Basic MultiGet support for partitioned filters (#6757)
Summary: In MultiGet, access each applicable filter partition only once per batch, rather than for each applicable key. Also, * Fix Bloom stats for MultiGet * Fix/refactor MultiGetContext::Range::KeysLeft, including * Add efficient BitsSetToOne implementation * Assert that MultiGetContext::Range does not go beyond shift range Performance test: Generate db: $ ./db_bench --benchmarks=fillrandom --num=15000000 --cache_index_and_filter_blocks -bloom_bits=10 -partition_index_and_filters=true ... Before (middle performing run of three; note some missing Bloom stats): $ ./db_bench --use-existing-db --benchmarks=multireadrandom --num=15000000 --cache_index_and_filter_blocks --bloom_bits=10 --threads=16 --cache_size=20000000 -partition_index_and_filters -batch_size=32 -multiread_batched -statistics --duration=20 2>&1 | egrep 'micros/op|block.cache.filter.hit|bloom.filter.(full|use)|number.multiget' multireadrandom : 26.403 micros/op 597517 ops/sec; (548427 of 671968 found) rocksdb.block.cache.filter.hit COUNT : 83443275 rocksdb.bloom.filter.useful COUNT : 0 rocksdb.bloom.filter.full.positive COUNT : 0 rocksdb.bloom.filter.full.true.positive COUNT : 7931450 rocksdb.number.multiget.get COUNT : 385984 rocksdb.number.multiget.keys.read COUNT : 12351488 rocksdb.number.multiget.bytes.read COUNT : 793145000 rocksdb.number.multiget.keys.found COUNT : 7931450 After (middle performing run of three): $ ./db_bench_new --use-existing-db --benchmarks=multireadrandom --num=15000000 --cache_index_and_filter_blocks --bloom_bits=10 --threads=16 --cache_size=20000000 -partition_index_and_filters -batch_size=32 -multiread_batched -statistics --duration=20 2>&1 | egrep 'micros/op|block.cache.filter.hit|bloom.filter.(full|use)|number.multiget' multireadrandom : 21.024 micros/op 752963 ops/sec; (705188 of 863968 found) rocksdb.block.cache.filter.hit COUNT : 49856682 rocksdb.bloom.filter.useful COUNT : 45684579 rocksdb.bloom.filter.full.positive COUNT : 10395458 rocksdb.bloom.filter.full.true.positive COUNT : 9908456 rocksdb.number.multiget.get COUNT : 481984 rocksdb.number.multiget.keys.read COUNT : 15423488 rocksdb.number.multiget.bytes.read COUNT : 990845600 rocksdb.number.multiget.keys.found COUNT : 9908456 So that's about 25% higher throughput even for random keys Pull Request resolved: https://github.com/facebook/rocksdb/pull/6757 Test Plan: unit test included Reviewed By: anand1976 Differential Revision: D21243256 Pulled By: pdillinger fbshipit-source-id: 5644a1468d9e8c8575be02f4e04bc5d62dbbb57f
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util/math.h
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