68a9c186d0
Summary: * Inefficient block-based filter is no longer customizable in the public API, though (for now) can still be enabled. * Removed deprecated FilterPolicy::CreateFilter() and FilterPolicy::KeyMayMatch() * Removed `rocksdb_filterpolicy_create()` from C API * Change meaning of nullptr return from GetBuilderWithContext() from "use block-based filter" to "generate no filter in this case." This is a cleaner solution to the proposal in https://github.com/facebook/rocksdb/issues/8250. * Also, when user specifies bits_per_key < 0.5, we now round this down to "no filter" because we expect a filter with >= 80% FP rate is unlikely to be worth the CPU cost of accessing it (esp with cache_index_and_filter_blocks=1 or partition_filters=1). * bits_per_key >= 0.5 and < 1.0 is still rounded up to 1.0 (for 62% FP rate) * This also gives us some support for configuring filters from OPTIONS file as currently saved: `filter_policy=rocksdb.BuiltinBloomFilter`. Opening from such an options file will enable reading filters (an improvement) but not writing new ones. (See Customizable follow-up below.) * Also removed deprecated functions * FilterBitsBuilder::CalculateNumEntry() * FilterPolicy::GetFilterBitsBuilder() * NewExperimentalRibbonFilterPolicy() * Remove default implementations of * FilterBitsBuilder::EstimateEntriesAdded() * FilterBitsBuilder::ApproximateNumEntries() * FilterPolicy::GetBuilderWithContext() * Remove support for "filter_policy=experimental_ribbon" configuration string. * Allow "filter_policy=bloomfilter:n" without bool to discourage use of block-based filter. Some pieces for https://github.com/facebook/rocksdb/issues/9389 Likely follow-up (later PRs): * Refactoring toward FilterPolicy Customizable, so that we can generate filters with same configuration as before when configuring from options file. * Remove support for user enabling block-based filter (ignore `bool use_block_based_builder`) * Some months after this change, we could even remove read support for block-based filter, because it is not critical to DB data preservation. * Make FilterBitsBuilder::FinishV2 to avoid `using FilterBitsBuilder::Finish` mess and add support for specifying a MemoryAllocator (for cache warming) Pull Request resolved: https://github.com/facebook/rocksdb/pull/9501 Test Plan: A number of obsolete tests deleted and new tests or test cases added or updated. Reviewed By: hx235 Differential Revision: D34008011 Pulled By: pdillinger fbshipit-source-id: a39a720457c354e00d5b59166b686f7f59e392aa
128 lines
5.2 KiB
C++
128 lines
5.2 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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//
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// A filter block is stored near the end of a Table file. It contains
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// filters (e.g., bloom filters) for all data blocks in the table combined
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// into a single filter block.
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#pragma once
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#include <stddef.h>
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#include <stdint.h>
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#include <memory>
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#include <string>
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#include <vector>
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#include "rocksdb/options.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/slice_transform.h"
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#include "table/block_based/filter_block_reader_common.h"
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#include "table/block_based/filter_policy_internal.h"
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#include "table/format.h"
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#include "util/hash.h"
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namespace ROCKSDB_NAMESPACE {
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// A BlockBasedFilterBlockBuilder is used to construct all of the filters for a
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// particular Table. It generates a single string which is stored as
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// a special block in the Table.
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//
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// The sequence of calls to BlockBasedFilterBlockBuilder must match the regexp:
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// (StartBlock Add*)* Finish
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class BlockBasedFilterBlockBuilder : public FilterBlockBuilder {
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public:
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BlockBasedFilterBlockBuilder(const SliceTransform* prefix_extractor,
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const BlockBasedTableOptions& table_opt,
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int bits_per_key);
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// No copying allowed
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BlockBasedFilterBlockBuilder(const BlockBasedFilterBlockBuilder&) = delete;
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void operator=(const BlockBasedFilterBlockBuilder&) = delete;
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virtual bool IsBlockBased() override { return true; }
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virtual void StartBlock(uint64_t block_offset) override;
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virtual void Add(const Slice& key_without_ts) override;
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virtual bool IsEmpty() const override {
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return start_.empty() && filter_offsets_.empty();
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}
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virtual size_t EstimateEntriesAdded() override;
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virtual Slice Finish(
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const BlockHandle& tmp, Status* status,
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std::unique_ptr<const char[]>* filter_data = nullptr) override;
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using FilterBlockBuilder::Finish;
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private:
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void AddKey(const Slice& key);
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void AddPrefix(const Slice& key);
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void GenerateFilter();
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// important: all of these might point to invalid addresses
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// at the time of destruction of this filter block. destructor
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// should NOT dereference them.
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const SliceTransform* prefix_extractor_;
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bool whole_key_filtering_;
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int bits_per_key_;
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size_t prev_prefix_start_; // the position of the last appended prefix
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// to "entries_".
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size_t prev_prefix_size_; // the length of the last appended prefix to
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// "entries_".
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std::string entries_; // Flattened entry contents
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std::vector<size_t> start_; // Starting index in entries_ of each entry
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std::string result_; // Filter data computed so far
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std::vector<Slice> tmp_entries_; // policy_->CreateFilter() argument
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std::vector<uint32_t> filter_offsets_;
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uint64_t total_added_in_built_; // Total keys added to filters built so far
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};
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// A FilterBlockReader is used to parse filter from SST table.
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// KeyMayMatch and PrefixMayMatch would trigger filter checking
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class BlockBasedFilterBlockReader
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: public FilterBlockReaderCommon<BlockContents> {
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public:
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BlockBasedFilterBlockReader(const BlockBasedTable* t,
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CachableEntry<BlockContents>&& filter_block);
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// No copying allowed
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BlockBasedFilterBlockReader(const BlockBasedFilterBlockReader&) = delete;
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void operator=(const BlockBasedFilterBlockReader&) = delete;
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static std::unique_ptr<FilterBlockReader> Create(
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const BlockBasedTable* table, const ReadOptions& ro,
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FilePrefetchBuffer* prefetch_buffer, bool use_cache, bool prefetch,
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bool pin, BlockCacheLookupContext* lookup_context);
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bool IsBlockBased() override { return true; }
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bool KeyMayMatch(const Slice& key, const SliceTransform* prefix_extractor,
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uint64_t block_offset, const bool no_io,
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const Slice* const const_ikey_ptr, GetContext* get_context,
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BlockCacheLookupContext* lookup_context) override;
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bool PrefixMayMatch(const Slice& prefix,
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const SliceTransform* prefix_extractor,
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uint64_t block_offset, const bool no_io,
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const Slice* const const_ikey_ptr,
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GetContext* get_context,
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BlockCacheLookupContext* lookup_context) override;
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size_t ApproximateMemoryUsage() const override;
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// convert this object to a human readable form
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std::string ToString() const override;
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private:
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static bool ParseFieldsFromBlock(const BlockContents& contents,
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const char** data, const char** offset,
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size_t* num, size_t* base_lg);
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bool MayMatch(const Slice& entry, uint64_t block_offset, bool no_io,
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GetContext* get_context,
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BlockCacheLookupContext* lookup_context) const;
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};
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} // namespace ROCKSDB_NAMESPACE
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