diff --git a/src/Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.cpp b/src/Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.cpp
index 4aa8b12bd96..2b2570e0187 100644
--- a/src/Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.cpp
+++ b/src/Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.cpp
@@ -218,6 +218,11 @@ void ReplicatedMergeTreeBlockOutputStream::commitPart(
 
     String temporary_part_name = part->name;
 
+    /// There is one case when we need to retry transaction in a loop.
+    /// But don't do it too many times - just as defensive measure.
+    size_t loop_counter = 0;
+    constexpr size_t max_iterations = 10;
+
     while (true)
     {
         /// Obtain incremental block number and lock it. The lock holds our intention to add the block to the filesystem.
@@ -229,6 +234,10 @@ void ReplicatedMergeTreeBlockOutputStream::commitPart(
         String block_id_path = deduplicate_block ? storage.zookeeper_path + "/blocks/" + block_id : "";
         auto block_number_lock = storage.allocateBlockNumber(part->info.partition_id, zookeeper, block_id_path);
 
+        /// Prepare transaction to ZooKeeper
+        /// It will simultaneously add information about the part to all the necessary places in ZooKeeper and remove block_number_lock.
+        Coordination::Requests ops;
+
         Int64 block_number = 0;
         String existing_part_name;
         if (block_number_lock)
@@ -242,6 +251,25 @@ void ReplicatedMergeTreeBlockOutputStream::commitPart(
             part->info.level = 0;
 
             part->name = part->getNewName(part->info);
+
+            /// Will add log entry about new part.
+
+            StorageReplicatedMergeTree::LogEntry log_entry;
+            log_entry.type = StorageReplicatedMergeTree::LogEntry::GET_PART;
+            log_entry.create_time = time(nullptr);
+            log_entry.source_replica = storage.replica_name;
+            log_entry.new_part_name = part->name;
+            log_entry.quorum = quorum;
+            log_entry.block_id = block_id;
+            log_entry.new_part_type = part->getType();
+
+            ops.emplace_back(zkutil::makeCreateRequest(
+                storage.zookeeper_path + "/log/log-",
+                log_entry.toString(),
+                zkutil::CreateMode::PersistentSequential));
+
+            /// Deletes the information that the block number is used for writing.
+            block_number_lock->getUnlockOps(ops);
         }
         else
         {
@@ -269,43 +297,21 @@ void ReplicatedMergeTreeBlockOutputStream::commitPart(
             part->name = existing_part_name;
             part->info = MergeTreePartInfo::fromPartName(existing_part_name, storage.format_version);
 
+            /// Used only for exception messages.
             block_number = part->info.min_block;
 
             /// Don't do subsequent duplicate check.
             block_id_path.clear();
         }
 
-        StorageReplicatedMergeTree::LogEntry log_entry;
-        log_entry.type = StorageReplicatedMergeTree::LogEntry::GET_PART;
-        log_entry.create_time = time(nullptr);
-        log_entry.source_replica = storage.replica_name;
-        log_entry.new_part_name = part->name;
-        log_entry.quorum = quorum;
-        log_entry.block_id = block_id;
-        log_entry.new_part_type = part->getType();
-
-        /// Simultaneously add information about the part to all the necessary places in ZooKeeper and remove block_number_lock.
-
         /// Information about the part.
-        Coordination::Requests ops;
-
         storage.getCommitPartOps(ops, part, block_id_path);
 
-        /// Replication log.
-        ops.emplace_back(zkutil::makeCreateRequest(
-            storage.zookeeper_path + "/log/log-",
-            log_entry.toString(),
-            zkutil::CreateMode::PersistentSequential));
-
-        /// Deletes the information that the block number is used for writing.
-        if (block_number_lock)
-            block_number_lock->getUnlockOps(ops);
-
-        /** If you need a quorum - create a node in which the quorum is monitored.
-        * (If such a node already exists, then someone has managed to make another quorum record at the same time,
-        *  but for it the quorum has not yet been reached.
-        *  You can not do the next quorum record at this time.)
-        */
+        /** If we need a quorum - create a node in which the quorum is monitored.
+          * (If such a node already exists, then someone has managed to make another quorum record at the same time,
+          *  but for it the quorum has not yet been reached.
+          *  You can not do the next quorum record at this time.)
+          */
         if (quorum) /// TODO Duplicate blocks.
         {
             ReplicatedMergeTreeQuorumEntry quorum_entry;
@@ -405,6 +411,9 @@ void ReplicatedMergeTreeBlockOutputStream::commitPart(
                 part->state = MergeTreeDataPartState::Temporary;
                 part->renameTo(temporary_part_name, false);
 
+                ++loop_counter;
+                if (loop_counter == max_iterations)
+                    throw Exception("Too many transaction retires - it may indicate an error", ErrorCodes::DUPLICATE_DATA_PART);
                 continue;
             }
             else if (multi_code == Coordination::Error::ZNODEEXISTS && failed_op_path == quorum_info.status_path)