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diff --git a/src/rocksdb/table/two_level_iterator.h b/src/rocksdb/table/two_level_iterator.h
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+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+#include "rocksdb/env.h"
+#include "rocksdb/iterator.h"
+#include "table/iterator_wrapper.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+struct ReadOptions;
+class InternalKeyComparator;
+
+// TwoLevelIteratorState expects iterators are not created using the arena
+struct TwoLevelIteratorState {
+  TwoLevelIteratorState() {}
+
+  virtual ~TwoLevelIteratorState() {}
+  virtual InternalIteratorBase<IndexValue>* NewSecondaryIterator(
+      const BlockHandle& handle) = 0;
+};
+
+// Return a new two level iterator.  A two-level iterator contains an
+// index iterator whose values point to a sequence of blocks where
+// each block is itself a sequence of key,value pairs.  The returned
+// two-level iterator yields the concatenation of all key/value pairs
+// in the sequence of blocks.  Takes ownership of "index_iter" and
+// will delete it when no longer needed.
+//
+// Uses a supplied function to convert an index_iter value into
+// an iterator over the contents of the corresponding block.
+// Note: this function expects first_level_iter was not created using the arena
+extern InternalIteratorBase<IndexValue>* NewTwoLevelIterator(
+    TwoLevelIteratorState* state,
+    InternalIteratorBase<IndexValue>* first_level_iter);
+
+}  // namespace ROCKSDB_NAMESPACE