diff --git a/src/Processors/QueryPlan/ReadFromMergeTree.cpp b/src/Processors/QueryPlan/ReadFromMergeTree.cpp
index 8c7a4d86e5b..8deab0ae6c8 100644
--- a/src/Processors/QueryPlan/ReadFromMergeTree.cpp
+++ b/src/Processors/QueryPlan/ReadFromMergeTree.cpp
@@ -837,6 +837,7 @@ Pipe ReadFromMergeTree::spreadMarkRangesAmongStreamsWithOrder(
     };
 
     Pipes pipes;
+    /// For parallel replicas the split will be performed on the initiator side.
     if (is_parallel_reading_from_replicas)
     {
         pipes.emplace_back(readInOrder(std::move(parts_with_ranges), column_names, pool_settings, read_type, input_order_info->limit));
diff --git a/src/Storages/MergeTree/IMergeTreeReadPool.h b/src/Storages/MergeTree/IMergeTreeReadPool.h
index 904933a8410..944d933e167 100644
--- a/src/Storages/MergeTree/IMergeTreeReadPool.h
+++ b/src/Storages/MergeTree/IMergeTreeReadPool.h
@@ -22,7 +22,7 @@ public:
     virtual bool preservesOrderOfRanges() const = 0;
 
     /// task_idx is an implementation defined identifier that helps
-    /// to get required task. E.g. it may be number of thread, index of
+    /// to get required task. E.g. it may be number of thread in case of Default reading type or an index of a part in case of InOrder/InReverseOrder reading type.
     virtual MergeTreeReadTaskPtr getTask(size_t task_idx, MergeTreeReadTask * previous_task) = 0;
     virtual void profileFeedback(ReadBufferFromFileBase::ProfileInfo info) = 0;
 };