diff --git a/src/Storages/S3Queue/S3QueueHolder.cpp b/src/Storages/S3Queue/S3QueueHolder.cpp
index 0900c84a2e8..7997fd2e051 100644
--- a/src/Storages/S3Queue/S3QueueHolder.cpp
+++ b/src/Storages/S3Queue/S3QueueHolder.cpp
@@ -49,6 +49,7 @@ void S3QueueHolder::S3QueueCollection::write(WriteBuffer & out) const
         out << processed_file.timestamp << "\n";
         out << processed_file.retries_count << "\n";
     }
+    /// todo(kssenii): use a more flexible format?
 }
 
 String S3QueueHolder::S3QueueCollection::toString() const
@@ -104,6 +105,7 @@ void S3QueueHolder::S3QueueProcessedCollection::add(const String & file_name)
     {
         files.erase(files.begin(), files.begin() + (files.size() - max_size));
     }
+    /// todo(kssenii): use deque here
 }
 
 
@@ -177,6 +179,7 @@ S3QueueHolder::S3QueueHolder(
 
 zkutil::ZooKeeperPtr S3QueueHolder::getZooKeeper() const
 {
+    /// todo(kssenii): current_zookeeper is not updated at all apart from in constructor, remove the lock?
     std::lock_guard lock(current_zookeeper_mutex);
     return current_zookeeper;
 }
diff --git a/src/Storages/S3Queue/S3QueueSource.cpp b/src/Storages/S3Queue/S3QueueSource.cpp
index 151b63b8051..31eda8db31f 100644
--- a/src/Storages/S3Queue/S3QueueSource.cpp
+++ b/src/Storages/S3Queue/S3QueueSource.cpp
@@ -81,6 +81,7 @@ StorageS3QueueSource::QueueGlobIterator::QueueGlobIterator(
     , glob_iterator(std::make_unique<StorageS3QueueSource::DisclosedGlobIterator>(
           client_, globbed_uri_, query, virtual_header, context, read_keys_, request_settings_))
 {
+    /// todo(kssenii): remove this loop, it should not be here
     while (true)
     {
         KeyWithInfo val = glob_iterator->next();
@@ -321,6 +322,7 @@ void StorageS3QueueSource::deleteProcessedObject(const String & file_path)
 {
     LOG_WARNING(log, "Delete processed file {} from bucket {}", file_path, bucket);
     S3::DeleteObjectRequest request;
+    /// todo(kssenii): looks incorrect
     String delete_key = file_path.substr(bucket.length() + 1);
 
     request.WithKey(delete_key).WithBucket(bucket);