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src/Interpreters/AsynchronousInsertQueue.h

@@ -91,6 +91,9 @@ private:
         ~InsertData()
         {
             auto it = entries.begin();
+            // Entries must be destroyed in context of user who runs async insert.
+            // Each entry in the list may correspond to a different user,
+            // so we need to switch current thread's MemoryTracker parent on each iteration.
             while (it != entries.end())
             {
                 UserMemoryTrackerSwitcher switcher((*it)->user_memory_tracker);