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diff --git a/src/rocksdb/db/version_edit.h b/src/rocksdb/db/version_edit.h
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+++ b/src/rocksdb/db/version_edit.h
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+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+#include <algorithm>
+#include <set>
+#include <string>
+#include <utility>
+#include <vector>
+#include "db/dbformat.h"
+#include "memory/arena.h"
+#include "rocksdb/cache.h"
+#include "table/table_reader.h"
+#include "util/autovector.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class VersionSet;
+
+constexpr uint64_t kFileNumberMask = 0x3FFFFFFFFFFFFFFF;
+constexpr uint64_t kInvalidBlobFileNumber = 0;
+constexpr uint64_t kUnknownOldestAncesterTime = 0;
+constexpr uint64_t kUnknownFileCreationTime = 0;
+
+extern const std::string kUnknownFileChecksum;
+extern const std::string kUnknownFileChecksumFuncName;
+
+extern uint64_t PackFileNumberAndPathId(uint64_t number, uint64_t path_id);
+
+// A copyable structure contains information needed to read data from an SST
+// file. It can contain a pointer to a table reader opened for the file, or
+// file number and size, which can be used to create a new table reader for it.
+// The behavior is undefined when a copied of the structure is used when the
+// file is not in any live version any more.
+struct FileDescriptor {
+  // Table reader in table_reader_handle
+  TableReader* table_reader;
+  uint64_t packed_number_and_path_id;
+  uint64_t file_size;  // File size in bytes
+  SequenceNumber smallest_seqno;  // The smallest seqno in this file
+  SequenceNumber largest_seqno;   // The largest seqno in this file
+
+  FileDescriptor() : FileDescriptor(0, 0, 0) {}
+
+  FileDescriptor(uint64_t number, uint32_t path_id, uint64_t _file_size)
+      : FileDescriptor(number, path_id, _file_size, kMaxSequenceNumber, 0) {}
+
+  FileDescriptor(uint64_t number, uint32_t path_id, uint64_t _file_size,
+                 SequenceNumber _smallest_seqno, SequenceNumber _largest_seqno)
+      : table_reader(nullptr),
+        packed_number_and_path_id(PackFileNumberAndPathId(number, path_id)),
+        file_size(_file_size),
+        smallest_seqno(_smallest_seqno),
+        largest_seqno(_largest_seqno) {}
+
+  FileDescriptor(const FileDescriptor& fd) { *this = fd; }
+
+  FileDescriptor& operator=(const FileDescriptor& fd) {
+    table_reader = fd.table_reader;
+    packed_number_and_path_id = fd.packed_number_and_path_id;
+    file_size = fd.file_size;
+    smallest_seqno = fd.smallest_seqno;
+    largest_seqno = fd.largest_seqno;
+    return *this;
+  }
+
+  uint64_t GetNumber() const {
+    return packed_number_and_path_id & kFileNumberMask;
+  }
+  uint32_t GetPathId() const {
+    return static_cast<uint32_t>(
+        packed_number_and_path_id / (kFileNumberMask + 1));
+  }
+  uint64_t GetFileSize() const { return file_size; }
+};
+
+struct FileSampledStats {
+  FileSampledStats() : num_reads_sampled(0) {}
+  FileSampledStats(const FileSampledStats& other) { *this = other; }
+  FileSampledStats& operator=(const FileSampledStats& other) {
+    num_reads_sampled = other.num_reads_sampled.load();
+    return *this;
+  }
+
+  // number of user reads to this file.
+  mutable std::atomic<uint64_t> num_reads_sampled;
+};
+
+struct FileMetaData {
+  FileDescriptor fd;
+  InternalKey smallest;            // Smallest internal key served by table
+  InternalKey largest;             // Largest internal key served by table
+
+  // Needs to be disposed when refs becomes 0.
+  Cache::Handle* table_reader_handle = nullptr;
+
+  FileSampledStats stats;
+
+  // Stats for compensating deletion entries during compaction
+
+  // File size compensated by deletion entry.
+  // This is updated in Version::UpdateAccumulatedStats() first time when the
+  // file is created or loaded.  After it is updated (!= 0), it is immutable.
+  uint64_t compensated_file_size = 0;
+  // These values can mutate, but they can only be read or written from
+  // single-threaded LogAndApply thread
+  uint64_t num_entries = 0;     // the number of entries.
+  uint64_t num_deletions = 0;   // the number of deletion entries.
+  uint64_t raw_key_size = 0;    // total uncompressed key size.
+  uint64_t raw_value_size = 0;  // total uncompressed value size.
+
+  int refs = 0;  // Reference count
+
+  bool being_compacted = false;       // Is this file undergoing compaction?
+  bool init_stats_from_file = false;  // true if the data-entry stats of this
+                                      // file has initialized from file.
+
+  bool marked_for_compaction = false;  // True if client asked us nicely to
+                                       // compact this file.
+
+  // Used only in BlobDB. The file number of the oldest blob file this SST file
+  // refers to. 0 is an invalid value; BlobDB numbers the files starting from 1.
+  uint64_t oldest_blob_file_number = kInvalidBlobFileNumber;
+
+  // The file could be the compaction output from other SST files, which could
+  // in turn be outputs for compact older SST files. We track the memtable
+  // flush timestamp for the oldest SST file that eventaully contribute data
+  // to this file. 0 means the information is not available.
+  uint64_t oldest_ancester_time = kUnknownOldestAncesterTime;
+
+  // Unix time when the SST file is created.
+  uint64_t file_creation_time = kUnknownFileCreationTime;
+
+  // File checksum
+  std::string file_checksum = kUnknownFileChecksum;
+
+  // File checksum function name
+  std::string file_checksum_func_name = kUnknownFileChecksumFuncName;
+
+  FileMetaData() = default;
+
+  FileMetaData(uint64_t file, uint32_t file_path_id, uint64_t file_size,
+               const InternalKey& smallest_key, const InternalKey& largest_key,
+               const SequenceNumber& smallest_seq,
+               const SequenceNumber& largest_seq, bool marked_for_compact,
+               uint64_t oldest_blob_file, uint64_t _oldest_ancester_time,
+               uint64_t _file_creation_time, const std::string& _file_checksum,
+               const std::string& _file_checksum_func_name)
+      : fd(file, file_path_id, file_size, smallest_seq, largest_seq),
+        smallest(smallest_key),
+        largest(largest_key),
+        marked_for_compaction(marked_for_compact),
+        oldest_blob_file_number(oldest_blob_file),
+        oldest_ancester_time(_oldest_ancester_time),
+        file_creation_time(_file_creation_time),
+        file_checksum(_file_checksum),
+        file_checksum_func_name(_file_checksum_func_name) {
+    TEST_SYNC_POINT_CALLBACK("FileMetaData::FileMetaData", this);
+  }
+
+  // REQUIRED: Keys must be given to the function in sorted order (it expects
+  // the last key to be the largest).
+  void UpdateBoundaries(const Slice& key, const Slice& value,
+                        SequenceNumber seqno, ValueType value_type);
+
+  // Unlike UpdateBoundaries, ranges do not need to be presented in any
+  // particular order.
+  void UpdateBoundariesForRange(const InternalKey& start,
+                                const InternalKey& end, SequenceNumber seqno,
+                                const InternalKeyComparator& icmp) {
+    if (smallest.size() == 0 || icmp.Compare(start, smallest) < 0) {
+      smallest = start;
+    }
+    if (largest.size() == 0 || icmp.Compare(largest, end) < 0) {
+      largest = end;
+    }
+    fd.smallest_seqno = std::min(fd.smallest_seqno, seqno);
+    fd.largest_seqno = std::max(fd.largest_seqno, seqno);
+  }
+
+  // Try to get oldest ancester time from the class itself or table properties
+  // if table reader is already pinned.
+  // 0 means the information is not available.
+  uint64_t TryGetOldestAncesterTime() {
+    if (oldest_ancester_time != kUnknownOldestAncesterTime) {
+      return oldest_ancester_time;
+    } else if (fd.table_reader != nullptr &&
+               fd.table_reader->GetTableProperties() != nullptr) {
+      return fd.table_reader->GetTableProperties()->creation_time;
+    }
+    return kUnknownOldestAncesterTime;
+  }
+
+  uint64_t TryGetFileCreationTime() {
+    if (file_creation_time != kUnknownFileCreationTime) {
+      return file_creation_time;
+    } else if (fd.table_reader != nullptr &&
+               fd.table_reader->GetTableProperties() != nullptr) {
+      return fd.table_reader->GetTableProperties()->file_creation_time;
+    }
+    return kUnknownFileCreationTime;
+  }
+};
+
+// A compressed copy of file meta data that just contain minimum data needed
+// to server read operations, while still keeping the pointer to full metadata
+// of the file in case it is needed.
+struct FdWithKeyRange {
+  FileDescriptor fd;
+  FileMetaData* file_metadata;  // Point to all metadata
+  Slice smallest_key;    // slice that contain smallest key
+  Slice largest_key;     // slice that contain largest key
+
+  FdWithKeyRange()
+      : fd(),
+        file_metadata(nullptr),
+        smallest_key(),
+        largest_key() {
+  }
+
+  FdWithKeyRange(FileDescriptor _fd, Slice _smallest_key, Slice _largest_key,
+                 FileMetaData* _file_metadata)
+      : fd(_fd),
+        file_metadata(_file_metadata),
+        smallest_key(_smallest_key),
+        largest_key(_largest_key) {}
+};
+
+// Data structure to store an array of FdWithKeyRange in one level
+// Actual data is guaranteed to be stored closely
+struct LevelFilesBrief {
+  size_t num_files;
+  FdWithKeyRange* files;
+  LevelFilesBrief() {
+    num_files = 0;
+    files = nullptr;
+  }
+};
+
+// The state of a DB at any given time is referred to as a Version.
+// Any modification to the Version is considered a Version Edit. A Version is
+// constructed by joining a sequence of Version Edits. Version Edits are written
+// to the MANIFEST file.
+class VersionEdit {
+ public:
+  void Clear();
+
+  void SetDBId(const std::string& db_id) {
+    has_db_id_ = true;
+    db_id_ = db_id;
+  }
+  bool HasDbId() const { return has_db_id_; }
+  const std::string& GetDbId() const { return db_id_; }
+
+  void SetComparatorName(const Slice& name) {
+    has_comparator_ = true;
+    comparator_ = name.ToString();
+  }
+  bool HasComparatorName() const { return has_comparator_; }
+  const std::string& GetComparatorName() const { return comparator_; }
+
+  void SetLogNumber(uint64_t num) {
+    has_log_number_ = true;
+    log_number_ = num;
+  }
+  bool HasLogNumber() const { return has_log_number_; }
+  uint64_t GetLogNumber() const { return log_number_; }
+
+  void SetPrevLogNumber(uint64_t num) {
+    has_prev_log_number_ = true;
+    prev_log_number_ = num;
+  }
+  bool HasPrevLogNumber() const { return has_prev_log_number_; }
+  uint64_t GetPrevLogNumber() const { return prev_log_number_; }
+
+  void SetNextFile(uint64_t num) {
+    has_next_file_number_ = true;
+    next_file_number_ = num;
+  }
+  bool HasNextFile() const { return has_next_file_number_; }
+  uint64_t GetNextFile() const { return next_file_number_; }
+
+  void SetMaxColumnFamily(uint32_t max_column_family) {
+    has_max_column_family_ = true;
+    max_column_family_ = max_column_family;
+  }
+  bool HasMaxColumnFamily() const { return has_max_column_family_; }
+  uint32_t GetMaxColumnFamily() const { return max_column_family_; }
+
+  void SetMinLogNumberToKeep(uint64_t num) {
+    has_min_log_number_to_keep_ = true;
+    min_log_number_to_keep_ = num;
+  }
+  bool HasMinLogNumberToKeep() const { return has_min_log_number_to_keep_; }
+  uint64_t GetMinLogNumberToKeep() const { return min_log_number_to_keep_; }
+
+  void SetLastSequence(SequenceNumber seq) {
+    has_last_sequence_ = true;
+    last_sequence_ = seq;
+  }
+  bool HasLastSequence() const { return has_last_sequence_; }
+  SequenceNumber GetLastSequence() const { return last_sequence_; }
+
+  // Delete the specified "file" from the specified "level".
+  void DeleteFile(int level, uint64_t file) {
+    deleted_files_.emplace(level, file);
+  }
+
+  // Retrieve the files deleted as well as their associated levels.
+  using DeletedFiles = std::set<std::pair<int, uint64_t>>;
+  const DeletedFiles& GetDeletedFiles() const { return deleted_files_; }
+
+  // Add the specified file at the specified level.
+  // REQUIRES: This version has not been saved (see VersionSet::SaveTo)
+  // REQUIRES: "smallest" and "largest" are smallest and largest keys in file
+  // REQUIRES: "oldest_blob_file_number" is the number of the oldest blob file
+  // referred to by this file if any, kInvalidBlobFileNumber otherwise.
+  void AddFile(int level, uint64_t file, uint32_t file_path_id,
+               uint64_t file_size, const InternalKey& smallest,
+               const InternalKey& largest, const SequenceNumber& smallest_seqno,
+               const SequenceNumber& largest_seqno, bool marked_for_compaction,
+               uint64_t oldest_blob_file_number, uint64_t oldest_ancester_time,
+               uint64_t file_creation_time, const std::string& file_checksum,
+               const std::string& file_checksum_func_name) {
+    assert(smallest_seqno <= largest_seqno);
+    new_files_.emplace_back(
+        level, FileMetaData(file, file_path_id, file_size, smallest, largest,
+                            smallest_seqno, largest_seqno,
+                            marked_for_compaction, oldest_blob_file_number,
+                            oldest_ancester_time, file_creation_time,
+                            file_checksum, file_checksum_func_name));
+  }
+
+  void AddFile(int level, const FileMetaData& f) {
+    assert(f.fd.smallest_seqno <= f.fd.largest_seqno);
+    new_files_.emplace_back(level, f);
+  }
+
+  // Retrieve the files added as well as their associated levels.
+  using NewFiles = std::vector<std::pair<int, FileMetaData>>;
+  const NewFiles& GetNewFiles() const { return new_files_; }
+
+  // Number of edits
+  size_t NumEntries() const { return new_files_.size() + deleted_files_.size(); }
+
+  void SetColumnFamily(uint32_t column_family_id) {
+    column_family_ = column_family_id;
+  }
+  uint32_t GetColumnFamily() const { return column_family_; }
+
+  // set column family ID by calling SetColumnFamily()
+  void AddColumnFamily(const std::string& name) {
+    assert(!is_column_family_drop_);
+    assert(!is_column_family_add_);
+    assert(NumEntries() == 0);
+    is_column_family_add_ = true;
+    column_family_name_ = name;
+  }
+
+  // set column family ID by calling SetColumnFamily()
+  void DropColumnFamily() {
+    assert(!is_column_family_drop_);
+    assert(!is_column_family_add_);
+    assert(NumEntries() == 0);
+    is_column_family_drop_ = true;
+  }
+
+  bool IsColumnFamilyManipulation() const {
+    return is_column_family_add_ || is_column_family_drop_;
+  }
+
+  void MarkAtomicGroup(uint32_t remaining_entries) {
+    is_in_atomic_group_ = true;
+    remaining_entries_ = remaining_entries;
+  }
+  bool IsInAtomicGroup() const { return is_in_atomic_group_; }
+  uint32_t GetRemainingEntries() const { return remaining_entries_; }
+
+  // return true on success.
+  bool EncodeTo(std::string* dst) const;
+  Status DecodeFrom(const Slice& src);
+
+  std::string DebugString(bool hex_key = false) const;
+  std::string DebugJSON(int edit_num, bool hex_key = false) const;
+
+ private:
+  friend class ReactiveVersionSet;
+  friend class VersionSet;
+  friend class Version;
+  friend class AtomicGroupReadBuffer;
+
+  bool GetLevel(Slice* input, int* level, const char** msg);
+
+  const char* DecodeNewFile4From(Slice* input);
+
+  int max_level_ = 0;
+  std::string db_id_;
+  std::string comparator_;
+  uint64_t log_number_ = 0;
+  uint64_t prev_log_number_ = 0;
+  uint64_t next_file_number_ = 0;
+  uint32_t max_column_family_ = 0;
+  // The most recent WAL log number that is deleted
+  uint64_t min_log_number_to_keep_ = 0;
+  SequenceNumber last_sequence_ = 0;
+  bool has_db_id_ = false;
+  bool has_comparator_ = false;
+  bool has_log_number_ = false;
+  bool has_prev_log_number_ = false;
+  bool has_next_file_number_ = false;
+  bool has_max_column_family_ = false;
+  bool has_min_log_number_to_keep_ = false;
+  bool has_last_sequence_ = false;
+
+  DeletedFiles deleted_files_;
+  NewFiles new_files_;
+
+  // Each version edit record should have column_family_ set
+  // If it's not set, it is default (0)
+  uint32_t column_family_ = 0;
+  // a version edit can be either column_family add or
+  // column_family drop. If it's column family add,
+  // it also includes column family name.
+  bool is_column_family_drop_ = false;
+  bool is_column_family_add_ = false;
+  std::string column_family_name_;
+
+  bool is_in_atomic_group_ = false;
+  uint32_t remaining_entries_ = 0;
+};
+
+}  // namespace ROCKSDB_NAMESPACE