bench -quick -impl=0 -working_mem_size_mb=1 -bits_per_key=15 -average_keys_per_filter=150000 2>&1 | grep 'FP rate'
Predicted FP rate %: 0.422857
Average FP rate %: 0.379301
$
With more samples at 15 bits/key:
150K keys -> no warning; actual: 0.379% FP rate (baseline)
1M keys -> no warning; actual: 0.396% FP rate, 1.045x
9M keys -> no warning; actual: 0.563% FP rate, 1.485x
10M keys -> warning (1.5x); actual: 0.564% FP rate, 1.488x
15M keys -> warning (1.8x); actual: 0.668% FP rate, 1.76x
25M keys -> warning (2.4x); actual: 0.880% FP rate, 2.32x
At 10 bits/key:
150K keys -> no warning; actual: 1.17% FP rate (baseline)
1M keys -> no warning; actual: 1.16% FP rate
10M keys -> no warning; actual: 1.32% FP rate, 1.13x
25M keys -> no warning; actual: 1.63% FP rate, 1.39x
35M keys -> warning (1.6x); actual: 1.81% FP rate, 1.55x
At 5 bits/key:
150K keys -> no warning; actual: 9.32% FP rate (baseline)
25M keys -> no warning; actual: 9.62% FP rate, 1.03x
200M keys -> no warning; actual: 12.2% FP rate, 1.31x
250M keys -> warning (1.5x); actual: 12.8% FP rate, 1.37x
300M keys -> warning (1.6x); actual: 13.4% FP rate, 1.43x
The reason for the modest inaccuracy at low bits/key is that the assumption of independence between a collision between 32-hash values feeding the filter and an FP in the filter is not quite true for implementations using "simple" logic to compute indices from the stock hash result. There's math on this in my dissertation, but I don't think it's worth the effort just for these extreme cases (> 100 million keys and low-ish bits/key).
Differential Revision: D19471715
Pulled By: pdillinger
fbshipit-source-id: f80c96893a09bf1152630ff0b964e5cdd7e35c68
Summary:
Help users that would benefit most from new Bloom filter
implementation by logging a warning that recommends the using
format_version >= 5.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6312
Test Plan:
$ (for BPK in 10 13 14 19 20 50; do ./filter_bench -quick -impl=0 -bits_per_key=$BPK -m_queries=1 2>&1; done) | grep 'its/key'
Bits/key actual: 10.0647
Bits/key actual: 13.0593
[WARN] [/block_based/filter_policy.cc:546] Using legacy Bloom filter with high (14) bits/key. Significant filter space and/or accuracy improvement is available with format_verion>=5.
Bits/key actual: 14.0581
[WARN] [/block_based/filter_policy.cc:546] Using legacy Bloom filter with high (19) bits/key. Significant filter space and/or accuracy improvement is available with format_verion>=5.
Bits/key actual: 19.0542
[WARN] [/block_based/filter_policy.cc:546] Using legacy Bloom filter with high (20) bits/key. Dramatic filter space and/or accuracy improvement is available with format_verion>=5.
Bits/key actual: 20.0584
[WARN] [/block_based/filter_policy.cc:546] Using legacy Bloom filter with high (50) bits/key. Dramatic filter space and/or accuracy improvement is available with format_verion>=5.
Bits/key actual: 50.0577
Differential Revision: D19457191
Pulled By: pdillinger
fbshipit-source-id: 073d94cde5c70e03a160f953e1100c15ea83eda4
Summary:
Recent bug fix related to hash index introduced a new bug: hash index can return NotFound but it is not handled by BlockBasedTable::Get(). The end result is that Get() stops being executed too early. Fix it by ignoring NotFound code in Get().
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6305
Test Plan: A problematic DB used to return NotFound incorrectly, and now able to return correct result. Will try to construct a unit test too.0
Differential Revision: D19438925
fbshipit-source-id: e751afa8c13728d56511cfeb1bc811ecb99f3217
Summary:
Recent fix to Prefix Hash https://github.com/facebook/rocksdb/pull/6292 caused a bug that the newly created NotFound status in hash index is never reset. This causes reseek or implict reseek to return wrong results sometimes.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6302
Test Plan:
Add a unit test that would fail. Not fix.
crash test with hash test would fail in several seconds. With the fix, it will run about several minutes before failing with another failure.
Differential Revision: D19424572
fbshipit-source-id: c5276f36a95fd0e2837e30190476d2fe21ed8566
Summary:
When prefix is enabled the expected behavior when the prefix of the target does not exist is for Seek is to seek to any key larger than target and SeekToPrev to any key less than the target.
Currently. the prefix index (kHashSearch) returns OK status but sets Invalid() to indicate two cases: a prefix of the searched key does not exist, ii) the key is beyond the range of the keys in SST file. The SeekForPrev implementation in BlockBasedTable thus does not have enough information to know when it should set the index key to first (to return a key smaller than target). The patch fixes that by returning NotFound status for cases that the prefix does not exist. SeekForPrev in BlockBasedTable accordingly SeekToFirst instead of SeekToLast on the index iterator.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6297
Test Plan: SeekForPrev of non-exsiting prefix is added to block_test.cc, and a test case is added in db_test2, which fails without the fix.
Differential Revision: D19404695
fbshipit-source-id: cafbbf95f8f60ff9ede9ccc99d25bfa1cf6fcdc3
Summary:
kHashSearch index type is incompatible with index_block_restart_interval larger than 1. The patch asserts that and also resets index_block_restart_interval value if it is incompatible with kHashSearch.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6294
Differential Revision: D19394229
Pulled By: maysamyabandeh
fbshipit-source-id: 8a12712ab25e81094a7f71ecd43f773dd4fb6acd
Summary:
Right now BlockBasedTable::ApproximateSize() uses default setting about whether to use total order seek. There is no reason for that. There is no reason to do any filtering for approximate size boundary key, and it may introduce bugs. Disable it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6222
Test Plan: Run existing tests
Differential Revision: D19184787
fbshipit-source-id: 64180660bd2800914fff75104172b61c06f0b1c9
Summary:
This reverts commit 54f9092b0c.
It making our daily stress tests fail. Revert it until the issues are fixed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6220
Differential Revision: D19179881
Pulled By: maysamyabandeh
fbshipit-source-id: 99de0eaf776567fa81110b9ad2608234a16083ce
Summary:
Beside extending index_type to kHashSearch, it clarifies in the code base that this feature is incompatible with index_block_restart_interval > 1.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6210
Test Plan:
```
make -j32 crash_test
Differential Revision: D19166567
Pulled By: maysamyabandeh
fbshipit-source-id: 3aaf75a70a8b462d372d43aac69dbd10df303ec7
Summary:
Right now, sometimes file prefetching is still on when mmap is enabled. This causes bug of reading wrong data. In this commit, we remove all those possible paths.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6206
Test Plan: make crash_test with compaction_readahead_size, which used to fail. RUn all existing tests.
Differential Revision: D19149429
fbshipit-source-id: 9e18ea8c566e416aac9647bdd05afe596634791b
Summary:
buf_offset does not need to get the value from req.len for othe final block. It can cause test fail for clan_analyze. Remove it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6204
Test Plan: pass make asan_check
Differential Revision: D19145335
Pulled By: zhichao-cao
fbshipit-source-id: 8f6e74565746381b5c5ef598b97d746517b36e5b
Summary:
In the current MultiGet, if the KV-pairs do not belong to the data blocks in the block cache, multiple blocks are read from a SST. It will trigger one block read for each block request and read them in parallel. In some cases, if some data blocks are adjacent in the SST, the reads for these blocks can be combined to a single large read, which can reduce the system calls and reduce the read latency if possible.
Considering to fill the block cache, if multiple data blocks are in the same memory buffer, we need to copy them to the heap separately. Therefore, only in the case that 1) data block compression is enabled, and 2) compressed block cache is null, we can do combined read. Otherwise, extra memory copy is needed, which may cause extra overhead. In the current case, data blocks will be uncompressed to a new memory space.
Also, in the case that 1) data block compression is enabled, and 2) compressed block cache is null, it is possible the data block is actually not compressed. In the current logic, these data blocks will not be added to the uncompressed_cache. So if memory buffer is shared and the data block is not compressed, the data block are copied to the head and fill the cache.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6089
Test Plan: Added test case to ParallelIO.MultiGet. Pass make asan_check
Differential Revision: D18734668
Pulled By: zhichao-cao
fbshipit-source-id: 67c5615ed373e51e42635fd74b36f8f3a66d5da4
Summary:
The filter bits builder collects all the hashes to add in memory before adding them (because the number of keys is not known until we've walked over all the keys). Existing code uses a std::vector for this, which can mean up to 2x than necessary space allocated (and not freed) and up to ~2x write amplification in memory. Using std::deque uses close to minimal space (for large filters, the only time it matters), no write amplification, frees memory while building, and no need for large contiguous memory area. The only cost is more calls to allocator, which does not appear to matter, at least in benchmark test.
For now, this change only applies to the new (format_version=5) Bloom filter implementation, to ease before-and-after comparison downstream.
Temporary memory use during build is about the only way the new Bloom filter could regress vs. the old (because of upgrade to 64-bit hash) and that should only matter for full filters. This change should largely mitigate that potential regression.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6175
Test Plan:
Using filter_bench with -new_builder option and 6M keys per filter is like large full filter (improvement). 10k keys and no -new_builder is like partitioned filters (about the same). (Corresponding configurations run simultaneously on devserver.)
std::vector impl (before)
$ /usr/bin/time -v ./filter_bench -impl=2 -quick -new_builder -working_mem_size_mb=1000 -
average_keys_per_filter=6000000
Build avg ns/key: 52.2027
Maximum resident set size (kbytes): 1105016
$ /usr/bin/time -v ./filter_bench -impl=2 -quick -working_mem_size_mb=1000 -
average_keys_per_filter=10000
Build avg ns/key: 30.5694
Maximum resident set size (kbytes): 1208152
std::deque impl (after)
$ /usr/bin/time -v ./filter_bench -impl=2 -quick -new_builder -working_mem_size_mb=1000 -
average_keys_per_filter=6000000
Build avg ns/key: 39.0697
Maximum resident set size (kbytes): 1087196
$ /usr/bin/time -v ./filter_bench -impl=2 -quick -working_mem_size_mb=1000 -
average_keys_per_filter=10000
Build avg ns/key: 30.9348
Maximum resident set size (kbytes): 1207980
Differential Revision: D19053431
Pulled By: pdillinger
fbshipit-source-id: 2888e748723a19d9ea40403934f13cbb8483430c
Summary:
The current Env API encompasses both storage/file operations, as well as OS related operations. Most of the APIs return a Status, which does not have enough metadata about an error, such as whether its retry-able or not, scope (i.e fault domain) of the error etc., that may be required in order to properly handle a storage error. The file APIs also do not provide enough control over the IO SLA, such as timeout, prioritization, hinting about placement and redundancy etc.
This PR separates out the file/storage APIs from Env into a new FileSystem class. The APIs are updated to return an IOStatus with metadata about the error, as well as to take an IOOptions structure as input in order to allow more control over the IO.
The user can set both ```options.env``` and ```options.file_system``` to specify that RocksDB should use the former for OS related operations and the latter for storage operations. Internally, a ```CompositeEnvWrapper``` has been introduced that inherits from ```Env``` and redirects individual methods to either an ```Env``` implementation or the ```FileSystem``` as appropriate. When options are sanitized during ```DB::Open```, ```options.env``` is replaced with a newly allocated ```CompositeEnvWrapper``` instance if both env and file_system have been specified. This way, the rest of the RocksDB code can continue to function as before.
This PR also ports PosixEnv to the new API by splitting it into two - PosixEnv and PosixFileSystem. PosixEnv is defined as a sub-class of CompositeEnvWrapper, and threading/time functions are overridden with Posix specific implementations in order to avoid an extra level of indirection.
The ```CompositeEnvWrapper``` translates ```IOStatus``` return code to ```Status```, and sets the severity to ```kSoftError``` if the io_status is retryable. The error handling code in RocksDB can then recover the DB automatically.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5761
Differential Revision: D18868376
Pulled By: anand1976
fbshipit-source-id: 39efe18a162ea746fabac6360ff529baba48486f
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:
BlockBasedTableBuilder uses ExtractUserKey in EnterUnbuffered. This would
cause index filter building error, since user-provided timestamp is supported
by ExtractUserKeyAndStripTimestamp, and it's used in Add. This commit changes
ExtractUserKey to ExtractUserKeyAndStripTimestamp.
A test case is also added by modifying DBBasicTestWithTimestampWithParam_
PutAndGet test in db_basic_test to cover ExtractUserKeyAndStripTimestamp usage
in both kBuffered and kUnbuffered state of BlockBasedTableBuilder.
Before the ExtractUserKeyAndStripTimstamp fix:
```
$ ./db_basic_test --gtest_filter="*PutAndGet*"
Note: Google Test filter = *PutAndGet*
[==========] Running 2 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 2 tests from Timestamp/DBBasicTestWithTimestampWithParam
[ RUN ] Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/0
db/db_basic_test.cc:2109: Failure
db_->Get(ropts, cfh, "key" + std::to_string(j), &value)
NotFound:
db/db_basic_test.cc:2109: Failure
db_->Get(ropts, cfh, "key" + std::to_string(j), &value)
NotFound:
db/db_basic_test.cc:2109: Failure
db_->Get(ropts, cfh, "key" + std::to_string(j), &value)
NotFound:
db/db_basic_test.cc:2109: Failure
db_->Get(ropts, cfh, "key" + std::to_string(j), &value)
NotFound:
db/db_basic_test.cc:2109: Failure
db_->Get(ropts, cfh, "key" + std::to_string(j), &value)
NotFound:
[ FAILED ] Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/0, where GetParam() = false (1177 ms)
[ RUN ] Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/1
[ OK ] Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/1 (1056 ms)
[----------] 2 tests from Timestamp/DBBasicTestWithTimestampWithParam (2233 ms total)
[----------] Global test environment tear-down
[==========] 2 tests from 1 test case ran. (2233 ms total)
[ PASSED ] 1 test.
[ FAILED ] 1 test, listed below:
[ FAILED ] Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/0, where GetParam() = false
1 FAILED TEST
```
After the ExtractUserKeyAndStripTimstamp fix:
```
$ ./db_basic_test --gtest_filter="*PutAndGet*"
Note: Google Test filter = *PutAndGet*
[==========] Running 2 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 2 tests from Timestamp/DBBasicTestWithTimestampWithParam
[ RUN ] Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/0
[ OK ] Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/0 (1417 ms)
[ RUN ] Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/1
[ OK ] Timestamp/DBBasicTestWithTimestampWithParam.PutAndGet/1 (1041 ms)
[----------] 2 tests from Timestamp/DBBasicTestWithTimestampWithParam (2458 ms total)
[----------] Global test environment tear-down
[==========] 2 tests from 1 test case ran. (2458 ms total)
[ PASSED ] 2 tests.
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6100
Differential Revision: D18769654
Pulled By: riversand963
fbshipit-source-id: 76c2cf2c9a5e0d85db95d98e812e6af0c2a15c6b
Summary:
A longstanding bug in our C interface can trigger this
assertion; see issue https://github.com/facebook/rocksdb/issues/6129. Disabling the assertion for now
(for 6.6.0) and will re-enable on fix of that bug.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6128
Differential Revision: D18854899
Pulled By: pdillinger
fbshipit-source-id: 9eb5294b9f11b208dc1a8cc148aaa31e47ff892b
Summary:
This change enables custom implementations of FilterPolicy to
wrap a variety of NewBloomFilterPolicy and select among them based on
contextual information such as table level and compaction style.
* Moves FilterBuildingContext to public API and elaborates it with more
useful data. (It would be nice to put more general options-like data,
but at the time this object is constructed, we are using internal APIs
ImmutableCFOptions and MutableCFOptions and don't have easy access to
ColumnFamilyOptions that I can tell.)
* Renames BloomFilterPolicy::GetFilterBitsBuilderInternal to
GetBuilderWithContext, because it's now public.
* Plumbs through the table's "level_at_creation" for filter building
context.
* Simplified some tests by adding GetBuilder() to
MockBlockBasedTableTester.
* Adds test as DBBloomFilterTest.ContextCustomFilterPolicy, including
sample wrapper class LevelAndStyleCustomFilterPolicy.
* Fixes a cross-test bug in DBBloomFilterTest.OptimizeFiltersForHits
where it does not reset perf context.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6088
Test Plan: make check, valgrind on db_bloom_filter_test
Differential Revision: D18697817
Pulled By: pdillinger
fbshipit-source-id: 5f987a2d7b07cc7a33670bc08ca6b4ca698c1cf4
Summary:
There's no technological impediment to allowing the Bloom
filter bits/key to be non-integer (fractional/decimal) values, and it
provides finer control over the memory vs. accuracy trade-off. This is
especially handy in using the format_version=5 Bloom filter in place
of the old one, because bits_per_key=9.55 provides the same accuracy as
the old bits_per_key=10.
This change not only requires refining the logic for choosing the best
num_probes for a given bits/key setting, it revealed a flaw in that logic.
As bits/key gets higher, the best num_probes for a cache-local Bloom
filter is closer to bpk / 2 than to bpk * 0.69, the best choice for a
standard Bloom filter. For example, at 16 bits per key, the best
num_probes is 9 (FP rate = 0.0843%) not 11 (FP rate = 0.0884%).
This change fixes and refines that logic (for the format_version=5
Bloom filter only, just in case) based on empirical tests to find
accuracy inflection points between each num_probes.
Although bits_per_key is now specified as a double, the new Bloom
filter converts/rounds this to "millibits / key" for predictable/precise
internal computations. Just in case of unforeseen compatibility
issues, we round to the nearest whole number bits / key for the
legacy Bloom filter, so as not to unlock new behaviors for it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6092
Test Plan: unit tests included
Differential Revision: D18711313
Pulled By: pdillinger
fbshipit-source-id: 1aa73295f152a995328cb846ef9157ae8a05522a
Summary:
Adds an improved, replacement Bloom filter implementation (FastLocalBloom) for full and partitioned filters in the block-based table. This replacement is faster and more accurate, especially for high bits per key or millions of keys in a single filter.
Speed
The improved speed, at least on recent x86_64, comes from
* Using fastrange instead of modulo (%)
* Using our new hash function (XXH3 preview, added in a previous commit), which is much faster for large keys and only *slightly* slower on keys around 12 bytes if hashing the same size many thousands of times in a row.
* Optimizing the Bloom filter queries with AVX2 SIMD operations. (Added AVX2 to the USE_SSE=1 build.) Careful design was required to support (a) SIMD-optimized queries, (b) compatible non-SIMD code that's simple and efficient, (c) flexible choice of number of probes, and (d) essentially maximized accuracy for a cache-local Bloom filter. Probes are made eight at a time, so any number of probes up to 8 is the same speed, then up to 16, etc.
* Prefetching cache lines when building the filter. Although this optimization could be applied to the old structure as well, it seems to balance out the small added cost of accumulating 64 bit hashes for adding to the filter rather than 32 bit hashes.
Here's nominal speed data from filter_bench (200MB in filters, about 10k keys each, 10 bits filter data / key, 6 probes, avg key size 24 bytes, includes hashing time) on Skylake DE (relatively low clock speed):
$ ./filter_bench -quick -impl=2 -net_includes_hashing # New Bloom filter
Build avg ns/key: 47.7135
Mixed inside/outside queries...
Single filter net ns/op: 26.2825
Random filter net ns/op: 150.459
Average FP rate %: 0.954651
$ ./filter_bench -quick -impl=0 -net_includes_hashing # Old Bloom filter
Build avg ns/key: 47.2245
Mixed inside/outside queries...
Single filter net ns/op: 63.2978
Random filter net ns/op: 188.038
Average FP rate %: 1.13823
Similar build time but dramatically faster query times on hot data (63 ns to 26 ns), and somewhat faster on stale data (188 ns to 150 ns). Performance differences on batched and skewed query loads are between these extremes as expected.
The only other interesting thing about speed is "inside" (query key was added to filter) vs. "outside" (query key was not added to filter) query times. The non-SIMD implementations are substantially slower when most queries are "outside" vs. "inside". This goes against what one might expect or would have observed years ago, as "outside" queries only need about two probes on average, due to short-circuiting, while "inside" always have num_probes (say 6). The problem is probably the nastily unpredictable branch. The SIMD implementation has few branches (very predictable) and has pretty consistent running time regardless of query outcome.
Accuracy
The generally improved accuracy (re: Issue https://github.com/facebook/rocksdb/issues/5857) comes from a better design for probing indices
within a cache line (re: Issue https://github.com/facebook/rocksdb/issues/4120) and improved accuracy for millions of keys in a single filter from using a 64-bit hash function (XXH3p). Design details in code comments.
Accuracy data (generalizes, except old impl gets worse with millions of keys):
Memory bits per key: FP rate percent old impl -> FP rate percent new impl
6: 5.70953 -> 5.69888
8: 2.45766 -> 2.29709
10: 1.13977 -> 0.959254
12: 0.662498 -> 0.411593
16: 0.353023 -> 0.0873754
24: 0.261552 -> 0.0060971
50: 0.225453 -> ~0.00003 (less than 1 in a million queries are FP)
Fixes https://github.com/facebook/rocksdb/issues/5857
Fixes https://github.com/facebook/rocksdb/issues/4120
Unlike the old implementation, this implementation has a fixed cache line size (64 bytes). At 10 bits per key, the accuracy of this new implementation is very close to the old implementation with 128-byte cache line size. If there's sufficient demand, this implementation could be generalized.
Compatibility
Although old releases would see the new structure as corrupt filter data and read the table as if there's no filter, we've decided only to enable the new Bloom filter with new format_version=5. This provides a smooth path for automatic adoption over time, with an option for early opt-in.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6007
Test Plan: filter_bench has been used thoroughly to validate speed, accuracy, and correctness. Unit tests have been carefully updated to exercise new and old implementations, as well as the logic to select an implementation based on context (format_version).
Differential Revision: D18294749
Pulled By: pdillinger
fbshipit-source-id: d44c9db3696e4d0a17caaec47075b7755c262c5f
Summary:
Bug in PR https://github.com/facebook/rocksdb/issues/5941 when char is unsigned that should only affect
assertion on unused/invalid filter metadata.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6024
Test Plan: on ARM: ./bloom_test && ./db_bloom_filter_test && ./block_based_filter_block_test && ./full_filter_block_test && ./partitioned_filter_block_test
Differential Revision: D18461206
Pulled By: pdillinger
fbshipit-source-id: 68a7c813a0b5791c05265edc03cdf52c78880e9a
Summary:
The calculation in BlockBasedTable::MultiGet for the required buffer length for reading in compressed blocks is incorrect. It needs to take the 5-byte block trailer into account.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6014
Test Plan: Add a unit test DBBasicTest.MultiGetBufferOverrun that fails in asan_check before the fix, and passes after.
Differential Revision: D18412753
Pulled By: anand1976
fbshipit-source-id: 754dfb66be1d5f161a7efdf87be872198c7e3b72
Summary:
This PR fixes https://github.com/facebook/rocksdb/issues/5975. In ```BlockBasedTable::RetrieveMultipleBlocks()```, we were calling ```MaybeReadBlocksAndLoadToCache()```, which is a no-op if neither uncompressed nor compressed block cache are configured.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5991
Test Plan:
1. Add unit tests that fail with the old code and pass with the new
2. make check and asan_check
Cc spetrunia
Differential Revision: D18272744
Pulled By: anand1976
fbshipit-source-id: e62fa6090d1a6adf84fcd51dfd6859b03c6aebfe
Summary:
According to
https://github.com/facebook/rocksdb/wiki/Rocksdb-BlockBasedTable-Format,
the block read by BlockBasedTable::ReadMetaBlock is actually the meta index
block. Therefore, it is better to rename the function to ReadMetaIndexBlock.
This PR also applies some format change to existing code.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6009
Test Plan: make check
Differential Revision: D18333238
Pulled By: riversand963
fbshipit-source-id: 2c4340a29b3edba53d19c132cbfd04caf6242aed
Summary:
This change sets up for alternate implementations underlying
BloomFilterPolicy:
* Refactor BloomFilterPolicy and expose in internal .h file so that it's easy to iterate over / select implementations for testing, regardless of what the best public interface will look like. Most notably updated db_bloom_filter_test to use this.
* Hide FullFilterBitsBuilder from unit tests (alternate derived classes planned); expose the part important for testing (CalculateSpace), as abstract class BuiltinFilterBitsBuilder. (Also cleaned up internally exposed interface to CalculateSpace.)
* Rename BloomTest -> BlockBasedBloomTest for clarity (despite ongoing confusion between block-based table and block-based filter)
* Assert that block-based filter construction interface is only used on BloomFilterPolicy appropriately constructed. (A couple of tests updated to add ", true".)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5967
Test Plan: make check
Differential Revision: D18138704
Pulled By: pdillinger
fbshipit-source-id: 55ef9273423b0696309e251f50b8c1b5e9ec7597
Summary:
Some filtering tests were unfriendly to new implementations of
FilterBitsBuilder because of dynamic_cast to FullFilterBitsBuilder. Most
of those have now been cleaned up, worked around, or at least changed
from crash on dynamic_cast failure to individual test failure.
Also put some clarifying comments on filter-related APIs.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5960
Test Plan: make check
Differential Revision: D18121223
Pulled By: pdillinger
fbshipit-source-id: e83827d9d5d96315d96f8e25a99cd70f497d802c
Summary:
- Updated our included xxhash implementation to version 0.7.2 (== the latest dev version as of 2019-10-09).
- Using XXH_NAMESPACE (like other fb projects) to avoid potential name collisions.
- Added fastrange64, and unit tests for it and fastrange32. These are faster alternatives to hash % range.
- Use preview version of XXH3 instead of MurmurHash64A for NPHash64
-- Had to update cache_test to increase probability of passing for any given hash function.
- Use fastrange64 instead of % with uses of NPHash64
-- Had to fix WritePreparedTransactionTest.CommitOfDelayedPrepared to avoid deadlock apparently caused by new hash collision.
- Set default seed for NPHash64 because specifying a seed rarely makes sense for it.
- Removed unnecessary include xxhash.h in a popular .h file
- Rename preview version of XXH3 to XXH3p for clarity and to ease backward compatibility in case final version of XXH3 is integrated.
Relying on existing unit tests for NPHash64-related changes. Each new implementation of fastrange64 passed unit tests when manipulating my local build to select it. I haven't done any integration performance tests, but I consider the improved performance of the pieces being swapped in to be well established.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5909
Differential Revision: D18125196
Pulled By: pdillinger
fbshipit-source-id: f6bf83d49d20cbb2549926adf454fd035f0ecc0d
Summary:
The parts that are used to implement FilterPolicy /
NewBloomFilterPolicy and not used other than for the block-based table
should be consolidated under table/block_based/filter_policy*.
This change is step 2 of 2:
mv util/bloom.cc table/block_based/filter_policy.cc
This gets its own PR so that git has the best chance of following the
rename for blame purposes. Note that low-level shared implementation
details of Bloom filters remain in util/bloom_impl.h, and
util/bloom_test.cc remains where it is for now.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5966
Test Plan: make check
Differential Revision: D18124930
Pulled By: pdillinger
fbshipit-source-id: 823bc09025b3395f092ef46a46aa5ba92a914d84
Summary:
The parts that are used to implement FilterPolicy /
NewBloomFilterPolicy and not used other than for the block-based table
should be consolidated under table/block_based/filter_policy*. I don't
foresee sharing these APIs with e.g. the Plain Table because they don't
expose hashes for reuse in indexing.
This change is step 1 of 2:
(a) mv table/full_filter_bits_builder.h to
table/block_based/filter_policy_internal.h which I expect to expand
soon to internally reveal more implementation details for testing.
(b) consolidate eventual contents of table/block_based/filter_policy.cc
in util/bloom.cc, which has the most elaborate revision history
(see step 2 ...)
Step 2 soon to follow:
mv util/bloom.cc table/block_based/filter_policy.cc
This gets its own PR so that git has the best chance of following the
rename for blame purposes. Note that low-level shared implementation
details of Bloom filters are in util/bloom_impl.h.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5963
Test Plan: make check
Differential Revision: D18121199
Pulled By: pdillinger
fbshipit-source-id: 8f21732c3d8909777e3240e4ac3123d73140326a
Summary:
A recent change introduced readahead inside VerifyChecksum(). However it is not compatible with mmap mode and generated wrong checksum verification failure. Fix it by not enabling readahead in mmap
mode.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5945
Test Plan: Add a unit test that used to fail.
Differential Revision: D18021443
fbshipit-source-id: 6f2eb600f81b26edb02222563a4006869d576bff
Summary:
Amongst other things, PR https://github.com/facebook/rocksdb/issues/5504 refactored the filter block readers so that
only the filter block contents are stored in the block cache (as opposed to the
earlier design where the cache stored the filter block reader itself, leading to
potentially dangling pointers and concurrency bugs). However, this change
introduced a performance hit since with the new code, the metadata fields are
re-parsed upon every access. This patch reunites the block contents with the
filter bits reader to eliminate this overhead; since this is still a self-contained
pure data object, it is safe to store it in the cache. (Note: this is similar to how
the zstd digest is handled.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5936
Test Plan:
make asan_check
filter_bench results for the old code:
```
$ ./filter_bench -quick
WARNING: Assertions are enabled; benchmarks unnecessarily slow
Building...
Build avg ns/key: 26.7153
Number of filters: 16669
Total memory (MB): 200.009
Bits/key actual: 10.0647
----------------------------
Inside queries...
Dry run (46b) ns/op: 33.4258
Single filter ns/op: 42.5974
Random filter ns/op: 217.861
----------------------------
Outside queries...
Dry run (25d) ns/op: 32.4217
Single filter ns/op: 50.9855
Random filter ns/op: 219.167
Average FP rate %: 1.13993
----------------------------
Done. (For more info, run with -legend or -help.)
$ ./filter_bench -quick -use_full_block_reader
WARNING: Assertions are enabled; benchmarks unnecessarily slow
Building...
Build avg ns/key: 26.5172
Number of filters: 16669
Total memory (MB): 200.009
Bits/key actual: 10.0647
----------------------------
Inside queries...
Dry run (46b) ns/op: 32.3556
Single filter ns/op: 83.2239
Random filter ns/op: 370.676
----------------------------
Outside queries...
Dry run (25d) ns/op: 32.2265
Single filter ns/op: 93.5651
Random filter ns/op: 408.393
Average FP rate %: 1.13993
----------------------------
Done. (For more info, run with -legend or -help.)
```
With the new code:
```
$ ./filter_bench -quick
WARNING: Assertions are enabled; benchmarks unnecessarily slow
Building...
Build avg ns/key: 25.4285
Number of filters: 16669
Total memory (MB): 200.009
Bits/key actual: 10.0647
----------------------------
Inside queries...
Dry run (46b) ns/op: 31.0594
Single filter ns/op: 43.8974
Random filter ns/op: 226.075
----------------------------
Outside queries...
Dry run (25d) ns/op: 31.0295
Single filter ns/op: 50.3824
Random filter ns/op: 226.805
Average FP rate %: 1.13993
----------------------------
Done. (For more info, run with -legend or -help.)
$ ./filter_bench -quick -use_full_block_reader
WARNING: Assertions are enabled; benchmarks unnecessarily slow
Building...
Build avg ns/key: 26.5308
Number of filters: 16669
Total memory (MB): 200.009
Bits/key actual: 10.0647
----------------------------
Inside queries...
Dry run (46b) ns/op: 33.2968
Single filter ns/op: 58.6163
Random filter ns/op: 291.434
----------------------------
Outside queries...
Dry run (25d) ns/op: 32.1839
Single filter ns/op: 66.9039
Random filter ns/op: 292.828
Average FP rate %: 1.13993
----------------------------
Done. (For more info, run with -legend or -help.)
```
Differential Revision: D17991712
Pulled By: ltamasi
fbshipit-source-id: 7ea205550217bfaaa1d5158ebd658e5832e60f29
Summary:
Partition Filters make use of a top-level index to find the partition that might have the bloom hash of the key. The index is with internal key format (before format version 3). Each partition contains the i) blooms of the keys in that range ii) bloom of prefixes of keys in that range, iii) the bloom of the prefix of the last key in the previous partition.
When ::SeekForPrev(key), we first perform a prefix bloom test on the SST file. The partition however is identified using the full internal key, rather than the prefix key. The reason is to be compatible with the internal key format of the top-level index. This creates a corner case. Example:
- SST k, Partition N: P1K1, P1K2
- SST k, top-level index: P1K2
- SST k+1, Partition 1: P2K1, P3K1
- SST k+1 top-level index: P3K1
When SeekForPrev(P1K3), it should point us to P1K2. However SST k top-level index would reject P1K3 since it is out of range.
One possible fix would be to search with the prefix P1 (instead of full internal key P1K3) however the details of properly comparing prefix with full internal key might get complicated. The fix we apply in this PR is to look into the last partition anyway even if the key is out of range.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5907
Differential Revision: D17889918
Pulled By: maysamyabandeh
fbshipit-source-id: 169fd7b3c71dbc08808eae5a8340611ebe5bdc1e
Summary:
Since we do not evict a file's blocks from block cache before that file
is deleted, we require a file's cache ID prefix is both unique and
non-reusable. However, the Windows functionality we were relying on only
guaranteed uniqueness. That meant a newly created file could be assigned
the same cache ID prefix as a deleted file. If the newly created file
had block offsets matching the deleted file, full cache keys could be
exactly the same, resulting in obsolete data blocks returned from cache
when trying to read from the new file.
We noticed this when running on FAT32 where compaction was writing out
of order keys due to reading obsolete blocks from its input files. The
functionality is documented as behaving the same on NTFS, although I
wasn't able to repro it there.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5844
Test Plan:
we had a reliable repro of out-of-order keys on FAT32 that
was fixed by this change
Differential Revision: D17752442
fbshipit-source-id: 95d983f9196cf415f269e19293b97341edbf7e00
Summary:
Example: using the tool before and after PR https://github.com/facebook/rocksdb/issues/5784 shows that
the refactoring, presumed performance-neutral, actually sped up SST
filters by about 3% to 8% (repeatable result):
Before:
- Dry run ns/op: 22.4725
- Single filter ns/op: 51.1078
- Random filter ns/op: 120.133
After:
+ Dry run ns/op: 22.2301
+ Single filter run ns/op: 47.4313
+ Random filter ns/op: 115.9
Only tests filters for the block-based table (full filters and
partitioned filters - same implementation; not block-based filters),
which seems to be the recommended format/implementation.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5825
Differential Revision: D17804987
Pulled By: pdillinger
fbshipit-source-id: 0f18a9c254c57f7866030d03e7fa4ba503bac3c5
Summary:
When an iterator reseek happens with the user specifying a new iterate_upper_bound in ReadOptions, and the new seek position is at the end of the same data block, the Seek() ends up using a stale value of data_block_within_upper_bound_ and may return incorrect results.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5883
Test Plan: Added a new test case DBIteratorTest.IterReseekNewUpperBound. Verified that it failed due to the assertion failure without the fix, and passes with the fix.
Differential Revision: D17752740
Pulled By: anand1976
fbshipit-source-id: f9b635ff5d6aeb0e1bef102cf8b2f900efd378e3
Summary:
Without this fix, compiler complains.
```
$ROCKSDB_NO_FBCODE=1 USE_CLANG=1 make ldb
table/block_based/full_filter_block.cc: In constructor ‘rocksdb::FullFilterBlockBuilder::FullFilterBlockBuilder(const rocksdb::SliceTransform*, bool, rocksdb::FilterBitsBuilder*)’:
table/block_based/full_filter_block.cc:20:43: error: declaration of ‘prefix_extractor’ shadows a member of 'this' [-Werror=shadow]
FilterBitsBuilder* filter_bits_builder)
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5872
Test Plan:
```
$ROCKSDB_NO_FBCODE=1 make all
```
Differential Revision: D17690058
Pulled By: riversand963
fbshipit-source-id: 19e3d9bd86e1123847095240e73d30da5d66240e
Summary:
This reverts commit 9fad3e21eb.
Iterator verification in stress tests sometimes fail for assertion
table/block_based/block_based_table_reader.cc:2973: void rocksdb::BlockBasedTableIterator<TBlockIter, TValue>::FindBlockForward() [with TBlockIter = rocksdb::DataBlockIter; TValue = rocksdb::Slice]: Assertion `!next_block_is_out_of_bound || user_comparator_.Compare(*read_options_.iterate_upper_bound, index_iter_->user_key()) <= 0' failed.
It is likely to be linked to https://github.com/facebook/rocksdb/pull/5286 together with https://github.com/facebook/rocksdb/pull/5468 as the former PR makes some child iterator's seek being avoided, so that upper bound condition fails to be updated there. Strictly speaking, the former PR was merged before the latter one, but the latter one feels a more important improvement so I choose to revert the former one for now.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5871
Differential Revision: D17689196
fbshipit-source-id: 4ded5be68f67bee2782d31a29cb72ea68f59dd8c
Summary:
Partitioned filters make use of a top-level index to find the partition in which the filter resides. The top-level index has a key per partition. The key is guaranteed to be larger or equal than any key in that partition. When used with format_version 3, which excludes the sequence number form index keys, the separator key in the index could be equal to the prefix of the keys in the next partition. In this way, when searching for the key, the top-level index will lead us to the previous partition, which has no key with that prefix. The prefix bloom test thus returns false, although the prefix exists in the bloom of the next partition.
The patch fixes that by a hack: It always adds the prefix of the first key of the next partition to the bloom of the current partition. In this way, in the corner cases that the index will lead us to the previous partition, we still can find the bloom filter there.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5835
Differential Revision: D17513585
Pulled By: maysamyabandeh
fbshipit-source-id: e2d1ff26c759e6e03875c4d57f4228316ecf50e9
Summary:
Further apply formatter to more recent commits.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5830
Test Plan: Run all existing tests.
Differential Revision: D17488031
fbshipit-source-id: 137458fd94d56dd271b8b40c522b03036943a2ab
Summary:
For our default block cache, each additional entry has extra memory overhead. It include LRUHandle (72 bytes currently) and the cache key (two varint64, file id and offset). The usage is not negligible. For example for block_size=4k, the overhead accounts for an extra 2% memory usage for the cache. The patch charging the cache for the extra usage, reducing untracked memory usage outside block cache. The feature is enabled by default and can be disabled by passing kDontChargeCacheMetadata to the cache constructor.
This PR builds up on https://github.com/facebook/rocksdb/issues/4258
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5797
Test Plan:
- Existing tests are updated to either disable the feature when the test has too much dependency on the old way of accounting the usage or increasing the cache capacity to account for the additional charge of metadata.
- The Usage tests in cache_test.cc are augmented to test the cache usage under kFullChargeCacheMetadata.
Differential Revision: D17396833
Pulled By: maysamyabandeh
fbshipit-source-id: 7684ccb9f8a40ca595e4f5efcdb03623afea0c6f
Summary:
file_reader_writer.h and .cc contain several files and helper function, and it's hard to navigate. Separate it to multiple files and put them under file/
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5803
Test Plan: Build whole project using make and cmake.
Differential Revision: D17374550
fbshipit-source-id: 10efca907721e7a78ed25bbf74dc5410dea05987
Summary:
Use delete to disable automatic generated methods instead of private, and put the constructor together for more clear.This modification cause the unused field warning, so add unused attribute to disable this warning.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5009
Differential Revision: D17288733
fbshipit-source-id: 8a767ce096f185f1db01bd28fc88fef1cdd921f3
Summary:
PR https://github.com/facebook/rocksdb/issues/5584 decoupled the uncompression dictionary object from the underlying block data; however, this defeats the purpose of the digested ZSTD dictionary, since the whole point
of the digest is to create it once and reuse it over and over again. This patch goes back to
storing the uncompression dictionary itself in the cache (which should be now safe to do,
since it no longer includes a Statistics pointer), while preserving the rest of the refactoring.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5645
Test Plan: make asan_check
Differential Revision: D16551864
Pulled By: ltamasi
fbshipit-source-id: 2a7e2d34bb16e70e3c816506d5afe1d842057800
Summary:
To improve code readability, since RetrieveBlock already calls MaybeReadBlockAndLoadToCache, we avoid name similarity of the functions that call RetrieveBlock with MaybeReadBlockAndLoadToCache. The patch thus renames MaybeLoadBlocksToCache to RetrieveMultipleBlock and deletes GetDataBlockFromCache, which contains only two lines.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5726
Differential Revision: D16962535
Pulled By: maysamyabandeh
fbshipit-source-id: 99e8946808ce4eb7857592b9003812e3004f92d6
Summary:
The batched MultiGet() implementation was not correctly handling bloom filter lookups when whole_key_filtering is disabled. It was incorrectly skipping keys not in the prefix_extractor domain, and not calling transform for keys in domain. This PR fixes both problems by moving the domain check and transformation to the FilterBlockReader.
Tests:
Unit test (confirmed failed before the fix)
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5665
Differential Revision: D16902380
Pulled By: anand1976
fbshipit-source-id: a6be81ad68a6e37134a65246aec7a2c590eccf00
Summary:
Right now VerifyChecksum() doesn't do read-ahead. In some use cases, users won't be able to achieve good performance. With this change, by default, RocksDB will do a default readahead, and users will be able to overwrite the readahead size by passing in a ReadOptions.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5713
Test Plan: Add a new unit test.
Differential Revision: D16860874
fbshipit-source-id: 0cff0fe79ac855d3d068e6ccd770770854a68413
Peter Dillinger