diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4b976608b..2731a60ef 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -778,6 +778,8 @@ set(SOURCES
         utilities/simulator_cache/sim_cache.cc
         utilities/table_properties_collectors/compact_on_deletion_collector.cc
         utilities/trace/file_trace_reader_writer.cc
+        utilities/transactions/lock/lock_tracker.cc
+        utilities/transactions/lock/point_lock_tracker.cc
         utilities/transactions/optimistic_transaction_db_impl.cc
         utilities/transactions/optimistic_transaction.cc
         utilities/transactions/pessimistic_transaction.cc
diff --git a/TARGETS b/TARGETS
index f82ec8bcf..4fcb54fe0 100644
--- a/TARGETS
+++ b/TARGETS
@@ -358,6 +358,8 @@ cpp_library(
         "utilities/simulator_cache/sim_cache.cc",
         "utilities/table_properties_collectors/compact_on_deletion_collector.cc",
         "utilities/trace/file_trace_reader_writer.cc",
+        "utilities/transactions/lock/lock_tracker.cc",
+        "utilities/transactions/lock/point_lock_tracker.cc",
         "utilities/transactions/optimistic_transaction.cc",
         "utilities/transactions/optimistic_transaction_db_impl.cc",
         "utilities/transactions/pessimistic_transaction.cc",
diff --git a/src.mk b/src.mk
index be64083c1..a684311be 100644
--- a/src.mk
+++ b/src.mk
@@ -238,6 +238,8 @@ LIB_SOURCES =                                                   \
   utilities/simulator_cache/sim_cache.cc                        \
   utilities/table_properties_collectors/compact_on_deletion_collector.cc \
   utilities/trace/file_trace_reader_writer.cc                   \
+  utilities/transactions/lock/lock_tracker.cc                   \
+  utilities/transactions/lock/point_lock_tracker.cc             \
   utilities/transactions/optimistic_transaction.cc              \
   utilities/transactions/optimistic_transaction_db_impl.cc      \
   utilities/transactions/pessimistic_transaction.cc             \
diff --git a/utilities/transactions/lock/lock_tracker.cc b/utilities/transactions/lock/lock_tracker.cc
new file mode 100644
index 000000000..c367c273d
--- /dev/null
+++ b/utilities/transactions/lock/lock_tracker.cc
@@ -0,0 +1,17 @@
+// 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).
+
+#include "utilities/transactions/lock/lock_tracker.h"
+
+#include "utilities/transactions/lock/point_lock_tracker.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+LockTracker* NewLockTracker() {
+  // TODO: determine the lock tracker implementation based on configuration.
+  return new PointLockTracker();
+}
+
+}  // namespace ROCKSDB_NAMESPACE
diff --git a/utilities/transactions/lock/lock_tracker.h b/utilities/transactions/lock/lock_tracker.h
new file mode 100644
index 000000000..2129dd2a6
--- /dev/null
+++ b/utilities/transactions/lock/lock_tracker.h
@@ -0,0 +1,199 @@
+// 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).
+
+#pragma once
+
+#include <memory>
+
+#include "rocksdb/rocksdb_namespace.h"
+#include "rocksdb/status.h"
+#include "rocksdb/types.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+using ColumnFamilyId = uint32_t;
+
+// Request for locking a single key.
+struct PointLockRequest {
+  // The id of the key's column family.
+  ColumnFamilyId column_family_id = 0;
+  // The key to lock.
+  std::string key;
+  // The sequence number from which there is no concurrent update to key.
+  SequenceNumber seq = 0;
+  // Whether the lock is acquired only for read.
+  bool read_only = false;
+  // Whether the lock is in exclusive mode.
+  bool exclusive = true;
+};
+
+// Request for locking a range of keys.
+struct RangeLockRequest {
+  // TODO
+};
+
+struct PointLockStatus {
+  // Whether the key is locked.
+  bool locked = false;
+  // Whether the key is locked in exclusive mode.
+  bool exclusive = true;
+  // The sequence number in the tracked PointLockRequest.
+  SequenceNumber seq = 0;
+};
+
+// Return status when calling LockTracker::Untrack.
+enum class UntrackStatus {
+  // The lock is not tracked at all, so no lock to untrack.
+  NOT_TRACKED,
+  // The lock is untracked but not removed from the tracker.
+  UNTRACKED,
+  // The lock is removed from the tracker.
+  REMOVED,
+};
+
+// Tracks the lock requests.
+// In PessimisticTransaction, it tracks the locks acquired through LockMgr;
+// In OptimisticTransaction, since there is no LockMgr, it tracks the lock
+// intention. Not thread-safe.
+class LockTracker {
+ public:
+  virtual ~LockTracker() {}
+
+  // Whether supports locking a specific key.
+  virtual bool IsPointLockSupported() const = 0;
+
+  // Whether supports locking a range of keys.
+  virtual bool IsRangeLockSupported() const = 0;
+
+  // Tracks the acquirement of a lock on key.
+  //
+  // If this method is not supported, leave it as a no-op.
+  virtual void Track(const PointLockRequest& /*lock_request*/) = 0;
+
+  // Untracks the lock on a key.
+  // seq and exclusive in lock_request are not used.
+  //
+  // If this method is not supported, leave it as a no-op and
+  // returns NOT_TRACKED.
+  virtual UntrackStatus Untrack(const PointLockRequest& /*lock_request*/) = 0;
+
+  // Counterpart of Track(const PointLockRequest&) for RangeLockRequest.
+  virtual void Track(const RangeLockRequest& /*lock_request*/) = 0;
+
+  // Counterpart of Untrack(const PointLockRequest&) for RangeLockRequest.
+  virtual UntrackStatus Untrack(const RangeLockRequest& /*lock_request*/) = 0;
+
+  // Merges lock requests tracked in the specified tracker into the current
+  // tracker.
+  //
+  // E.g. for point lock, if a key in tracker is not yet tracked,
+  // track this new key; otherwise, merge the tracked information of the key
+  // such as lock's exclusiveness, read/write statistics.
+  //
+  // If this method is not supported, leave it as a no-op.
+  //
+  // REQUIRED: the specified tracker must be of the same concrete class type as
+  // the current tracker.
+  virtual void Merge(const LockTracker& /*tracker*/) = 0;
+
+  // This is a reverse operation of Merge.
+  //
+  // E.g. for point lock, if a key exists in both current and the sepcified
+  // tracker, then subtract the information (such as read/write statistics) of
+  // the key in the specified tracker from the current tracker.
+  //
+  // If this method is not supported, leave it as a no-op.
+  //
+  // REQUIRED:
+  // The specified tracker must be of the same concrete class type as
+  // the current tracker.
+  // The tracked locks in the specified tracker must be a subset of those
+  // tracked by the current tracker.
+  virtual void Subtract(const LockTracker& /*tracker*/) = 0;
+
+  // Clears all tracked locks.
+  virtual void Clear() = 0;
+
+  // Gets the new locks (excluding the locks that have been tracked before the
+  // save point) tracked since the specified save point, the result is stored
+  // in an internally constructed LockTracker and returned.
+  //
+  // save_point_tracker is the tracker used by a SavePoint to track locks
+  // tracked after creating the SavePoint.
+  //
+  // The implementation should document whether point lock, or range lock, or
+  // both are considered in this method.
+  // If this method is not supported, returns nullptr.
+  //
+  // REQUIRED:
+  // The save_point_tracker must be of the same concrete class type as the
+  // current tracker.
+  // The tracked locks in the specified tracker must be a subset of those
+  // tracked by the current tracker.
+  virtual LockTracker* GetTrackedLocksSinceSavePoint(
+      const LockTracker& /*save_point_tracker*/) const = 0;
+
+  // Gets lock related information of the key.
+  //
+  // If point lock is not supported, always returns LockStatus with
+  // locked=false.
+  virtual PointLockStatus GetPointLockStatus(
+      ColumnFamilyId /*column_family_id*/,
+      const std::string& /*key*/) const = 0;
+
+  // Gets number of tracked point locks.
+  //
+  // If point lock is not supported, always returns 0.
+  virtual uint64_t GetNumPointLocks() const = 0;
+
+  class ColumnFamilyIterator {
+   public:
+    virtual ~ColumnFamilyIterator() {}
+
+    // Whether there are remaining column families.
+    virtual bool HasNext() const = 0;
+
+    // Gets next column family id.
+    //
+    // If HasNext is false, calling this method has undefined behavior.
+    virtual ColumnFamilyId Next() = 0;
+  };
+
+  // Gets an iterator for column families.
+  //
+  // Returned iterator must not be nullptr.
+  // If there is no column family to iterate,
+  // returns an empty non-null iterator.
+  // Caller owns the returned pointer.
+  virtual ColumnFamilyIterator* GetColumnFamilyIterator() const = 0;
+
+  class KeyIterator {
+   public:
+    virtual ~KeyIterator() {}
+
+    // Whether there are remaining keys.
+    virtual bool HasNext() const = 0;
+
+    // Gets the next key.
+    //
+    // If HasNext is false, calling this method has undefined behavior.
+    virtual const std::string& Next() = 0;
+  };
+
+  // Gets an iterator for keys with tracked point locks in the column family.
+  //
+  // The column family must exist.
+  // Returned iterator must not be nullptr.
+  // Caller owns the returned pointer.
+  virtual KeyIterator* GetKeyIterator(
+      ColumnFamilyId /*column_family_id*/) const = 0;
+};
+
+// LockTracker should always be constructed through this factory method,
+// instead of constructing through concrete implementations' constructor.
+// Caller owns the returned pointer.
+LockTracker* NewLockTracker();
+
+}  // namespace ROCKSDB_NAMESPACE
diff --git a/utilities/transactions/lock/point_lock_tracker.cc b/utilities/transactions/lock/point_lock_tracker.cc
new file mode 100644
index 000000000..d6f609ee4
--- /dev/null
+++ b/utilities/transactions/lock/point_lock_tracker.cc
@@ -0,0 +1,266 @@
+// 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).
+
+#include "utilities/transactions/lock/point_lock_tracker.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+namespace {
+
+class TrackedKeysColumnFamilyIterator
+    : public LockTracker::ColumnFamilyIterator {
+ public:
+  explicit TrackedKeysColumnFamilyIterator(const TrackedKeys& keys)
+      : tracked_keys_(keys), it_(keys.begin()) {}
+
+  bool HasNext() const override { return it_ != tracked_keys_.end(); }
+
+  ColumnFamilyId Next() override { return (it_++)->first; }
+
+ private:
+  const TrackedKeys& tracked_keys_;
+  TrackedKeys::const_iterator it_;
+};
+
+class TrackedKeysIterator : public LockTracker::KeyIterator {
+ public:
+  TrackedKeysIterator(const TrackedKeys& keys, ColumnFamilyId id)
+      : key_infos_(keys.at(id)), it_(key_infos_.begin()) {}
+
+  bool HasNext() const override { return it_ != key_infos_.end(); }
+
+  const std::string& Next() override { return (it_++)->first; }
+
+ private:
+  const TrackedKeyInfos& key_infos_;
+  TrackedKeyInfos::const_iterator it_;
+};
+
+}  // namespace
+
+void PointLockTracker::Track(const PointLockRequest& r) {
+  auto& keys = tracked_keys_[r.column_family_id];
+#ifdef __cpp_lib_unordered_map_try_emplace
+  // use c++17's try_emplace if available, to avoid rehashing the key
+  // in case it is not already in the map
+  auto result = keys.try_emplace(r.key, r.seq);
+  auto it = result.first;
+  if (!result.second && r.seq < it->second.seq) {
+    // Now tracking this key with an earlier sequence number
+    it->second.seq = r.seq;
+  }
+#else
+  auto it = keys.find(r.key);
+  if (it == keys.end()) {
+    auto result = keys.emplace(r.key, TrackedKeyInfo(r.seq));
+    it = result.first;
+  } else if (r.seq < it->second.seq) {
+    // Now tracking this key with an earlier sequence number
+    it->second.seq = r.seq;
+  }
+#endif
+  // else we do not update the seq. The smaller the tracked seq, the stronger it
+  // the guarantee since it implies from the seq onward there has not been a
+  // concurrent update to the key. So we update the seq if it implies stronger
+  // guarantees, i.e., if it is smaller than the existing tracked seq.
+
+  if (r.read_only) {
+    it->second.num_reads++;
+  } else {
+    it->second.num_writes++;
+  }
+
+  it->second.exclusive = it->second.exclusive || r.exclusive;
+}
+
+UntrackStatus PointLockTracker::Untrack(const PointLockRequest& r) {
+  auto cf_keys = tracked_keys_.find(r.column_family_id);
+  if (cf_keys == tracked_keys_.end()) {
+    return UntrackStatus::NOT_TRACKED;
+  }
+
+  auto& keys = cf_keys->second;
+  auto it = keys.find(r.key);
+  if (it == keys.end()) {
+    return UntrackStatus::NOT_TRACKED;
+  }
+
+  bool untracked = false;
+  auto& info = it->second;
+  if (r.read_only) {
+    if (info.num_reads > 0) {
+      info.num_reads--;
+      untracked = true;
+    }
+  } else {
+    if (info.num_writes > 0) {
+      info.num_writes--;
+      untracked = true;
+    }
+  }
+
+  bool removed = false;
+  if (info.num_reads == 0 && info.num_writes == 0) {
+    keys.erase(it);
+    if (keys.empty()) {
+      tracked_keys_.erase(cf_keys);
+    }
+    removed = true;
+  }
+
+  if (removed) {
+    return UntrackStatus::REMOVED;
+  }
+  if (untracked) {
+    return UntrackStatus::UNTRACKED;
+  }
+  return UntrackStatus::NOT_TRACKED;
+}
+
+void PointLockTracker::Merge(const LockTracker& tracker) {
+  const PointLockTracker& t = static_cast<const PointLockTracker&>(tracker);
+  for (const auto& cf_keys : t.tracked_keys_) {
+    ColumnFamilyId cf = cf_keys.first;
+    const auto& keys = cf_keys.second;
+
+    auto current_cf_keys = tracked_keys_.find(cf);
+    if (current_cf_keys == tracked_keys_.end()) {
+      tracked_keys_.emplace(cf_keys);
+    } else {
+      auto& current_keys = current_cf_keys->second;
+      for (const auto& key_info : keys) {
+        const std::string& key = key_info.first;
+        const TrackedKeyInfo& info = key_info.second;
+        // If key was not previously tracked, just copy the whole struct over.
+        // Otherwise, some merging needs to occur.
+        auto current_info = current_keys.find(key);
+        if (current_info == current_keys.end()) {
+          current_keys.emplace(key_info);
+        } else {
+          current_info->second.Merge(info);
+        }
+      }
+    }
+  }
+}
+
+void PointLockTracker::Subtract(const LockTracker& tracker) {
+  const PointLockTracker& t = static_cast<const PointLockTracker&>(tracker);
+  for (const auto& cf_keys : t.tracked_keys_) {
+    ColumnFamilyId cf = cf_keys.first;
+    const auto& keys = cf_keys.second;
+
+    auto& current_keys = tracked_keys_.at(cf);
+    for (const auto& key_info : keys) {
+      const std::string& key = key_info.first;
+      const TrackedKeyInfo& info = key_info.second;
+      uint32_t num_reads = info.num_reads;
+      uint32_t num_writes = info.num_writes;
+
+      auto current_key_info = current_keys.find(key);
+      assert(current_key_info != current_keys.end());
+
+      // Decrement the total reads/writes of this key by the number of
+      // reads/writes done since the last SavePoint.
+      if (num_reads > 0) {
+        assert(current_key_info->second.num_reads >= num_reads);
+        current_key_info->second.num_reads -= num_reads;
+      }
+      if (num_writes > 0) {
+        assert(current_key_info->second.num_writes >= num_writes);
+        current_key_info->second.num_writes -= num_writes;
+      }
+      if (current_key_info->second.num_reads == 0 &&
+          current_key_info->second.num_writes == 0) {
+        current_keys.erase(current_key_info);
+      }
+    }
+  }
+}
+
+LockTracker* PointLockTracker::GetTrackedLocksSinceSavePoint(
+    const LockTracker& save_point_tracker) const {
+  // Examine the number of reads/writes performed on all keys written
+  // since the last SavePoint and compare to the total number of reads/writes
+  // for each key.
+  LockTracker* t = new PointLockTracker();
+  const PointLockTracker& save_point_t =
+      static_cast<const PointLockTracker&>(save_point_tracker);
+  for (const auto& cf_keys : save_point_t.tracked_keys_) {
+    ColumnFamilyId cf = cf_keys.first;
+    const auto& keys = cf_keys.second;
+
+    auto& current_keys = tracked_keys_.at(cf);
+    for (const auto& key_info : keys) {
+      const std::string& key = key_info.first;
+      const TrackedKeyInfo& info = key_info.second;
+      uint32_t num_reads = info.num_reads;
+      uint32_t num_writes = info.num_writes;
+
+      auto current_key_info = current_keys.find(key);
+      assert(current_key_info != current_keys.end());
+      assert(current_key_info->second.num_reads >= num_reads);
+      assert(current_key_info->second.num_writes >= num_writes);
+
+      if (current_key_info->second.num_reads == num_reads &&
+          current_key_info->second.num_writes == num_writes) {
+        // All the reads/writes to this key were done in the last savepoint.
+        PointLockRequest r;
+        r.column_family_id = cf;
+        r.key = key;
+        r.seq = info.seq;
+        r.read_only = (num_writes == 0);
+        r.exclusive = info.exclusive;
+        t->Track(r);
+      }
+    }
+  }
+  return t;
+}
+
+PointLockStatus PointLockTracker::GetPointLockStatus(
+    ColumnFamilyId column_family_id, const std::string& key) const {
+  assert(IsPointLockSupported());
+  PointLockStatus status;
+  auto it = tracked_keys_.find(column_family_id);
+  if (it == tracked_keys_.end()) {
+    return status;
+  }
+
+  const auto& keys = it->second;
+  auto key_it = keys.find(key);
+  if (key_it == keys.end()) {
+    return status;
+  }
+
+  const TrackedKeyInfo& key_info = key_it->second;
+  status.locked = true;
+  status.exclusive = key_info.exclusive;
+  status.seq = key_info.seq;
+  return status;
+}
+
+uint64_t PointLockTracker::GetNumPointLocks() const {
+  uint64_t num_keys = 0;
+  for (const auto& cf_keys : tracked_keys_) {
+    num_keys += cf_keys.second.size();
+  }
+  return num_keys;
+}
+
+LockTracker::ColumnFamilyIterator* PointLockTracker::GetColumnFamilyIterator()
+    const {
+  return new TrackedKeysColumnFamilyIterator(tracked_keys_);
+}
+
+LockTracker::KeyIterator* PointLockTracker::GetKeyIterator(
+    ColumnFamilyId column_family_id) const {
+  assert(tracked_keys_.find(column_family_id) != tracked_keys_.end());
+  return new TrackedKeysIterator(tracked_keys_, column_family_id);
+}
+
+void PointLockTracker::Clear() { tracked_keys_.clear(); }
+
+}  // namespace ROCKSDB_NAMESPACE
diff --git a/utilities/transactions/lock/point_lock_tracker.h b/utilities/transactions/lock/point_lock_tracker.h
new file mode 100644
index 000000000..f307d1892
--- /dev/null
+++ b/utilities/transactions/lock/point_lock_tracker.h
@@ -0,0 +1,84 @@
+// 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).
+
+#pragma once
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+#include "utilities/transactions/lock/lock_tracker.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+struct TrackedKeyInfo {
+  // Earliest sequence number that is relevant to this transaction for this key
+  SequenceNumber seq;
+
+  uint32_t num_writes;
+  uint32_t num_reads;
+
+  bool exclusive;
+
+  explicit TrackedKeyInfo(SequenceNumber seq_no)
+      : seq(seq_no), num_writes(0), num_reads(0), exclusive(false) {}
+
+  void Merge(const TrackedKeyInfo& info) {
+    assert(seq <= info.seq);
+    num_reads += info.num_reads;
+    num_writes += info.num_writes;
+    exclusive = exclusive || info.exclusive;
+  }
+};
+
+using TrackedKeyInfos = std::unordered_map<std::string, TrackedKeyInfo>;
+
+using TrackedKeys = std::unordered_map<ColumnFamilyId, TrackedKeyInfos>;
+
+// Tracks point locks on single keys.
+class PointLockTracker : public LockTracker {
+ public:
+  PointLockTracker() = default;
+
+  PointLockTracker(const PointLockTracker&) = delete;
+  PointLockTracker& operator=(const PointLockTracker&) = delete;
+
+  bool IsPointLockSupported() const override { return true; }
+
+  bool IsRangeLockSupported() const override { return false; }
+
+  void Track(const PointLockRequest& lock_request) override;
+
+  UntrackStatus Untrack(const PointLockRequest& lock_request) override;
+
+  void Track(const RangeLockRequest& /*lock_request*/) override {}
+
+  UntrackStatus Untrack(const RangeLockRequest& /*lock_request*/) override {
+    return UntrackStatus::NOT_TRACKED;
+  }
+
+  void Merge(const LockTracker& tracker) override;
+
+  void Subtract(const LockTracker& tracker) override;
+
+  void Clear() override;
+
+  virtual LockTracker* GetTrackedLocksSinceSavePoint(
+      const LockTracker& save_point_tracker) const override;
+
+  PointLockStatus GetPointLockStatus(ColumnFamilyId column_family_id,
+                                     const std::string& key) const override;
+
+  uint64_t GetNumPointLocks() const override;
+
+  ColumnFamilyIterator* GetColumnFamilyIterator() const override;
+
+  KeyIterator* GetKeyIterator(ColumnFamilyId column_family_id) const override;
+
+ private:
+  TrackedKeys tracked_keys_;
+};
+
+}  // namespace ROCKSDB_NAMESPACE
diff --git a/utilities/transactions/optimistic_transaction.cc b/utilities/transactions/optimistic_transaction.cc
index f9fb8adfa..7da2cce10 100644
--- a/utilities/transactions/optimistic_transaction.cc
+++ b/utilities/transactions/optimistic_transaction.cc
@@ -97,9 +97,17 @@ Status OptimisticTransaction::CommitWithParallelValidate() {
   const size_t space = txn_db_impl->GetLockBucketsSize();
   std::set<size_t> lk_idxes;
   std::vector<std::unique_lock<std::mutex>> lks;
-  for (auto& cfit : GetTrackedKeys()) {
-    for (auto& keyit : cfit.second) {
-      lk_idxes.insert(fastrange64(GetSliceNPHash64(keyit.first), space));
+  std::unique_ptr<LockTracker::ColumnFamilyIterator> cf_it(
+      tracked_locks_->GetColumnFamilyIterator());
+  assert(cf_it != nullptr);
+  while (cf_it->HasNext()) {
+    ColumnFamilyId cf = cf_it->Next();
+    std::unique_ptr<LockTracker::KeyIterator> key_it(
+        tracked_locks_->GetKeyIterator(cf));
+    assert(key_it != nullptr);
+    while (key_it->HasNext()) {
+      const std::string& key = key_it->Next();
+      lk_idxes.insert(fastrange64(GetSliceNPHash64(key), space));
     }
   }
   // NOTE: in a single txn, all bucket-locks are taken in ascending order.
@@ -109,7 +117,7 @@ Status OptimisticTransaction::CommitWithParallelValidate() {
     lks.emplace_back(txn_db_impl->LockBucket(v));
   }
 
-  Status s = TransactionUtil::CheckKeysForConflicts(db_impl, GetTrackedKeys(),
+  Status s = TransactionUtil::CheckKeysForConflicts(db_impl, *tracked_locks_,
                                                     true /* cache_only */);
   if (!s.ok()) {
     return s;
@@ -174,7 +182,7 @@ Status OptimisticTransaction::CheckTransactionForConflicts(DB* db) {
   // we will do a cache-only conflict check.  This can result in TryAgain
   // getting returned if there is not sufficient memtable history to check
   // for conflicts.
-  return TransactionUtil::CheckKeysForConflicts(db_impl, GetTrackedKeys(),
+  return TransactionUtil::CheckKeysForConflicts(db_impl, *tracked_locks_,
                                                 true /* cache_only */);
 }
 
diff --git a/utilities/transactions/pessimistic_transaction.cc b/utilities/transactions/pessimistic_transaction.cc
index d9851f4cd..d92818528 100644
--- a/utilities/transactions/pessimistic_transaction.cc
+++ b/utilities/transactions/pessimistic_transaction.cc
@@ -91,7 +91,7 @@ void PessimisticTransaction::Initialize(const TransactionOptions& txn_options) {
 }
 
 PessimisticTransaction::~PessimisticTransaction() {
-  txn_db_impl_->UnLock(this, &GetTrackedKeys());
+  txn_db_impl_->UnLock(this, *tracked_locks_);
   if (expiration_time_ > 0) {
     txn_db_impl_->RemoveExpirableTransaction(txn_id_);
   }
@@ -101,7 +101,7 @@ PessimisticTransaction::~PessimisticTransaction() {
 }
 
 void PessimisticTransaction::Clear() {
-  txn_db_impl_->UnLock(this, &GetTrackedKeys());
+  txn_db_impl_->UnLock(this, *tracked_locks_);
   TransactionBaseImpl::Clear();
 }
 
@@ -132,8 +132,8 @@ WriteCommittedTxn::WriteCommittedTxn(TransactionDB* txn_db,
     : PessimisticTransaction(txn_db, write_options, txn_options){};
 
 Status PessimisticTransaction::CommitBatch(WriteBatch* batch) {
-  TransactionKeyMap keys_to_unlock;
-  Status s = LockBatch(batch, &keys_to_unlock);
+  std::unique_ptr<LockTracker> keys_to_unlock(NewLockTracker());
+  Status s = LockBatch(batch, keys_to_unlock.get());
 
   if (!s.ok()) {
     return s;
@@ -164,7 +164,7 @@ Status PessimisticTransaction::CommitBatch(WriteBatch* batch) {
     s = Status::InvalidArgument("Transaction is not in state for commit.");
   }
 
-  txn_db_impl_->UnLock(this, &keys_to_unlock);
+  txn_db_impl_->UnLock(this, *keys_to_unlock);
 
   return s;
 }
@@ -446,12 +446,14 @@ Status PessimisticTransaction::RollbackToSavePoint() {
     return Status::InvalidArgument("Transaction is beyond state for rollback.");
   }
 
-  // Unlock any keys locked since last transaction
-  const std::unique_ptr<TransactionKeyMap>& keys =
-      GetTrackedKeysSinceSavePoint();
-
-  if (keys) {
-    txn_db_impl_->UnLock(this, keys.get());
+  if (save_points_ != nullptr && !save_points_->empty()) {
+    // Unlock any keys locked since last transaction
+    auto& save_point_tracker = *save_points_->top().new_locks_;
+    std::unique_ptr<LockTracker> t(
+        tracked_locks_->GetTrackedLocksSinceSavePoint(save_point_tracker));
+    if (t) {
+      txn_db_impl_->UnLock(this, *t);
+    }
   }
 
   return TransactionBaseImpl::RollbackToSavePoint();
@@ -460,7 +462,7 @@ Status PessimisticTransaction::RollbackToSavePoint() {
 // Lock all keys in this batch.
 // On success, caller should unlock keys_to_unlock
 Status PessimisticTransaction::LockBatch(WriteBatch* batch,
-                                         TransactionKeyMap* keys_to_unlock) {
+                                         LockTracker* keys_to_unlock) {
   class Handler : public WriteBatch::Handler {
    public:
     // Sorted map of column_family_id to sorted set of keys.
@@ -516,8 +518,13 @@ Status PessimisticTransaction::LockBatch(WriteBatch* batch,
       if (!s.ok()) {
         break;
       }
-      TrackKey(keys_to_unlock, cfh_id, std::move(key), kMaxSequenceNumber,
-               false, true /* exclusive */);
+      PointLockRequest r;
+      r.column_family_id = cfh_id;
+      r.key = key;
+      r.seq = kMaxSequenceNumber;
+      r.read_only = false;
+      r.exclusive = true;
+      keys_to_unlock->Track(r);
     }
 
     if (!s.ok()) {
@@ -526,7 +533,7 @@ Status PessimisticTransaction::LockBatch(WriteBatch* batch,
   }
 
   if (!s.ok()) {
-    txn_db_impl_->UnLock(this, keys_to_unlock);
+    txn_db_impl_->UnLock(this, *keys_to_unlock);
   }
 
   return s;
@@ -548,28 +555,9 @@ Status PessimisticTransaction::TryLock(ColumnFamilyHandle* column_family,
   }
   uint32_t cfh_id = GetColumnFamilyID(column_family);
   std::string key_str = key.ToString();
-  bool previously_locked;
-  bool lock_upgrade = false;
-
-  // lock this key if this transactions hasn't already locked it
-  SequenceNumber tracked_at_seq = kMaxSequenceNumber;
-
-  const auto& tracked_keys = GetTrackedKeys();
-  const auto tracked_keys_cf = tracked_keys.find(cfh_id);
-  if (tracked_keys_cf == tracked_keys.end()) {
-    previously_locked = false;
-  } else {
-    auto iter = tracked_keys_cf->second.find(key_str);
-    if (iter == tracked_keys_cf->second.end()) {
-      previously_locked = false;
-    } else {
-      if (!iter->second.exclusive && exclusive) {
-        lock_upgrade = true;
-      }
-      previously_locked = true;
-      tracked_at_seq = iter->second.seq;
-    }
-  }
+  PointLockStatus status = tracked_locks_->GetPointLockStatus(cfh_id, key_str);
+  bool previously_locked = status.locked;
+  bool lock_upgrade = previously_locked && exclusive && !status.exclusive;
 
   // Lock this key if this transactions hasn't already locked it or we require
   // an upgrade.
@@ -585,6 +573,8 @@ Status PessimisticTransaction::TryLock(ColumnFamilyHandle* column_family,
   // any writes since this transaction's snapshot.
   // TODO(agiardullo): could optimize by supporting shared txn locks in the
   // future
+  SequenceNumber tracked_at_seq =
+      status.locked ? status.seq : kMaxSequenceNumber;
   if (!do_validate || snapshot_ == nullptr) {
     if (assume_tracked && !previously_locked) {
       s = Status::InvalidArgument(
@@ -614,15 +604,13 @@ Status PessimisticTransaction::TryLock(ColumnFamilyHandle* column_family,
 
       if (!s.ok()) {
         // Failed to validate key
-        if (!previously_locked) {
-          // Unlock key we just locked
-          if (lock_upgrade) {
-            s = txn_db_impl_->TryLock(this, cfh_id, key_str,
-                                      false /* exclusive */);
-            assert(s.ok());
-          } else {
-            txn_db_impl_->UnLock(this, cfh_id, key.ToString());
-          }
+        // Unlock key we just locked
+        if (lock_upgrade) {
+          s = txn_db_impl_->TryLock(this, cfh_id, key_str,
+                                    false /* exclusive */);
+          assert(s.ok());
+        } else if (!previously_locked) {
+          txn_db_impl_->UnLock(this, cfh_id, key.ToString());
         }
       }
     }
@@ -645,10 +633,11 @@ Status PessimisticTransaction::TryLock(ColumnFamilyHandle* column_family,
       TrackKey(cfh_id, key_str, tracked_at_seq, read_only, exclusive);
     } else {
 #ifndef NDEBUG
-      assert(tracked_keys_cf->second.count(key_str) > 0);
-      const auto& info = tracked_keys_cf->second.find(key_str)->second;
-      assert(info.seq <= tracked_at_seq);
-      assert(info.exclusive == exclusive);
+      PointLockStatus lock_status =
+          tracked_locks_->GetPointLockStatus(cfh_id, key_str);
+      assert(lock_status.locked);
+      assert(lock_status.seq <= tracked_at_seq);
+      assert(lock_status.exclusive == exclusive);
 #endif
     }
   }
diff --git a/utilities/transactions/pessimistic_transaction.h b/utilities/transactions/pessimistic_transaction.h
index f81405bc3..308d7460f 100644
--- a/utilities/transactions/pessimistic_transaction.h
+++ b/utilities/transactions/pessimistic_transaction.h
@@ -139,7 +139,7 @@ class PessimisticTransaction : public TransactionBaseImpl {
 
   virtual void Initialize(const TransactionOptions& txn_options);
 
-  Status LockBatch(WriteBatch* batch, TransactionKeyMap* keys_to_unlock);
+  Status LockBatch(WriteBatch* batch, LockTracker* keys_to_unlock);
 
   Status TryLock(ColumnFamilyHandle* column_family, const Slice& key,
                  bool read_only, bool exclusive, const bool do_validate = true,
diff --git a/utilities/transactions/pessimistic_transaction_db.cc b/utilities/transactions/pessimistic_transaction_db.cc
index f68ec94ad..a15df47e1 100644
--- a/utilities/transactions/pessimistic_transaction_db.cc
+++ b/utilities/transactions/pessimistic_transaction_db.cc
@@ -402,7 +402,7 @@ Status PessimisticTransactionDB::TryLock(PessimisticTransaction* txn,
 }
 
 void PessimisticTransactionDB::UnLock(PessimisticTransaction* txn,
-                                      const TransactionKeyMap* keys) {
+                                      const LockTracker& keys) {
   lock_mgr_.UnLock(txn, keys, GetEnv());
 }
 
diff --git a/utilities/transactions/pessimistic_transaction_db.h b/utilities/transactions/pessimistic_transaction_db.h
index 144458b53..e2b548121 100644
--- a/utilities/transactions/pessimistic_transaction_db.h
+++ b/utilities/transactions/pessimistic_transaction_db.h
@@ -99,7 +99,7 @@ class PessimisticTransactionDB : public TransactionDB {
   Status TryLock(PessimisticTransaction* txn, uint32_t cfh_id,
                  const std::string& key, bool exclusive);
 
-  void UnLock(PessimisticTransaction* txn, const TransactionKeyMap* keys);
+  void UnLock(PessimisticTransaction* txn, const LockTracker& keys);
   void UnLock(PessimisticTransaction* txn, uint32_t cfh_id,
               const std::string& key);
 
diff --git a/utilities/transactions/transaction_base.cc b/utilities/transactions/transaction_base.cc
index 92b3956e1..4c4234027 100644
--- a/utilities/transactions/transaction_base.cc
+++ b/utilities/transactions/transaction_base.cc
@@ -16,6 +16,7 @@
 #include "rocksdb/status.h"
 #include "util/cast_util.h"
 #include "util/string_util.h"
+#include "utilities/transactions/lock/lock_tracker.h"
 
 namespace ROCKSDB_NAMESPACE {
 
@@ -27,6 +28,7 @@ TransactionBaseImpl::TransactionBaseImpl(DB* db,
       cmp_(GetColumnFamilyUserComparator(db->DefaultColumnFamily())),
       start_time_(db_->GetEnv()->NowMicros()),
       write_batch_(cmp_, 0, true, 0),
+      tracked_locks_(NewLockTracker()),
       indexing_enabled_(true) {
   assert(dynamic_cast<DBImpl*>(db_) != nullptr);
   log_number_ = 0;
@@ -44,7 +46,7 @@ void TransactionBaseImpl::Clear() {
   save_points_.reset(nullptr);
   write_batch_.Clear();
   commit_time_batch_.Clear();
-  tracked_keys_.clear();
+  tracked_locks_->Clear();
   num_puts_ = 0;
   num_deletes_ = 0;
   num_merges_ = 0;
@@ -143,37 +145,7 @@ Status TransactionBaseImpl::RollbackToSavePoint() {
     assert(s.ok());
 
     // Rollback any keys that were tracked since the last savepoint
-    const TransactionKeyMap& key_map = save_point.new_keys_;
-    for (const auto& key_map_iter : key_map) {
-      uint32_t column_family_id = key_map_iter.first;
-      auto& keys = key_map_iter.second;
-
-      auto& cf_tracked_keys = tracked_keys_[column_family_id];
-
-      for (const auto& key_iter : keys) {
-        const std::string& key = key_iter.first;
-        uint32_t num_reads = key_iter.second.num_reads;
-        uint32_t num_writes = key_iter.second.num_writes;
-
-        auto tracked_keys_iter = cf_tracked_keys.find(key);
-        assert(tracked_keys_iter != cf_tracked_keys.end());
-
-        // Decrement the total reads/writes of this key by the number of
-        // reads/writes done since the last SavePoint.
-        if (num_reads > 0) {
-          assert(tracked_keys_iter->second.num_reads >= num_reads);
-          tracked_keys_iter->second.num_reads -= num_reads;
-        }
-        if (num_writes > 0) {
-          assert(tracked_keys_iter->second.num_writes >= num_writes);
-          tracked_keys_iter->second.num_writes -= num_writes;
-        }
-        if (tracked_keys_iter->second.num_reads == 0 &&
-            tracked_keys_iter->second.num_writes == 0) {
-          cf_tracked_keys.erase(tracked_keys_iter);
-        }
-      }
-    }
+    tracked_locks_->Subtract(*save_point.new_locks_);
 
     save_points_->pop();
 
@@ -204,35 +176,7 @@ Status TransactionBaseImpl::PopSavePoint() {
     std::swap(top, save_points_->top());
     save_points_->pop();
 
-    const TransactionKeyMap& curr_cf_key_map = top.new_keys_;
-    TransactionKeyMap& prev_cf_key_map = save_points_->top().new_keys_;
-
-    for (const auto& curr_cf_key_iter : curr_cf_key_map) {
-      uint32_t column_family_id = curr_cf_key_iter.first;
-      const std::unordered_map<std::string, TransactionKeyMapInfo>& curr_keys =
-          curr_cf_key_iter.second;
-
-      // If cfid was not previously tracked, just copy everything over.
-      auto prev_keys_iter = prev_cf_key_map.find(column_family_id);
-      if (prev_keys_iter == prev_cf_key_map.end()) {
-        prev_cf_key_map.emplace(curr_cf_key_iter);
-      } else {
-        std::unordered_map<std::string, TransactionKeyMapInfo>& prev_keys =
-            prev_keys_iter->second;
-        for (const auto& key_iter : curr_keys) {
-          const std::string& key = key_iter.first;
-          const TransactionKeyMapInfo& info = key_iter.second;
-          // If key was not previously tracked, just copy the whole struct over.
-          // Otherwise, some merging needs to occur.
-          auto prev_info = prev_keys.find(key);
-          if (prev_info == prev_keys.end()) {
-            prev_keys.emplace(key_iter);
-          } else {
-            prev_info->second.Merge(info);
-          }
-        }
-      }
-    }
+    save_points_->top().new_locks_->Merge(*top.new_locks_);
   }
 
   return write_batch_.PopSavePoint();
@@ -601,106 +545,26 @@ uint64_t TransactionBaseImpl::GetNumDeletes() const { return num_deletes_; }
 uint64_t TransactionBaseImpl::GetNumMerges() const { return num_merges_; }
 
 uint64_t TransactionBaseImpl::GetNumKeys() const {
-  uint64_t count = 0;
-
-  // sum up locked keys in all column families
-  for (const auto& key_map_iter : tracked_keys_) {
-    const auto& keys = key_map_iter.second;
-    count += keys.size();
-  }
-
-  return count;
+  return tracked_locks_->GetNumPointLocks();
 }
 
 void TransactionBaseImpl::TrackKey(uint32_t cfh_id, const std::string& key,
                                    SequenceNumber seq, bool read_only,
                                    bool exclusive) {
+  PointLockRequest r;
+  r.column_family_id = cfh_id;
+  r.key = key;
+  r.seq = seq;
+  r.read_only = read_only;
+  r.exclusive = exclusive;
+
   // Update map of all tracked keys for this transaction
-  TrackKey(&tracked_keys_, cfh_id, key, seq, read_only, exclusive);
+  tracked_locks_->Track(r);
 
   if (save_points_ != nullptr && !save_points_->empty()) {
     // Update map of tracked keys in this SavePoint
-    TrackKey(&save_points_->top().new_keys_, cfh_id, key, seq, read_only,
-             exclusive);
-  }
-}
-
-// Add a key to the given TransactionKeyMap
-// seq for pessimistic transactions is the sequence number from which we know
-// there has not been a concurrent update to the key.
-void TransactionBaseImpl::TrackKey(TransactionKeyMap* key_map, uint32_t cfh_id,
-                                   const std::string& key, SequenceNumber seq,
-                                   bool read_only, bool exclusive) {
-  auto& cf_key_map = (*key_map)[cfh_id];
-#ifdef __cpp_lib_unordered_map_try_emplace
-  // use c++17's try_emplace if available, to avoid rehashing the key
-  // in case it is not already in the map
-  auto result = cf_key_map.try_emplace(key, seq);
-  auto iter = result.first;
-  if (!result.second && seq < iter->second.seq) {
-    // Now tracking this key with an earlier sequence number
-    iter->second.seq = seq;
-  }
-#else
-  auto iter = cf_key_map.find(key);
-  if (iter == cf_key_map.end()) {
-    auto result = cf_key_map.emplace(key, TransactionKeyMapInfo(seq));
-    iter = result.first;
-  } else if (seq < iter->second.seq) {
-    // Now tracking this key with an earlier sequence number
-    iter->second.seq = seq;
-  }
-#endif
-  // else we do not update the seq. The smaller the tracked seq, the stronger it
-  // the guarantee since it implies from the seq onward there has not been a
-  // concurrent update to the key. So we update the seq if it implies stronger
-  // guarantees, i.e., if it is smaller than the existing tracked seq.
-
-  if (read_only) {
-    iter->second.num_reads++;
-  } else {
-    iter->second.num_writes++;
-  }
-  iter->second.exclusive |= exclusive;
-}
-
-std::unique_ptr<TransactionKeyMap>
-TransactionBaseImpl::GetTrackedKeysSinceSavePoint() {
-  if (save_points_ != nullptr && !save_points_->empty()) {
-    // Examine the number of reads/writes performed on all keys written
-    // since the last SavePoint and compare to the total number of reads/writes
-    // for each key.
-    TransactionKeyMap* result = new TransactionKeyMap();
-    for (const auto& key_map_iter : save_points_->top().new_keys_) {
-      uint32_t column_family_id = key_map_iter.first;
-      auto& keys = key_map_iter.second;
-
-      auto& cf_tracked_keys = tracked_keys_[column_family_id];
-
-      for (const auto& key_iter : keys) {
-        const std::string& key = key_iter.first;
-        uint32_t num_reads = key_iter.second.num_reads;
-        uint32_t num_writes = key_iter.second.num_writes;
-
-        auto total_key_info = cf_tracked_keys.find(key);
-        assert(total_key_info != cf_tracked_keys.end());
-        assert(total_key_info->second.num_reads >= num_reads);
-        assert(total_key_info->second.num_writes >= num_writes);
-
-        if (total_key_info->second.num_reads == num_reads &&
-            total_key_info->second.num_writes == num_writes) {
-          // All the reads/writes to this key were done in the last savepoint.
-          bool read_only = (num_writes == 0);
-          TrackKey(result, column_family_id, key, key_iter.second.seq,
-                   read_only, key_iter.second.exclusive);
-        }
-      }
-    }
-    return std::unique_ptr<TransactionKeyMap>(result);
+    save_points_->top().new_locks_->Track(r);
   }
-
-  // No SavePoint
-  return nullptr;
 }
 
 // Gets the write batch that should be used for Put/Merge/Deletes.
@@ -728,54 +592,28 @@ void TransactionBaseImpl::ReleaseSnapshot(const Snapshot* snapshot, DB* db) {
 
 void TransactionBaseImpl::UndoGetForUpdate(ColumnFamilyHandle* column_family,
                                            const Slice& key) {
-  uint32_t column_family_id = GetColumnFamilyID(column_family);
-  auto& cf_tracked_keys = tracked_keys_[column_family_id];
-  std::string key_str = key.ToString();
-  bool can_decrement = false;
-  bool can_unlock __attribute__((__unused__)) = false;
+  PointLockRequest r;
+  r.column_family_id = GetColumnFamilyID(column_family);
+  r.key = key.ToString();
+  r.read_only = true;
 
+  bool can_untrack = false;
   if (save_points_ != nullptr && !save_points_->empty()) {
-    // Check if this key was fetched ForUpdate in this SavePoint
-    auto& cf_savepoint_keys = save_points_->top().new_keys_[column_family_id];
-
-    auto savepoint_iter = cf_savepoint_keys.find(key_str);
-    if (savepoint_iter != cf_savepoint_keys.end()) {
-      if (savepoint_iter->second.num_reads > 0) {
-        savepoint_iter->second.num_reads--;
-        can_decrement = true;
-
-        if (savepoint_iter->second.num_reads == 0 &&
-            savepoint_iter->second.num_writes == 0) {
-          // No other GetForUpdates or write on this key in this SavePoint
-          cf_savepoint_keys.erase(savepoint_iter);
-          can_unlock = true;
-        }
-      }
-    }
+    // If there is no GetForUpdate of the key in this save point,
+    // then cannot untrack from the global lock tracker.
+    UntrackStatus s = save_points_->top().new_locks_->Untrack(r);
+    can_untrack = (s != UntrackStatus::NOT_TRACKED);
   } else {
-    // No SavePoint set
-    can_decrement = true;
-    can_unlock = true;
-  }
-
-  // We can only decrement the read count for this key if we were able to
-  // decrement the read count in the current SavePoint, OR if there is no
-  // SavePoint set.
-  if (can_decrement) {
-    auto key_iter = cf_tracked_keys.find(key_str);
-
-    if (key_iter != cf_tracked_keys.end()) {
-      if (key_iter->second.num_reads > 0) {
-        key_iter->second.num_reads--;
-
-        if (key_iter->second.num_reads == 0 &&
-            key_iter->second.num_writes == 0) {
-          // No other GetForUpdates or writes on this key
-          assert(can_unlock);
-          cf_tracked_keys.erase(key_iter);
-          UnlockGetForUpdate(column_family, key);
-        }
-      }
+    // No save point, so can untrack from the global lock tracker.
+    can_untrack = true;
+  }
+
+  if (can_untrack) {
+    // If erased from the global tracker, then can unlock the key.
+    UntrackStatus s = tracked_locks_->Untrack(r);
+    bool can_unlock = (s == UntrackStatus::REMOVED);
+    if (can_unlock) {
+      UnlockGetForUpdate(column_family, key);
     }
   }
 }
diff --git a/utilities/transactions/transaction_base.h b/utilities/transactions/transaction_base.h
index f279676c6..c7832bdc8 100644
--- a/utilities/transactions/transaction_base.h
+++ b/utilities/transactions/transaction_base.h
@@ -1,7 +1,7 @@
 // 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).
+// 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).
 
 #pragma once
 
@@ -21,6 +21,7 @@
 #include "rocksdb/utilities/transaction_db.h"
 #include "rocksdb/utilities/write_batch_with_index.h"
 #include "util/autovector.h"
+#include "utilities/transactions/lock/lock_tracker.h"
 #include "utilities/transactions/transaction_util.h"
 
 namespace ROCKSDB_NAMESPACE {
@@ -233,10 +234,6 @@ class TransactionBaseImpl : public Transaction {
     return UndoGetForUpdate(nullptr, key);
   };
 
-  // Get list of keys in this transaction that must not have any conflicts
-  // with writes in other transactions.
-  const TransactionKeyMap& GetTrackedKeys() const { return tracked_keys_; }
-
   WriteOptions* GetWriteOptions() override { return &write_options_; }
 
   void SetWriteOptions(const WriteOptions& write_options) override {
@@ -260,17 +257,10 @@ class TransactionBaseImpl : public Transaction {
   void TrackKey(uint32_t cfh_id, const std::string& key, SequenceNumber seqno,
                 bool readonly, bool exclusive);
 
-  // Helper function to add a key to the given TransactionKeyMap
-  static void TrackKey(TransactionKeyMap* key_map, uint32_t cfh_id,
-                       const std::string& key, SequenceNumber seqno,
-                       bool readonly, bool exclusive);
-
   // Called when UndoGetForUpdate determines that this key can be unlocked.
   virtual void UnlockGetForUpdate(ColumnFamilyHandle* column_family,
                                   const Slice& key) = 0;
 
-  std::unique_ptr<TransactionKeyMap> GetTrackedKeysSinceSavePoint();
-
   // Sets a snapshot if SetSnapshotOnNextOperation() has been called.
   void SetSnapshotIfNeeded();
 
@@ -310,8 +300,8 @@ class TransactionBaseImpl : public Transaction {
     uint64_t num_deletes_ = 0;
     uint64_t num_merges_ = 0;
 
-    // Record all keys tracked since the last savepoint
-    TransactionKeyMap new_keys_;
+    // Record all locks tracked since the last savepoint
+    std::shared_ptr<LockTracker> new_locks_;
 
     SavePoint(std::shared_ptr<const Snapshot> snapshot, bool snapshot_needed,
               std::shared_ptr<TransactionNotifier> snapshot_notifier,
@@ -321,19 +311,20 @@ class TransactionBaseImpl : public Transaction {
           snapshot_notifier_(snapshot_notifier),
           num_puts_(num_puts),
           num_deletes_(num_deletes),
-          num_merges_(num_merges) {}
+          num_merges_(num_merges),
+          new_locks_(NewLockTracker()) {}
 
-    SavePoint() = default;
+    SavePoint() : new_locks_(NewLockTracker()) {}
   };
 
   // Records writes pending in this transaction
   WriteBatchWithIndex write_batch_;
 
-  // Map from column_family_id to map of keys that are involved in this
-  // transaction.
-  // For Pessimistic Transactions this is the list of locked keys.
-  // Optimistic Transactions will wait till commit time to do conflict checking.
-  TransactionKeyMap tracked_keys_;
+  // For Pessimistic Transactions this is the set of acquired locks.
+  // Optimistic Transactions will keep note the requested locks (not actually
+  // locked), and do conflict checking until commit time based on the tracked
+  // lock requests.
+  std::unique_ptr<LockTracker> tracked_locks_;
 
   // Stack of the Snapshot saved at each save point. Saved snapshots may be
   // nullptr if there was no snapshot at the time SetSavePoint() was called.
diff --git a/utilities/transactions/transaction_lock_mgr.cc b/utilities/transactions/transaction_lock_mgr.cc
index 64fe00aba..08e3b9dcf 100644
--- a/utilities/transactions/transaction_lock_mgr.cc
+++ b/utilities/transactions/transaction_lock_mgr.cc
@@ -643,26 +643,27 @@ void TransactionLockMgr::UnLock(PessimisticTransaction* txn,
 }
 
 void TransactionLockMgr::UnLock(const PessimisticTransaction* txn,
-                                const TransactionKeyMap* key_map, Env* env) {
-  for (auto& key_map_iter : *key_map) {
-    uint32_t column_family_id = key_map_iter.first;
-    auto& keys = key_map_iter.second;
-
-    std::shared_ptr<LockMap> lock_map_ptr = GetLockMap(column_family_id);
+                                const LockTracker& tracker, Env* env) {
+  std::unique_ptr<LockTracker::ColumnFamilyIterator> cf_it(
+      tracker.GetColumnFamilyIterator());
+  assert(cf_it != nullptr);
+  while (cf_it->HasNext()) {
+    ColumnFamilyId cf = cf_it->Next();
+    std::shared_ptr<LockMap> lock_map_ptr = GetLockMap(cf);
     LockMap* lock_map = lock_map_ptr.get();
-
-    if (lock_map == nullptr) {
+    if (!lock_map) {
       // Column Family must have been dropped.
       return;
     }
 
     // Bucket keys by lock_map_ stripe
     std::unordered_map<size_t, std::vector<const std::string*>> keys_by_stripe(
-        std::max(keys.size(), lock_map->num_stripes_));
-
-    for (auto& key_iter : keys) {
-      const std::string& key = key_iter.first;
-
+        lock_map->num_stripes_);
+    std::unique_ptr<LockTracker::KeyIterator> key_it(
+        tracker.GetKeyIterator(cf));
+    assert(key_it != nullptr);
+    while (key_it->HasNext()) {
+      const std::string& key = key_it->Next();
       size_t stripe_num = lock_map->GetStripe(key);
       keys_by_stripe[stripe_num].push_back(&key);
     }
diff --git a/utilities/transactions/transaction_lock_mgr.h b/utilities/transactions/transaction_lock_mgr.h
index 78c3a3809..0a9474488 100644
--- a/utilities/transactions/transaction_lock_mgr.h
+++ b/utilities/transactions/transaction_lock_mgr.h
@@ -77,7 +77,7 @@ class TransactionLockMgr {
 
   // Unlock a key locked by TryLock().  txn must be the same Transaction that
   // locked this key.
-  void UnLock(const PessimisticTransaction* txn, const TransactionKeyMap* keys,
+  void UnLock(const PessimisticTransaction* txn, const LockTracker& tracker,
               Env* env);
   void UnLock(PessimisticTransaction* txn, uint32_t column_family_id,
               const std::string& key, Env* env);
diff --git a/utilities/transactions/transaction_util.cc b/utilities/transactions/transaction_util.cc
index 45b4cb89c..494f132e7 100644
--- a/utilities/transactions/transaction_util.cc
+++ b/utilities/transactions/transaction_util.cc
@@ -137,18 +137,20 @@ Status TransactionUtil::CheckKey(DBImpl* db_impl, SuperVersion* sv,
 }
 
 Status TransactionUtil::CheckKeysForConflicts(DBImpl* db_impl,
-                                              const TransactionKeyMap& key_map,
+                                              const LockTracker& tracker,
                                               bool cache_only) {
   Status result;
 
-  for (auto& key_map_iter : key_map) {
-    uint32_t cf_id = key_map_iter.first;
-    const auto& keys = key_map_iter.second;
+  std::unique_ptr<LockTracker::ColumnFamilyIterator> cf_it(
+      tracker.GetColumnFamilyIterator());
+  assert(cf_it != nullptr);
+  while (cf_it->HasNext()) {
+    ColumnFamilyId cf = cf_it->Next();
 
-    SuperVersion* sv = db_impl->GetAndRefSuperVersion(cf_id);
+    SuperVersion* sv = db_impl->GetAndRefSuperVersion(cf);
     if (sv == nullptr) {
       result = Status::InvalidArgument("Could not access column family " +
-                                       ToString(cf_id));
+                                       ToString(cf));
       break;
     }
 
@@ -157,18 +159,21 @@ Status TransactionUtil::CheckKeysForConflicts(DBImpl* db_impl,
 
     // For each of the keys in this transaction, check to see if someone has
     // written to this key since the start of the transaction.
-    for (const auto& key_iter : keys) {
-      const auto& key = key_iter.first;
-      const SequenceNumber key_seq = key_iter.second.seq;
+    std::unique_ptr<LockTracker::KeyIterator> key_it(
+        tracker.GetKeyIterator(cf));
+    assert(key_it != nullptr);
+    while (key_it->HasNext()) {
+      const std::string& key = key_it->Next();
+      PointLockStatus status = tracker.GetPointLockStatus(cf, key);
+      const SequenceNumber key_seq = status.seq;
 
       result = CheckKey(db_impl, sv, earliest_seq, key_seq, key, cache_only);
-
       if (!result.ok()) {
         break;
       }
     }
 
-    db_impl->ReturnAndCleanupSuperVersion(cf_id, sv);
+    db_impl->ReturnAndCleanupSuperVersion(cf, sv);
 
     if (!result.ok()) {
       break;
diff --git a/utilities/transactions/transaction_util.h b/utilities/transactions/transaction_util.h
index 2e48f84a4..707d487c5 100644
--- a/utilities/transactions/transaction_util.h
+++ b/utilities/transactions/transaction_util.h
@@ -12,39 +12,14 @@
 
 #include "db/dbformat.h"
 #include "db/read_callback.h"
-
 #include "rocksdb/db.h"
 #include "rocksdb/slice.h"
 #include "rocksdb/status.h"
 #include "rocksdb/types.h"
+#include "utilities/transactions/lock/lock_tracker.h"
 
 namespace ROCKSDB_NAMESPACE {
 
-struct TransactionKeyMapInfo {
-  // Earliest sequence number that is relevant to this transaction for this key
-  SequenceNumber seq;
-
-  uint32_t num_writes;
-  uint32_t num_reads;
-
-  bool exclusive;
-
-  explicit TransactionKeyMapInfo(SequenceNumber seq_no)
-      : seq(seq_no), num_writes(0), num_reads(0), exclusive(false) {}
-
-  // Used in PopSavePoint to collapse two savepoints together.
-  void Merge(const TransactionKeyMapInfo& info) {
-    assert(seq <= info.seq);
-    num_reads += info.num_reads;
-    num_writes += info.num_writes;
-    exclusive |= info.exclusive;
-  }
-};
-
-using TransactionKeyMap =
-    std::unordered_map<uint32_t,
-                       std::unordered_map<std::string, TransactionKeyMapInfo>>;
-
 class DBImpl;
 struct SuperVersion;
 class WriteBatchWithIndex;
@@ -69,17 +44,19 @@ class TransactionUtil {
       ReadCallback* snap_checker = nullptr,
       SequenceNumber min_uncommitted = kMaxSequenceNumber);
 
-  // For each key,SequenceNumber pair in the TransactionKeyMap, this function
+  // For each key,SequenceNumber pair tracked by the LockTracker, this function
   // will verify there have been no writes to the key in the db since that
   // sequence number.
   //
   // Returns OK on success, BUSY if there is a conflicting write, or other error
   // status for any unexpected errors.
   //
-  // REQUIRED: this function should only be called on the write thread or if the
+  // REQUIRED:
+  // This function should only be called on the write thread or if the
   // mutex is held.
+  // tracker must support point lock.
   static Status CheckKeysForConflicts(DBImpl* db_impl,
-                                      const TransactionKeyMap& keys,
+                                      const LockTracker& tracker,
                                       bool cache_only);
 
  private:
diff --git a/utilities/transactions/write_unprepared_txn.cc b/utilities/transactions/write_unprepared_txn.cc
index 0f9993dca..ed2600026 100644
--- a/utilities/transactions/write_unprepared_txn.cc
+++ b/utilities/transactions/write_unprepared_txn.cc
@@ -72,10 +72,10 @@ WriteUnpreparedTxn::~WriteUnpreparedTxn() {
     }
   }
 
-  // Call tracked_keys_.clear() so that ~PessimisticTransaction does not
+  // Clear the tracked locks so that ~PessimisticTransaction does not
   // try to unlock keys for recovered transactions.
   if (recovered_txn_) {
-    tracked_keys_.clear();
+    tracked_locks_->Clear();
   }
 }
 
@@ -296,7 +296,9 @@ Status WriteUnpreparedTxn::FlushWriteBatchToDBInternal(bool prepared) {
 
     Status AddUntrackedKey(uint32_t cf, const Slice& key) {
       auto str = key.ToString();
-      if (txn_->tracked_keys_[cf].count(str) == 0) {
+      PointLockStatus lock_status =
+          txn_->tracked_locks_->GetPointLockStatus(cf, str);
+      if (!lock_status.locked) {
         txn_->untracked_keys_[cf].push_back(str);
       }
       return Status::OK();
@@ -639,8 +641,10 @@ Status WriteUnpreparedTxn::CommitInternal() {
 }
 
 Status WriteUnpreparedTxn::WriteRollbackKeys(
-    const TransactionKeyMap& tracked_keys, WriteBatchWithIndex* rollback_batch,
+    const LockTracker& lock_tracker, WriteBatchWithIndex* rollback_batch,
     ReadCallback* callback, const ReadOptions& roptions) {
+  // This assertion can be removed when range lock is supported.
+  assert(lock_tracker.IsPointLockSupported());
   const auto& cf_map = *wupt_db_->GetCFHandleMap();
   auto WriteRollbackKey = [&](const std::string& key, uint32_t cfid) {
     const auto& cf_handle = cf_map.at(cfid);
@@ -666,11 +670,17 @@ Status WriteUnpreparedTxn::WriteRollbackKeys(
     return Status::OK();
   };
 
-  for (const auto& cfkey : tracked_keys) {
-    const auto cfid = cfkey.first;
-    const auto& keys = cfkey.second;
-    for (const auto& pair : keys) {
-      auto s = WriteRollbackKey(pair.first, cfid);
+  std::unique_ptr<LockTracker::ColumnFamilyIterator> cf_it(
+      lock_tracker.GetColumnFamilyIterator());
+  assert(cf_it != nullptr);
+  while (cf_it->HasNext()) {
+    ColumnFamilyId cf = cf_it->Next();
+    std::unique_ptr<LockTracker::KeyIterator> key_it(
+        lock_tracker.GetKeyIterator(cf));
+    assert(key_it != nullptr);
+    while (key_it->HasNext()) {
+      const std::string& key = key_it->Next();
+      auto s = WriteRollbackKey(key, cf);
       if (!s.ok()) {
         return s;
       }
@@ -709,7 +719,7 @@ Status WriteUnpreparedTxn::RollbackInternal() {
   // TODO(lth): We write rollback batch all in a single batch here, but this
   // should be subdivded into multiple batches as well. In phase 2, when key
   // sets are read from WAL, this will happen naturally.
-  WriteRollbackKeys(GetTrackedKeys(), &rollback_batch, &callback, roptions);
+  WriteRollbackKeys(*tracked_locks_, &rollback_batch, &callback, roptions);
 
   // The Rollback marker will be used as a batch separator
   WriteBatchInternal::MarkRollback(rollback_batch.GetWriteBatch(), name_);
@@ -790,7 +800,7 @@ Status WriteUnpreparedTxn::RollbackInternal() {
 
 void WriteUnpreparedTxn::Clear() {
   if (!recovered_txn_) {
-    txn_db_impl_->UnLock(this, &GetTrackedKeys());
+    txn_db_impl_->UnLock(this, *tracked_locks_);
   }
   unprep_seqs_.clear();
   flushed_save_points_.reset(nullptr);
@@ -842,7 +852,7 @@ Status WriteUnpreparedTxn::RollbackToSavePointInternal() {
   WriteUnpreparedTxn::SavePoint& top = flushed_save_points_->back();
 
   assert(save_points_ != nullptr && save_points_->size() > 0);
-  const TransactionKeyMap& tracked_keys = save_points_->top().new_keys_;
+  const LockTracker& tracked_keys = *save_points_->top().new_locks_;
 
   ReadOptions roptions;
   roptions.snapshot = top.snapshot_->snapshot();
diff --git a/utilities/transactions/write_unprepared_txn.h b/utilities/transactions/write_unprepared_txn.h
index 55730e15b..5a3227f4e 100644
--- a/utilities/transactions/write_unprepared_txn.h
+++ b/utilities/transactions/write_unprepared_txn.h
@@ -212,7 +212,7 @@ class WriteUnpreparedTxn : public WritePreparedTxn {
   friend class WriteUnpreparedTxnDB;
 
   const std::map<SequenceNumber, size_t>& GetUnpreparedSequenceNumbers();
-  Status WriteRollbackKeys(const TransactionKeyMap& tracked_keys,
+  Status WriteRollbackKeys(const LockTracker& tracked_keys,
                            WriteBatchWithIndex* rollback_batch,
                            ReadCallback* callback, const ReadOptions& roptions);