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diff --git a/src/rocksdb/db/compaction/compaction_outputs.h b/src/rocksdb/db/compaction/compaction_outputs.h
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+++ b/src/rocksdb/db/compaction/compaction_outputs.h
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+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  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 "db/blob/blob_garbage_meter.h"
+#include "db/compaction/compaction.h"
+#include "db/compaction/compaction_iterator.h"
+#include "db/internal_stats.h"
+#include "db/output_validator.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class CompactionOutputs;
+using CompactionFileOpenFunc = std::function<Status(CompactionOutputs&)>;
+using CompactionFileCloseFunc =
+    std::function<Status(CompactionOutputs&, const Status&, const Slice&)>;
+
+// Files produced by subcompaction, most of the functions are used by
+// compaction_job Open/Close compaction file functions.
+class CompactionOutputs {
+ public:
+  // compaction output file
+  struct Output {
+    Output(FileMetaData&& _meta, const InternalKeyComparator& _icmp,
+           bool _enable_order_check, bool _enable_hash, bool _finished,
+           uint64_t precalculated_hash)
+        : meta(std::move(_meta)),
+          validator(_icmp, _enable_order_check, _enable_hash,
+                    precalculated_hash),
+          finished(_finished) {}
+    FileMetaData meta;
+    OutputValidator validator;
+    bool finished;
+    std::shared_ptr<const TableProperties> table_properties;
+  };
+
+  CompactionOutputs() = delete;
+
+  explicit CompactionOutputs(const Compaction* compaction,
+                             const bool is_penultimate_level);
+
+  // Add generated output to the list
+  void AddOutput(FileMetaData&& meta, const InternalKeyComparator& icmp,
+                 bool enable_order_check, bool enable_hash,
+                 bool finished = false, uint64_t precalculated_hash = 0) {
+    outputs_.emplace_back(std::move(meta), icmp, enable_order_check,
+                          enable_hash, finished, precalculated_hash);
+  }
+
+  // Set new table builder for the current output
+  void NewBuilder(const TableBuilderOptions& tboptions);
+
+  // Assign a new WritableFileWriter to the current output
+  void AssignFileWriter(WritableFileWriter* writer) {
+    file_writer_.reset(writer);
+  }
+
+  // TODO: Remove it when remote compaction support tiered compaction
+  void SetTotalBytes(uint64_t bytes) { stats_.bytes_written += bytes; }
+  void SetNumOutputRecords(uint64_t num) { stats_.num_output_records = num; }
+
+  // TODO: Move the BlobDB builder into CompactionOutputs
+  const std::vector<BlobFileAddition>& GetBlobFileAdditions() const {
+    if (is_penultimate_level_) {
+      assert(blob_file_additions_.empty());
+    }
+    return blob_file_additions_;
+  }
+
+  std::vector<BlobFileAddition>* GetBlobFileAdditionsPtr() {
+    assert(!is_penultimate_level_);
+    return &blob_file_additions_;
+  }
+
+  bool HasBlobFileAdditions() const { return !blob_file_additions_.empty(); }
+
+  BlobGarbageMeter* CreateBlobGarbageMeter() {
+    assert(!is_penultimate_level_);
+    blob_garbage_meter_ = std::make_unique<BlobGarbageMeter>();
+    return blob_garbage_meter_.get();
+  }
+
+  BlobGarbageMeter* GetBlobGarbageMeter() const {
+    if (is_penultimate_level_) {
+      // blobdb doesn't support per_key_placement yet
+      assert(blob_garbage_meter_ == nullptr);
+      return nullptr;
+    }
+    return blob_garbage_meter_.get();
+  }
+
+  void UpdateBlobStats() {
+    assert(!is_penultimate_level_);
+    stats_.num_output_files_blob = blob_file_additions_.size();
+    for (const auto& blob : blob_file_additions_) {
+      stats_.bytes_written_blob += blob.GetTotalBlobBytes();
+    }
+  }
+
+  // Finish the current output file
+  Status Finish(const Status& intput_status,
+                const SeqnoToTimeMapping& seqno_time_mapping);
+
+  // Update output table properties from table builder
+  void UpdateTableProperties() {
+    current_output().table_properties =
+        std::make_shared<TableProperties>(GetTableProperties());
+  }
+
+  IOStatus WriterSyncClose(const Status& intput_status, SystemClock* clock,
+                           Statistics* statistics, bool use_fsync);
+
+  TableProperties GetTableProperties() {
+    return builder_->GetTableProperties();
+  }
+
+  Slice SmallestUserKey() const {
+    if (!outputs_.empty() && outputs_[0].finished) {
+      return outputs_[0].meta.smallest.user_key();
+    } else {
+      return Slice{nullptr, 0};
+    }
+  }
+
+  Slice LargestUserKey() const {
+    if (!outputs_.empty() && outputs_.back().finished) {
+      return outputs_.back().meta.largest.user_key();
+    } else {
+      return Slice{nullptr, 0};
+    }
+  }
+
+  // In case the last output file is empty, which doesn't need to keep.
+  void RemoveLastEmptyOutput() {
+    if (!outputs_.empty() && !outputs_.back().meta.fd.file_size) {
+      // An error occurred, so ignore the last output.
+      outputs_.pop_back();
+    }
+  }
+
+  // Remove the last output, for example the last output doesn't have data (no
+  // entry and no range-dels), but file_size might not be 0, as it has SST
+  // metadata.
+  void RemoveLastOutput() {
+    assert(!outputs_.empty());
+    outputs_.pop_back();
+  }
+
+  bool HasBuilder() const { return builder_ != nullptr; }
+
+  FileMetaData* GetMetaData() { return &current_output().meta; }
+
+  bool HasOutput() const { return !outputs_.empty(); }
+
+  uint64_t NumEntries() const { return builder_->NumEntries(); }
+
+  void ResetBuilder() {
+    builder_.reset();
+    current_output_file_size_ = 0;
+  }
+
+  // Add range-dels from the aggregator to the current output file
+  // @param comp_start_user_key and comp_end_user_key include timestamp if
+  // user-defined timestamp is enabled.
+  // @param full_history_ts_low used for range tombstone garbage collection.
+  Status AddRangeDels(const Slice* comp_start_user_key,
+                      const Slice* comp_end_user_key,
+                      CompactionIterationStats& range_del_out_stats,
+                      bool bottommost_level, const InternalKeyComparator& icmp,
+                      SequenceNumber earliest_snapshot,
+                      const Slice& next_table_min_key,
+                      const std::string& full_history_ts_low);
+
+  // if the outputs have range delete, range delete is also data
+  bool HasRangeDel() const {
+    return range_del_agg_ && !range_del_agg_->IsEmpty();
+  }
+
+ private:
+  friend class SubcompactionState;
+
+  void FillFilesToCutForTtl();
+
+  void SetOutputSlitKey(const std::optional<Slice> start,
+                        const std::optional<Slice> end) {
+    const InternalKeyComparator* icmp =
+        &compaction_->column_family_data()->internal_comparator();
+
+    const InternalKey* output_split_key = compaction_->GetOutputSplitKey();
+    // Invalid output_split_key indicates that we do not need to split
+    if (output_split_key != nullptr) {
+      // We may only split the output when the cursor is in the range. Split
+      if ((!end.has_value() ||
+           icmp->user_comparator()->Compare(
+               ExtractUserKey(output_split_key->Encode()), end.value()) < 0) &&
+          (!start.has_value() || icmp->user_comparator()->Compare(
+                                     ExtractUserKey(output_split_key->Encode()),
+                                     start.value()) > 0)) {
+        local_output_split_key_ = output_split_key;
+      }
+    }
+  }
+
+  // Returns true iff we should stop building the current output
+  // before processing the current key in compaction iterator.
+  bool ShouldStopBefore(const CompactionIterator& c_iter);
+
+  void Cleanup() {
+    if (builder_ != nullptr) {
+      // May happen if we get a shutdown call in the middle of compaction
+      builder_->Abandon();
+      builder_.reset();
+    }
+  }
+
+  // update tracked grandparents information like grandparent index, if it's
+  // in the gap between 2 grandparent files, accumulated grandparent files size
+  // etc.
+  // It returns how many boundaries it crosses by including current key.
+  size_t UpdateGrandparentBoundaryInfo(const Slice& internal_key);
+
+  // helper function to get the overlapped grandparent files size, it's only
+  // used for calculating the first key's overlap.
+  uint64_t GetCurrentKeyGrandparentOverlappedBytes(
+      const Slice& internal_key) const;
+
+  // Add current key from compaction_iterator to the output file. If needed
+  // close and open new compaction output with the functions provided.
+  Status AddToOutput(const CompactionIterator& c_iter,
+                     const CompactionFileOpenFunc& open_file_func,
+                     const CompactionFileCloseFunc& close_file_func);
+
+  // Close the current output. `open_file_func` is needed for creating new file
+  // for range-dels only output file.
+  Status CloseOutput(const Status& curr_status,
+                     const CompactionFileOpenFunc& open_file_func,
+                     const CompactionFileCloseFunc& close_file_func) {
+    Status status = curr_status;
+    // handle subcompaction containing only range deletions
+    if (status.ok() && !HasBuilder() && !HasOutput() && HasRangeDel()) {
+      status = open_file_func(*this);
+    }
+    if (HasBuilder()) {
+      const Slice empty_key{};
+      Status s = close_file_func(*this, status, empty_key);
+      if (!s.ok() && status.ok()) {
+        status = s;
+      }
+    }
+
+    return status;
+  }
+
+  // This subcompaction's output could be empty if compaction was aborted before
+  // this subcompaction had a chance to generate any output files. When
+  // subcompactions are executed sequentially this is more likely and will be
+  // particularly likely for the later subcompactions to be empty. Once they are
+  // run in parallel however it should be much rarer.
+  // It's caller's responsibility to make sure it's not empty.
+  Output& current_output() {
+    assert(!outputs_.empty());
+    return outputs_.back();
+  }
+
+  // Assign the range_del_agg to the target output level. There's only one
+  // range-del-aggregator per compaction outputs, for
+  // output_to_penultimate_level compaction it is only assigned to the
+  // penultimate level.
+  void AssignRangeDelAggregator(
+      std::unique_ptr<CompactionRangeDelAggregator>&& range_del_agg) {
+    assert(range_del_agg_ == nullptr);
+    range_del_agg_ = std::move(range_del_agg);
+  }
+
+  const Compaction* compaction_;
+
+  // current output builder and writer
+  std::unique_ptr<TableBuilder> builder_;
+  std::unique_ptr<WritableFileWriter> file_writer_;
+  uint64_t current_output_file_size_ = 0;
+
+  // all the compaction outputs so far
+  std::vector<Output> outputs_;
+
+  // BlobDB info
+  std::vector<BlobFileAddition> blob_file_additions_;
+  std::unique_ptr<BlobGarbageMeter> blob_garbage_meter_;
+
+  // Basic compaction output stats for this level's outputs
+  InternalStats::CompactionOutputsStats stats_;
+
+  // indicate if this CompactionOutputs obj for penultimate_level, should always
+  // be false if per_key_placement feature is not enabled.
+  const bool is_penultimate_level_;
+  std::unique_ptr<CompactionRangeDelAggregator> range_del_agg_ = nullptr;
+
+  // partitioner information
+  std::string last_key_for_partitioner_;
+  std::unique_ptr<SstPartitioner> partitioner_;
+
+  // A flag determines if this subcompaction has been split by the cursor
+  bool is_split_ = false;
+
+  // We also maintain the output split key for each subcompaction to avoid
+  // repetitive comparison in ShouldStopBefore()
+  const InternalKey* local_output_split_key_ = nullptr;
+
+  // Some identified files with old oldest ancester time and the range should be
+  // isolated out so that the output file(s) in that range can be merged down
+  // for TTL and clear the timestamps for the range.
+  std::vector<FileMetaData*> files_to_cut_for_ttl_;
+  int cur_files_to_cut_for_ttl_ = -1;
+  int next_files_to_cut_for_ttl_ = 0;
+
+  // An index that used to speed up ShouldStopBefore().
+  size_t grandparent_index_ = 0;
+
+  // if the output key is being grandparent files gap, so:
+  //  key > grandparents[grandparent_index_ - 1].largest &&
+  //  key < grandparents[grandparent_index_].smallest
+  bool being_grandparent_gap_ = true;
+
+  // The number of bytes overlapping between the current output and
+  // grandparent files used in ShouldStopBefore().
+  uint64_t grandparent_overlapped_bytes_ = 0;
+
+  // A flag determines whether the key has been seen in ShouldStopBefore()
+  bool seen_key_ = false;
+
+  // for the current output file, how many file boundaries has it crossed,
+  // basically number of files overlapped * 2
+  size_t grandparent_boundary_switched_num_ = 0;
+};
+
+// helper struct to concatenate the last level and penultimate level outputs
+// which could be replaced by std::ranges::join_view() in c++20
+struct OutputIterator {
+ public:
+  explicit OutputIterator(const std::vector<CompactionOutputs::Output>& a,
+                          const std::vector<CompactionOutputs::Output>& b)
+      : a_(a), b_(b) {
+    within_a = !a_.empty();
+    idx_ = 0;
+  }
+
+  OutputIterator begin() { return *this; }
+
+  OutputIterator end() { return *this; }
+
+  size_t size() { return a_.size() + b_.size(); }
+
+  const CompactionOutputs::Output& operator*() const {
+    return within_a ? a_[idx_] : b_[idx_];
+  }
+
+  OutputIterator& operator++() {
+    idx_++;
+    if (within_a && idx_ >= a_.size()) {
+      within_a = false;
+      idx_ = 0;
+    }
+    assert(within_a || idx_ <= b_.size());
+    return *this;
+  }
+
+  bool operator!=(const OutputIterator& /*rhs*/) const {
+    return within_a || idx_ < b_.size();
+  }
+
+ private:
+  const std::vector<CompactionOutputs::Output>& a_;
+  const std::vector<CompactionOutputs::Output>& b_;
+  bool within_a;
+  size_t idx_;
+};
+
+}  // namespace ROCKSDB_NAMESPACE