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diff --git a/src/mongo/db/exec/change_stream_proxy.cpp b/src/mongo/db/exec/change_stream_proxy.cpp
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+++ b/src/mongo/db/exec/change_stream_proxy.cpp
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+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/exec/change_stream_proxy.h"
+
+#include "mongo/db/pipeline/pipeline_d.h"
+#include "mongo/db/pipeline/resume_token.h"
+
+namespace mongo {
+
+const char* ChangeStreamProxyStage::kStageType = "CHANGE_STREAM_PROXY";
+
+ChangeStreamProxyStage::ChangeStreamProxyStage(OperationContext* opCtx,
+                                               std::unique_ptr<Pipeline, PipelineDeleter> pipeline,
+                                               WorkingSet* ws)
+    : PipelineProxyStage(opCtx, std::move(pipeline), ws, kStageType) {
+    invariant(std::any_of(
+        _pipeline->getSources().begin(), _pipeline->getSources().end(), [](const auto& stage) {
+            return stage->constraints().isChangeStreamStage();
+        }));
+}
+
+boost::optional<BSONObj> ChangeStreamProxyStage::getNextBson() {
+    if (auto next = _pipeline->getNext()) {
+        // While we have more results to return, we track both the timestamp and the resume token of
+        // the latest event observed in the oplog, the latter via its _id field.
+        auto nextBSON = (_includeMetaData ? next->toBsonWithMetaData() : next->toBson());
+        _latestOplogTimestamp = PipelineD::getLatestOplogTimestamp(_pipeline.get());
+        if (next->getField("_id").getType() == BSONType::Object) {
+            _postBatchResumeToken = next->getField("_id").getDocument().toBson();
+        }
+        return nextBSON;
+    }
+
+    // We ran out of results to return. Check whether the oplog cursor has moved forward since the
+    // last recorded timestamp. Because we advance _latestOplogTimestamp for every event we return,
+    // if the new time is higher than the last then we are guaranteed not to have already returned
+    // any events at this timestamp. We can set _postBatchResumeToken to a new high-water-mark token
+    // at the current clusterTime.
+    auto highWaterMark = PipelineD::getLatestOplogTimestamp(_pipeline.get());
+    if (highWaterMark > _latestOplogTimestamp) {
+        auto token = ResumeToken::makeHighWaterMarkResumeToken(highWaterMark);
+        _postBatchResumeToken = token.toDocument().toBson();
+        _latestOplogTimestamp = highWaterMark;
+    }
+    return boost::none;
+}
+
+std::unique_ptr<PlanStageStats> ChangeStreamProxyStage::getStats() {
+    std::unique_ptr<PlanStageStats> ret =
+        std::make_unique<PlanStageStats>(CommonStats(kStageType), STAGE_CHANGE_STREAM_PROXY);
+    ret->specific = std::make_unique<CollectionScanStats>();
+    return ret;
+}
+
+}  // namespace mongo