diff --git a/dbms/include/DB/Storages/StorageMergeTree.h b/dbms/include/DB/Storages/StorageMergeTree.h
index 58a3ffef05b..055a1a3d604 100644
--- a/dbms/include/DB/Storages/StorageMergeTree.h
+++ b/dbms/include/DB/Storages/StorageMergeTree.h
@@ -119,9 +119,12 @@ private:
 	MergeTreeDataWriter writer;
 	MergeTreeDataMerger merger;
 
-	/// Для нумерации блоков.
+	/// For block numbers.
 	SimpleIncrement increment;
 
+	/// For clearOldParts, clearOldTemporaryDirectories.
+	StopwatchWithLock time_after_previous_cleanup;
+
 	MergeTreeData::DataParts currently_merging;
 	std::mutex currently_merging_mutex;
 
diff --git a/dbms/src/Storages/StorageMergeTree.cpp b/dbms/src/Storages/StorageMergeTree.cpp
index 83ad8df32d4..f178b1b6464 100644
--- a/dbms/src/Storages/StorageMergeTree.cpp
+++ b/dbms/src/Storages/StorageMergeTree.cpp
@@ -297,9 +297,12 @@ bool StorageMergeTree::merge(
 	const String & partition,
 	bool final)
 {
-	/// Удаляем старые куски.
-	data.clearOldParts();
-	data.clearOldTemporaryDirectories();	/// TODO Делать это реже.
+	/// Clear old parts. It does not matter to do it more frequently than each second.
+	if (time_after_previous_cleanup.lockTestAndRestart(1))
+	{
+		data.clearOldParts();
+		data.clearOldTemporaryDirectories();
+	}
 
 	auto structure_lock = lockStructure(true);