rocksdb/table/block_based
Peter Dillinger 60af964372 Experimental (production candidate) SST schema for Ribbon filter (#7658)
Summary:
Added experimental public API for Ribbon filter:
NewExperimentalRibbonFilterPolicy(). This experimental API will
take a "Bloom equivalent" bits per key, and configure the Ribbon
filter for the same FP rate as Bloom would have but ~30% space
savings. (Note: optimize_filters_for_memory is not yet implemented
for Ribbon filter. That can be added with no effect on schema.)

Internally, the Ribbon filter is configured using a "one_in_fp_rate"
value, which is 1 over desired FP rate. For example, use 100 for 1%
FP rate. I'm expecting this will be used in the future for configuring
Bloom-like filters, as I expect people to more commonly hold constant
the filter accuracy and change the space vs. time trade-off, rather than
hold constant the space (per key) and change the accuracy vs. time
trade-off, though we might make that available.

### Benchmarking

```
$ ./filter_bench -impl=2 -quick -m_keys_total_max=200 -average_keys_per_filter=100000 -net_includes_hashing
Building...
Build avg ns/key: 34.1341
Number of filters: 1993
Total size (MB): 238.488
Reported total allocated memory (MB): 262.875
Reported internal fragmentation: 10.2255%
Bits/key stored: 10.0029
----------------------------
Mixed inside/outside queries...
  Single filter net ns/op: 18.7508
  Random filter net ns/op: 258.246
    Average FP rate %: 0.968672
----------------------------
Done. (For more info, run with -legend or -help.)
$ ./filter_bench -impl=3 -quick -m_keys_total_max=200 -average_keys_per_filter=100000 -net_includes_hashing
Building...
Build avg ns/key: 130.851
Number of filters: 1993
Total size (MB): 168.166
Reported total allocated memory (MB): 183.211
Reported internal fragmentation: 8.94626%
Bits/key stored: 7.05341
----------------------------
Mixed inside/outside queries...
  Single filter net ns/op: 58.4523
  Random filter net ns/op: 363.717
    Average FP rate %: 0.952978
----------------------------
Done. (For more info, run with -legend or -help.)
```

168.166 / 238.488 = 0.705  -> 29.5% space reduction

130.851 / 34.1341 = 3.83x construction time for this Ribbon filter vs. lastest Bloom filter (could make that as little as about 2.5x for less space reduction)

### Working around a hashing "flaw"

bloom_test discovered a flaw in the simple hashing applied in
StandardHasher when num_starts == 1 (num_slots == 128), showing an
excessively high FP rate.  The problem is that when many entries, on the
order of number of hash bits or kCoeffBits, are associated with the same
start location, the correlation between the CoeffRow and ResultRow (for
efficiency) can lead to a solution that is "universal," or nearly so, for
entries mapping to that start location. (Normally, variance in start
location breaks the effective association between CoeffRow and
ResultRow; the same value for CoeffRow is effectively different if start
locations are different.) Without kUseSmash and with num_starts > 1 (thus
num_starts ~= num_slots), this flaw should be completely irrelevant.  Even
with 10M slots, the chances of a single slot having just 16 (or more)
entries map to it--not enough to cause an FP problem, which would be local
to that slot if it happened--is 1 in millions. This spreadsheet formula
shows that: =1/(10000000*(1 - POISSON(15, 1, TRUE)))

As kUseSmash==false (the setting for Standard128RibbonBitsBuilder) is
intended for CPU efficiency of filters with many more entries/slots than
kCoeffBits, a very reasonable work-around is to disallow num_starts==1
when !kUseSmash, by making the minimum non-zero number of slots
2*kCoeffBits. This is the work-around I've applied. This also means that
the new Ribbon filter schema (Standard128RibbonBitsBuilder) is not
space-efficient for less than a few hundred entries. Because of this, I
have made it fall back on constructing a Bloom filter, under existing
schema, when that is more space efficient for small filters. (We can
change this in the future if we want.)

TODO: better unit tests for this case in ribbon_test, and probably
update StandardHasher for kUseSmash case so that it can scale nicely to
small filters.

### Other related changes

* Add Ribbon filter to stress/crash test
* Add Ribbon filter to filter_bench as -impl=3
* Add option string support, as in "filter_policy=experimental_ribbon:5.678;"
where 5.678 is the Bloom equivalent bits per key.
* Rename internal mode BloomFilterPolicy::kAuto to kAutoBloom
* Add a general BuiltinFilterBitsBuilder::CalculateNumEntry based on
binary searching CalculateSpace (inefficient), so that subclasses
(especially experimental ones) don't have to provide an efficient
implementation inverting CalculateSpace.
* Minor refactor FastLocalBloomBitsBuilder for new base class
XXH3pFilterBitsBuilder shared with new Standard128RibbonBitsBuilder,
which allows the latter to fall back on Bloom construction in some
extreme cases.
* Mostly updated bloom_test for Ribbon filter, though a test like
FullBloomTest::Schema is a next TODO to ensure schema stability
(in case this becomes production-ready schema as it is).
* Add some APIs to ribbon_impl.h for configuring Ribbon filters.
Although these are reasonably covered by bloom_test, TODO more unit
tests in ribbon_test
* Added a "tool" FindOccupancyForSuccessRate to ribbon_test to get data
for constructing the linear approximations in GetNumSlotsFor95PctSuccess.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7658

Test Plan:
Some unit tests updated but other testing is left TODO. This
is considered experimental but laying down schema compatibility as early
as possible in case it proves production-quality. Also tested in
stress/crash test.

Reviewed By: jay-zhuang

Differential Revision: D24899349

Pulled By: pdillinger

fbshipit-source-id: 9715f3e6371c959d923aea8077c9423c7a9f82b8
2020-11-12 20:46:14 -08:00
..
binary_search_index_reader.cc Separate internal and user key comparators in BlockIter (#6944) 2020-07-07 17:26:16 -07:00
binary_search_index_reader.h Extend Get/MultiGet deadline support to table open (#6982) 2020-06-29 14:53:17 -07:00
block_based_filter_block_test.cc Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
block_based_filter_block.cc Extend Get/MultiGet deadline support to table open (#6982) 2020-06-29 14:53:17 -07:00
block_based_filter_block.h Extend Get/MultiGet deadline support to table open (#6982) 2020-06-29 14:53:17 -07:00
block_based_table_builder.cc Remove unused includes (#7604) 2020-10-28 23:22:27 -07:00
block_based_table_builder.h Make parallel compression optimization code tidier (#6888) 2020-10-22 11:05:25 -07:00
block_based_table_factory.cc fix read_amp_bytes_per_bit field size (#7651) 2020-11-10 11:14:48 -08:00
block_based_table_factory.h Create a Customizable class to load classes and configurations (#6590) 2020-11-11 15:10:41 -08:00
block_based_table_iterator.cc Clean up InternalIterator upper bound logic a little bit (#7200) 2020-08-05 10:44:57 -07:00
block_based_table_iterator.h Clean up InternalIterator upper bound logic a little bit (#7200) 2020-08-05 10:44:57 -07:00
block_based_table_reader_impl.h Divide block_based_table_reader.cc (#6527) 2020-03-12 21:41:50 -07:00
block_based_table_reader_test.cc Fix many tests to run with MEM_ENV and ENCRYPTED_ENV; Introduce a MemoryFileSystem class (#7566) 2020-10-27 10:33:09 -07:00
block_based_table_reader.cc Fix MultiGet unable to query timestamp data issue (#7589) 2020-11-03 09:45:41 -08:00
block_based_table_reader.h Add sst_file_dumper status check (#7315) 2020-09-04 19:26:42 -07:00
block_builder.cc Add pipelined & parallel compression optimization (#6262) 2020-04-01 16:40:18 -07:00
block_builder.h Add pipelined & parallel compression optimization (#6262) 2020-04-01 16:40:18 -07:00
block_prefetcher.cc Add buffer prefetch support for non directIO usecase (#7312) 2020-08-27 18:16:53 -07:00
block_prefetcher.h De-template block based table iterator (#6531) 2020-03-16 12:20:50 -07:00
block_prefix_index.cc Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
block_prefix_index.h Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
block_test.cc More Makefile Cleanup (#7097) 2020-07-09 14:35:17 -07:00
block_type.h Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
block.cc Remove unused includes (#7604) 2020-10-28 23:22:27 -07:00
block.h Add EnvTestWithParam::OptionsTest to the ASSERT_STATUS_CHECKED passes (#7283) 2020-08-20 19:18:35 -07:00
cachable_entry.h Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
data_block_footer.cc Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
data_block_footer.h Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
data_block_hash_index_test.cc More Makefile Cleanup (#7097) 2020-07-09 14:35:17 -07:00
data_block_hash_index.cc Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
data_block_hash_index.h Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
filter_block_reader_common.cc Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
filter_block_reader_common.h Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
filter_block.h Fix MultiGet unable to query timestamp data issue (#7589) 2020-11-03 09:45:41 -08:00
filter_policy_internal.h Experimental (production candidate) SST schema for Ribbon filter (#7658) 2020-11-12 20:46:14 -08:00
filter_policy.cc Experimental (production candidate) SST schema for Ribbon filter (#7658) 2020-11-12 20:46:14 -08:00
flush_block_policy.cc Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
flush_block_policy.h Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
full_filter_block_test.cc Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
full_filter_block.cc Fix MultiGet unable to query timestamp data issue (#7589) 2020-11-03 09:45:41 -08:00
full_filter_block.h Extend Get/MultiGet deadline support to table open (#6982) 2020-06-29 14:53:17 -07:00
hash_index_reader.cc Separate internal and user key comparators in BlockIter (#6944) 2020-07-07 17:26:16 -07:00
hash_index_reader.h Extend Get/MultiGet deadline support to table open (#6982) 2020-06-29 14:53:17 -07:00
index_builder.cc Move break into block (#7468) 2020-09-30 20:24:23 -07:00
index_builder.h Make db_basic_test pass assert status checked (#7452) 2020-09-29 09:49:04 -07:00
index_reader_common.cc Divide block_based_table_reader.cc (#6527) 2020-03-12 21:41:50 -07:00
index_reader_common.h Divide block_based_table_reader.cc (#6527) 2020-03-12 21:41:50 -07:00
mock_block_based_table.h For ApproximateSizes, pro-rate table metadata size over data blocks (#6784) 2020-06-02 12:30:23 -07:00
parsed_full_filter_block.cc Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
parsed_full_filter_block.h Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433) 2020-02-20 12:09:57 -08:00
partitioned_filter_block_test.cc Remove unused includes (#7604) 2020-10-28 23:22:27 -07:00
partitioned_filter_block.cc Return error if Get/Multi() fails in Prefetching Filter blocks (#7543) 2020-10-14 10:45:36 -07:00
partitioned_filter_block.h Return error if Get/Multi() fails in Prefetching Filter blocks (#7543) 2020-10-14 10:45:36 -07:00
partitioned_index_iterator.cc Fix misspelling of PartitionedIndexIterator (#7450) 2020-09-29 16:28:13 -07:00
partitioned_index_iterator.h Fix misspelling of PartitionedIndexIterator (#7450) 2020-09-29 16:28:13 -07:00
partitioned_index_reader.cc Redesign block cache pinning API (#7520) 2020-10-11 14:58:24 -07:00
partitioned_index_reader.h Get() to fail with underlying failures in PartitionIndexReader::CacheDependencies() (#7297) 2020-08-25 19:01:05 -07:00
reader_common.cc Fix block checksum for >=4GB, refactor (#6978) 2020-06-19 16:18:24 -07:00
reader_common.h Bring the Configurable options together (#5753) 2020-09-14 17:01:01 -07:00
uncompression_dict_reader.cc Extend Get/MultiGet deadline support to table open (#6982) 2020-06-29 14:53:17 -07:00
uncompression_dict_reader.h Extend Get/MultiGet deadline support to table open (#6982) 2020-06-29 14:53:17 -07:00