f7489123e2
Summary: Compaction picker and internal key comparator are different for each column family (not global), so they should live in ColumnFamilyData Test Plan: make check Reviewers: dhruba, haobo CC: leveldb Differential Revision: https://reviews.facebook.net/D15801
228 lines
7.9 KiB
C++
228 lines
7.9 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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// Copyright (c) 2011 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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#pragma once
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#include <unordered_map>
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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 "db/memtablelist.h"
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#include "db/write_batch_internal.h"
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namespace rocksdb {
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class Version;
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class VersionSet;
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class MemTable;
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class MemTableListVersion;
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class CompactionPicker;
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class Compaction;
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class InternalKey;
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// holds references to memtable, all immutable memtables and version
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struct SuperVersion {
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MemTable* mem;
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MemTableListVersion* imm;
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Version* current;
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std::atomic<uint32_t> refs;
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// We need to_delete because during Cleanup(), imm->Unref() returns
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// all memtables that we need to free through this vector. We then
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// delete all those memtables outside of mutex, during destruction
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std::vector<MemTable*> to_delete;
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// should be called outside the mutex
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SuperVersion();
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~SuperVersion();
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SuperVersion* Ref();
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// Returns true if this was the last reference and caller should
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// call Clenaup() and delete the object
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bool Unref();
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// call these two methods with db mutex held
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// Cleanup unrefs mem, imm and current. Also, it stores all memtables
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// that needs to be deleted in to_delete vector. Unrefing those
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// objects needs to be done in the mutex
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void Cleanup();
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void Init(MemTable* new_mem, MemTableListVersion* new_imm,
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Version* new_current);
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};
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// column family metadata. not thread-safe. should be protected by db_mutex
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class ColumnFamilyData {
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public:
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ColumnFamilyData(uint32_t id, const std::string& name,
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Version* dummy_versions, const ColumnFamilyOptions& options);
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~ColumnFamilyData();
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uint32_t GetID() const { return id_; }
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const std::string& GetName() { return name_; }
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int NumberLevels() const { return options_.num_levels; }
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void SetLogNumber(uint64_t log_number) { log_number_ = log_number; }
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uint64_t GetLogNumber() const { return log_number_; }
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ColumnFamilyOptions* options() { return &options_; }
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MemTableList* imm() { return &imm_; }
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MemTable* mem() { return mem_; }
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Version* current() { return current_; }
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Version* dummy_versions() { return dummy_versions_; }
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void SetMemtable(MemTable* new_mem) { mem_ = new_mem; }
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void SetCurrent(Version* current);
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void CreateNewMemtable();
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// See documentation in compaction_picker.h
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Compaction* PickCompaction();
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Compaction* CompactRange(int input_level, int output_level,
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const InternalKey* begin, const InternalKey* end,
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InternalKey** compaction_end);
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CompactionPicker* compaction_picker() const {
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return compaction_picker_.get();
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}
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const InternalKeyComparator& internal_comparator() const { return icmp_; }
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SuperVersion* GetSuperVersion() const { return super_version_; }
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uint64_t GetSuperVersionNumber() const {
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return super_version_number_.load();
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}
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// will return a pointer to SuperVersion* if previous SuperVersion
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// if its reference count is zero and needs deletion or nullptr if not
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// As argument takes a pointer to allocated SuperVersion to enable
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// the clients to allocate SuperVersion outside of mutex.
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SuperVersion* InstallSuperVersion(SuperVersion* new_superversion);
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// A Flag indicating whether write needs to slowdown because of there are
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// too many number of level0 files.
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bool NeedSlowdownForNumLevel0Files() const {
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return need_slowdown_for_num_level0_files_;
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}
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private:
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friend class ColumnFamilySet;
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ColumnFamilyData* next() { return next_.load(); }
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uint32_t id_;
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const std::string name_;
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Version* dummy_versions_; // Head of circular doubly-linked list of versions.
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Version* current_; // == dummy_versions->prev_
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ColumnFamilyOptions options_;
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const InternalKeyComparator icmp_;
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MemTable* mem_;
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MemTableList imm_;
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SuperVersion* super_version_;
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// An ordinal representing the current SuperVersion. Updated by
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// InstallSuperVersion(), i.e. incremented every time super_version_
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// changes.
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std::atomic<uint64_t> super_version_number_;
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// pointers for a circular linked list. we use it to support iterations
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// that can be concurrent with writes
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std::atomic<ColumnFamilyData*> next_;
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std::atomic<ColumnFamilyData*> prev_;
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// This is the earliest log file number that contains data from this
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// Column Family. All earlier log files must be ignored and not
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// recovered from
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uint64_t log_number_;
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// A flag indicating whether we should delay writes because
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// we have too many level 0 files
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bool need_slowdown_for_num_level0_files_;
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// An object that keeps all the compaction stats
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// and picks the next compaction
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std::unique_ptr<CompactionPicker> compaction_picker_;
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};
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// Thread safe only for reading without a writer. All access should be
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// locked when adding or dropping column family
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class ColumnFamilySet {
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public:
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class iterator {
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public:
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explicit iterator(ColumnFamilyData* cfd)
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: current_(cfd) {}
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iterator& operator++() {
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current_ = current_->next();
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return *this;
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}
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bool operator!=(const iterator& other) {
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return this->current_ != other.current_;
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}
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ColumnFamilyData* operator*() { return current_; }
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private:
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ColumnFamilyData* current_;
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};
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ColumnFamilySet();
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~ColumnFamilySet();
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ColumnFamilyData* GetDefault() const;
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// GetColumnFamily() calls return nullptr if column family is not found
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ColumnFamilyData* GetColumnFamily(uint32_t id) const;
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bool Exists(uint32_t id);
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bool Exists(const std::string& name);
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uint32_t GetID(const std::string& name);
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// this call will return the next available column family ID. it guarantees
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// that there is no column family with id greater than or equal to the
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// returned value in the current running instance. It does not, however,
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// guarantee that the returned ID is unique accross RocksDB restarts.
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// For example, if a client adds a column family 6 and then drops it,
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// after a restart, we might reuse column family 6 ID.
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uint32_t GetNextColumnFamilyID();
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ColumnFamilyData* CreateColumnFamily(const std::string& name, uint32_t id,
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Version* dummy_version,
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const ColumnFamilyOptions& options);
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void DropColumnFamily(uint32_t id);
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iterator begin() { return iterator(dummy_cfd_->next()); }
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iterator end() { return iterator(dummy_cfd_); }
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private:
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std::unordered_map<std::string, uint32_t> column_families_;
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std::unordered_map<uint32_t, ColumnFamilyData*> column_family_data_;
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// we need to keep them alive because we still can't control the lifetime of
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// all of column family data members (options for example)
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std::vector<ColumnFamilyData*> droppped_column_families_;
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uint32_t max_column_family_;
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ColumnFamilyData* dummy_cfd_;
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};
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class ColumnFamilyMemTablesImpl : public ColumnFamilyMemTables {
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public:
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explicit ColumnFamilyMemTablesImpl(ColumnFamilySet* column_family_set)
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: column_family_set_(column_family_set), log_number_(0) {}
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// If column_family_data->log_number is bigger than log_number,
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// the memtable will not be returned.
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// If log_number == 0, the memtable will be always returned
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void SetLogNumber(uint64_t log_number) { log_number_ = log_number; }
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// Returns the column families memtable if log_number == 0 || log_number <=
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// column_family_data->log_number.
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// If column family doesn't exist, it asserts
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virtual MemTable* GetMemTable(uint32_t column_family_id) override;
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private:
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ColumnFamilySet* column_family_set_;
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uint64_t log_number_;
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};
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} // namespace rocksdb
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