Revert "SERVER-19355 mongos issues sortKey meta-projection in order to perform sorted merge"

This reverts commit eed4c7978289968e54ff4510c5bbfab808a21fb0.

10 files changed, 27 insertions, 420 deletions

diff --git a/src/mongo/s/query/SConscript b/src/mongo/s/query/SConscript
index 13e67f7fd35..317dcdf2942 100644
--- a/src/mongo/s/query/SConscript
+++ b/src/mongo/s/query/SConscript
@@ -31,7 +31,6 @@ env.Library(
         "router_stage_limit.cpp",
         "router_stage_merge.cpp",
         "router_stage_mock.cpp",
-        "router_stage_remove_sortkey.cpp",
         "router_stage_skip.cpp",
     ],
     LIBDEPS=[
@@ -43,7 +42,6 @@ env.CppUnitTest(
     target="router_exec_stage_test",
     source=[
         "router_stage_limit_test.cpp",
-        "router_stage_remove_sortkey_test.cpp",
         "router_stage_skip_test.cpp",
     ],
     LIBDEPS=[
@@ -55,7 +53,6 @@ env.Library(
     target="async_results_merger",
     source=[
         "async_results_merger.cpp",
-        "cluster_client_cursor_params.cpp",
     ],
     LIBDEPS=[
         "$BUILD_DIR/mongo/db/query/command_request_response",
diff --git a/src/mongo/s/query/async_results_merger.cpp b/src/mongo/s/query/async_results_merger.cpp
index 57441815d92..73f67095547 100644
--- a/src/mongo/s/query/async_results_merger.cpp
+++ b/src/mongo/s/query/async_results_merger.cpp
@@ -357,16 +357,6 @@ void AsyncResultsMerger::handleBatchResponse(
     remote.cursorId = getMoreResponse.cursorId;
 
     for (const auto& obj : getMoreResponse.batch) {
-        // If there's a sort, we're expecting the remote node to give us back a sort key.
-        if (!_params.sort.isEmpty() &&
-            obj[ClusterClientCursorParams::kSortKeyField].type() != BSONType::Object) {
-            remote.status = Status(ErrorCodes::InternalError,
-                                   str::stream() << "Missing field '"
-                                                 << ClusterClientCursorParams::kSortKeyField
-                                                 << "' in document: " << obj);
-            return;
-        }
-
         remote.docBuffer.push(obj);
         ++remote.fetchedCount;
     }
@@ -511,10 +501,7 @@ bool AsyncResultsMerger::MergingComparator::operator()(const size_t& lhs, const
     const BSONObj& leftDoc = _remotes[lhs].docBuffer.front();
     const BSONObj& rightDoc = _remotes[rhs].docBuffer.front();
 
-    BSONObj leftDocKey = leftDoc[ClusterClientCursorParams::kSortKeyField].Obj();
-    BSONObj rightDocKey = rightDoc[ClusterClientCursorParams::kSortKeyField].Obj();
-
-    return leftDocKey.woCompare(rightDocKey, _sort, false /*considerFieldName*/) > 0;
+    return leftDoc.woSortOrder(rightDoc, _sort, true /*useDotted*/) > 0;
 }
 
 }  // namespace mongo
diff --git a/src/mongo/s/query/async_results_merger_test.cpp b/src/mongo/s/query/async_results_merger_test.cpp
index c02db414282..7542d182f66 100644
--- a/src/mongo/s/query/async_results_merger_test.cpp
+++ b/src/mongo/s/query/async_results_merger_test.cpp
@@ -291,30 +291,27 @@ TEST_F(AsyncResultsMergerTest, ClusterFindSorted) {
     ASSERT_FALSE(arm->ready());
 
     std::vector<GetMoreResponse> responses;
-    std::vector<BSONObj> batch1 = {fromjson("{_id: 5, $sortKey: {'': 5}}"),
-                                   fromjson("{_id: 6, $sortKey: {'': 6}}")};
+    std::vector<BSONObj> batch1 = {fromjson("{_id: 5}"), fromjson("{_id: 6}")};
     responses.emplace_back(_nss, CursorId(0), batch1);
-    std::vector<BSONObj> batch2 = {fromjson("{_id: 3, $sortKey: {'': 3}}"),
-                                   fromjson("{_id: 9, $sortKey: {'': 9}}")};
+    std::vector<BSONObj> batch2 = {fromjson("{_id: 3}"), fromjson("{_id: 9}")};
     responses.emplace_back(_nss, CursorId(0), batch2);
-    std::vector<BSONObj> batch3 = {fromjson("{_id: 4, $sortKey: {'': 4}}"),
-                                   fromjson("{_id: 8, $sortKey: {'': 8}}")};
+    std::vector<BSONObj> batch3 = {fromjson("{_id: 4}"), fromjson("{_id: 8}")};
     responses.emplace_back(_nss, CursorId(0), batch3);
     scheduleNetworkResponses(responses);
     executor->waitForEvent(readyEvent);
 
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{_id: 3, $sortKey: {'': 3}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 3}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{_id: 4, $sortKey: {'': 4}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 4}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{_id: 5, $sortKey: {'': 5}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 5}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{_id: 6, $sortKey: {'': 6}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 6}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{_id: 8, $sortKey: {'': 8}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 8}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{_id: 9, $sortKey: {'': 9}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 9}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
     ASSERT(!unittest::assertGet(arm->nextReady()));
 }
@@ -328,128 +325,61 @@ TEST_F(AsyncResultsMergerTest, ClusterFindAndGetMoreSorted) {
     ASSERT_FALSE(arm->ready());
 
     std::vector<GetMoreResponse> responses;
-    std::vector<BSONObj> batch1 = {fromjson("{$sortKey: {'': 5}}"),
-                                   fromjson("{$sortKey: {'': 6}}")};
+    std::vector<BSONObj> batch1 = {fromjson("{_id: 5}"), fromjson("{_id: 6}")};
     responses.emplace_back(_nss, CursorId(1), batch1);
-    std::vector<BSONObj> batch2 = {fromjson("{$sortKey: {'': 3}}"),
-                                   fromjson("{$sortKey: {'': 4}}")};
+    std::vector<BSONObj> batch2 = {fromjson("{_id: 3}"), fromjson("{_id: 4}")};
     responses.emplace_back(_nss, CursorId(0), batch2);
-    std::vector<BSONObj> batch3 = {fromjson("{$sortKey: {'': 7}}"),
-                                   fromjson("{$sortKey: {'': 8}}")};
+    std::vector<BSONObj> batch3 = {fromjson("{_id: 7}"), fromjson("{_id: 8}")};
     responses.emplace_back(_nss, CursorId(2), batch3);
     scheduleNetworkResponses(responses);
     executor->waitForEvent(readyEvent);
 
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 3}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 3}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 4}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 4}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 5}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 5}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 6}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 6}"), *unittest::assertGet(arm->nextReady()));
 
     ASSERT_FALSE(arm->ready());
     readyEvent = unittest::assertGet(arm->nextEvent());
     ASSERT_FALSE(arm->ready());
 
     responses.clear();
-    std::vector<BSONObj> batch4 = {fromjson("{$sortKey: {'': 7}}"),
-                                   fromjson("{$sortKey: {'': 10}}")};
+    std::vector<BSONObj> batch4 = {fromjson("{_id: 7}"), fromjson("{_id: 10}")};
     responses.emplace_back(_nss, CursorId(0), batch4);
     scheduleNetworkResponses(responses);
     executor->waitForEvent(readyEvent);
 
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 7}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 7}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 7}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 7}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 8}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 8}"), *unittest::assertGet(arm->nextReady()));
 
     ASSERT_FALSE(arm->ready());
     readyEvent = unittest::assertGet(arm->nextEvent());
     ASSERT_FALSE(arm->ready());
 
     responses.clear();
-    std::vector<BSONObj> batch5 = {fromjson("{$sortKey: {'': 9}}"),
-                                   fromjson("{$sortKey: {'': 10}}")};
+    std::vector<BSONObj> batch5 = {fromjson("{_id: 9}"), fromjson("{_id: 10}")};
     responses.emplace_back(_nss, CursorId(0), batch5);
     scheduleNetworkResponses(responses);
     executor->waitForEvent(readyEvent);
 
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 9}}"), *unittest::assertGet(arm->nextReady()));
-    ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 10}}"), *unittest::assertGet(arm->nextReady()));
-    ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 10}}"), *unittest::assertGet(arm->nextReady()));
-    ASSERT_TRUE(arm->ready());
-    ASSERT(!unittest::assertGet(arm->nextReady()));
-}
-
-TEST_F(AsyncResultsMergerTest, ClusterFindCompoundSortKey) {
-    BSONObj findCmd = fromjson("{find: 'testcoll', sort: {a: -1, b: 1}, batchSize: 2}");
-    makeCursorFromFindCmd(findCmd, _remotes);
-
-    ASSERT_FALSE(arm->ready());
-    auto readyEvent = unittest::assertGet(arm->nextEvent());
-    ASSERT_FALSE(arm->ready());
-
-    std::vector<GetMoreResponse> responses;
-    std::vector<BSONObj> batch1 = {fromjson("{$sortKey: {'': 5, '': 9}}"),
-                                   fromjson("{$sortKey: {'': 4, '': 20}}")};
-    responses.emplace_back(_nss, CursorId(0), batch1);
-    std::vector<BSONObj> batch2 = {fromjson("{$sortKey: {'': 10, '': 11}}"),
-                                   fromjson("{$sortKey: {'': 4, '': 4}}")};
-    responses.emplace_back(_nss, CursorId(0), batch2);
-    std::vector<BSONObj> batch3 = {fromjson("{$sortKey: {'': 10, '': 12}}"),
-                                   fromjson("{$sortKey: {'': 5, '': 9}}")};
-    responses.emplace_back(_nss, CursorId(0), batch3);
-    scheduleNetworkResponses(responses);
-    executor->waitForEvent(readyEvent);
-
-    ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 10, '': 11}}"), *unittest::assertGet(arm->nextReady()));
-    ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 10, '': 12}}"), *unittest::assertGet(arm->nextReady()));
-    ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 5, '': 9}}"), *unittest::assertGet(arm->nextReady()));
-    ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 5, '': 9}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 9}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 4, '': 4}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 10}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
-    ASSERT_EQ(fromjson("{$sortKey: {'': 4, '': 20}}"), *unittest::assertGet(arm->nextReady()));
+    ASSERT_EQ(fromjson("{_id: 10}"), *unittest::assertGet(arm->nextReady()));
     ASSERT_TRUE(arm->ready());
     ASSERT(!unittest::assertGet(arm->nextReady()));
 }
 
-TEST_F(AsyncResultsMergerTest, ClusterFindSortedButNoSortKey) {
-    BSONObj findCmd = fromjson("{find: 'testcoll', sort: {a: -1, b: 1}, batchSize: 2}");
-    makeCursorFromFindCmd(findCmd, {_remotes[0]});
-
-    ASSERT_FALSE(arm->ready());
-    auto readyEvent = unittest::assertGet(arm->nextEvent());
-    ASSERT_FALSE(arm->ready());
-
-    // Parsing the batch results in an error because the sort key is missing.
-    std::vector<GetMoreResponse> responses;
-    std::vector<BSONObj> batch1 = {fromjson("{a: 2, b: 1}"), fromjson("{a: 1, b: 2}")};
-    responses.emplace_back(_nss, CursorId(1), batch1);
-    scheduleNetworkResponses(responses);
-    executor->waitForEvent(readyEvent);
-
-    ASSERT_TRUE(arm->ready());
-    auto statusWithNext = arm->nextReady();
-    ASSERT(!statusWithNext.isOK());
-    ASSERT_EQ(statusWithNext.getStatus().code(), ErrorCodes::InternalError);
-
-    // Required to kill the 'arm' on error before destruction.
-    auto killEvent = arm->kill();
-    executor->waitForEvent(killEvent);
-}
-
 TEST_F(AsyncResultsMergerTest, ClusterFindInitialBatchSizeIsZero) {
     // Initial batchSize sent with the find command is zero; batchSize sent with each getMore
     // command is one.
diff --git a/src/mongo/s/query/cluster_client_cursor_impl.cpp b/src/mongo/s/query/cluster_client_cursor_impl.cpp
index b371b858338..2662eb1a405 100644
--- a/src/mongo/s/query/cluster_client_cursor_impl.cpp
+++ b/src/mongo/s/query/cluster_client_cursor_impl.cpp
@@ -35,7 +35,6 @@
 #include "mongo/s/query/router_stage_limit.h"
 #include "mongo/s/query/router_stage_merge.h"
 #include "mongo/s/query/router_stage_mock.h"
-#include "mongo/s/query/router_stage_remove_sortkey.h"
 #include "mongo/s/query/router_stage_skip.h"
 #include "mongo/stdx/memory.h"
 
@@ -82,10 +81,6 @@ std::unique_ptr<RouterExecStage> ClusterClientCursorImpl::buildMergerPlan(
         root = stdx::make_unique<RouterStageLimit>(std::move(root), *params.limit);
     }
 
-    if (!params.sort.isEmpty()) {
-        root = stdx::make_unique<RouterStageRemoveSortKey>(std::move(root));
-    }
-
     return root;
 }
 
diff --git a/src/mongo/s/query/cluster_client_cursor_params.cpp b/src/mongo/s/query/cluster_client_cursor_params.cpp
deleted file mode 100644
index a9c583e80ef..00000000000
--- a/src/mongo/s/query/cluster_client_cursor_params.cpp
+++ /dev/null
@@ -1,37 +0,0 @@
-/**
- *    Copyright (C) 2015 MongoDB Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    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
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    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 GNU Affero General 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/s/query/cluster_client_cursor_params.h"
-
-namespace mongo {
-
-const char ClusterClientCursorParams::kSortKeyField[] = "$sortKey";
-
-}  // namespace mongo
diff --git a/src/mongo/s/query/cluster_client_cursor_params.h b/src/mongo/s/query/cluster_client_cursor_params.h
index 0efec32f93a..e73a6d5d9ab 100644
--- a/src/mongo/s/query/cluster_client_cursor_params.h
+++ b/src/mongo/s/query/cluster_client_cursor_params.h
@@ -33,15 +33,10 @@
 
 #include "mongo/bson/bsonobj.h"
 #include "mongo/db/namespace_string.h"
-#include "mongo/util/net/hostandport.h"
 
 namespace mongo {
 
 struct ClusterClientCursorParams {
-    // When mongos has to do a merge in order to return results to the client in the correct sort
-    // order, it requests a sortKey meta-projection using this field name.
-    static const char kSortKeyField[];
-
     /**
      * Contains any CCC parameters that are specified per-remote node.
      */
diff --git a/src/mongo/s/query/cluster_find.cpp b/src/mongo/s/query/cluster_find.cpp
index b47c04b5453..73d41cfc3be 100644
--- a/src/mongo/s/query/cluster_find.cpp
+++ b/src/mongo/s/query/cluster_find.cpp
@@ -55,9 +55,6 @@ namespace mongo {
 
 namespace {
 
-static const BSONObj kSortKeyMetaProjection = BSON("$meta"
-                                                   << "sortKey");
-
 /**
  * Given the LiteParsedQuery 'lpq' being executed by mongos, returns a copy of the query which is
  * suitable for forwarding to the targeted hosts.
@@ -75,18 +72,9 @@ std::unique_ptr<LiteParsedQuery> transformQueryForShards(const LiteParsedQuery&
         newNToReturn = *lpq.getNToReturn() + lpq.getSkip().value_or(0);
     }
 
-    // If there is a sort, we send a sortKey meta-projection to the remote node.
-    BSONObj newProjection = lpq.getProj();
-    if (!lpq.getSort().isEmpty()) {
-        BSONObjBuilder projectionBuilder;
-        projectionBuilder.appendElements(lpq.getProj());
-        projectionBuilder.append(ClusterClientCursorParams::kSortKeyField, kSortKeyMetaProjection);
-        newProjection = projectionBuilder.obj();
-    }
-
     return LiteParsedQuery::makeAsFindCmd(lpq.nss(),
                                           lpq.getFilter(),
-                                          newProjection,
+                                          lpq.getProj(),
                                           lpq.getSort(),
                                           lpq.getHint(),
                                           boost::none,  // Don't forward skip.
@@ -145,7 +133,7 @@ StatusWith<CursorId> runQueryWithoutRetrying(OperationContext* txn,
     // sort on mongos. Including a $natural anywhere in the sort spec results in the whole sort
     // being considered a hint to use a collection scan.
     if (!query.getParsed().getSort().hasField("$natural")) {
-        params.sort = FindCommon::transformSortSpec(query.getParsed().getSort());
+        params.sort = query.getParsed().getSort();
     }
 
     // Tailable cursors can't have a sort, which should have already been validated.
@@ -239,14 +227,6 @@ StatusWith<CursorId> ClusterFind::runQuery(OperationContext* txn,
                                            std::vector<BSONObj>* results) {
     invariant(results);
 
-    // Projection on the reserved sort key field is illegal in mongos.
-    if (query.getParsed().getProj().hasField(ClusterClientCursorParams::kSortKeyField)) {
-        return {ErrorCodes::BadValue,
-                str::stream() << "Projection contains illegal field '"
-                              << ClusterClientCursorParams::kSortKeyField
-                              << "': " << query.getParsed().getProj()};
-    }
-
     auto dbConfig = grid.catalogCache()->getDatabase(txn, query.nss().db().toString());
     if (dbConfig.getStatus() == ErrorCodes::DatabaseNotFound) {
         // If the database doesn't exist, we successfully return an empty result set without
diff --git a/src/mongo/s/query/router_stage_remove_sortkey.cpp b/src/mongo/s/query/router_stage_remove_sortkey.cpp
deleted file mode 100644
index 7fa343f44c1..00000000000
--- a/src/mongo/s/query/router_stage_remove_sortkey.cpp
+++ /dev/null
@@ -1,64 +0,0 @@
-/**
- *    Copyright (C) 2015 MongoDB Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    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
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    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 GNU Affero General 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.
- */
-
-#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kQuery
-
-#include "mongo/platform/basic.h"
-
-#include "mongo/s/query/router_stage_remove_sortkey.h"
-
-#include "mongo/bson/bsonobjbuilder.h"
-#include "mongo/s/query/cluster_client_cursor_params.h"
-#include "mongo/util/mongoutils/str.h"
-
-namespace mongo {
-
-RouterStageRemoveSortKey::RouterStageRemoveSortKey(std::unique_ptr<RouterExecStage> child)
-    : RouterExecStage(std::move(child)) {}
-
-StatusWith<boost::optional<BSONObj>> RouterStageRemoveSortKey::next() {
-    auto childResult = getChildStage()->next();
-    if (!childResult.isOK() || !childResult.getValue()) {
-        return childResult;
-    }
-
-    BSONObjBuilder builder;
-    for (BSONElement elt : *childResult.getValue()) {
-        if (!str::equals(elt.fieldName(), ClusterClientCursorParams::kSortKeyField)) {
-            builder.append(elt);
-        }
-    }
-
-    return {builder.obj()};
-}
-
-void RouterStageRemoveSortKey::kill() {
-    getChildStage()->kill();
-}
-
-}  // namespace mongo
diff --git a/src/mongo/s/query/router_stage_remove_sortkey.h b/src/mongo/s/query/router_stage_remove_sortkey.h
deleted file mode 100644
index c376226f23f..00000000000
--- a/src/mongo/s/query/router_stage_remove_sortkey.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/**
- *    Copyright (C) 2015 MongoDB Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    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
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    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 GNU Affero General 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.
- */
-
-#pragma once
-
-#include "mongo/s/query/router_exec_stage.h"
-
-namespace mongo {
-
-/**
- * Removes the sort key added to each document by mongod's sortKey meta-projection.
- *
- * Only needed if the query specifies a sort.
- */
-class RouterStageRemoveSortKey final : public RouterExecStage {
-public:
-    RouterStageRemoveSortKey(std::unique_ptr<RouterExecStage> child);
-
-    StatusWith<boost::optional<BSONObj>> next() final;
-
-    void kill() final;
-};
-
-}  // namespace mongo
diff --git a/src/mongo/s/query/router_stage_remove_sortkey_test.cpp b/src/mongo/s/query/router_stage_remove_sortkey_test.cpp
deleted file mode 100644
index 90a7a555b07..00000000000
--- a/src/mongo/s/query/router_stage_remove_sortkey_test.cpp
+++ /dev/null
@@ -1,127 +0,0 @@
-/**
- *    Copyright 2015 MongoDB Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    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
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    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 GNU Affero General 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/s/query/router_stage_remove_sortkey.h"
-
-#include "mongo/bson/bsonobj.h"
-#include "mongo/bson/bsonobjbuilder.h"
-#include "mongo/s/query/router_stage_mock.h"
-#include "mongo/stdx/memory.h"
-#include "mongo/unittest/unittest.h"
-
-namespace mongo {
-
-namespace {
-
-TEST(RouterStageRemoveSortKeyTest, RemovesSortKey) {
-    auto mockStage = stdx::make_unique<RouterStageMock>();
-    mockStage->queueResult(BSON("a" << 4 << "$sortKey" << 1 << "b" << 3));
-    mockStage->queueResult(BSON("$sortKey" << BSON("" << 3) << "c" << BSON("d"
-                                                                           << "foo")));
-    mockStage->queueResult(BSON("a" << 3));
-    mockStage->queueResult(BSONObj());
-
-    auto sortKeyStage = stdx::make_unique<RouterStageRemoveSortKey>(std::move(mockStage));
-
-    auto firstResult = sortKeyStage->next();
-    ASSERT_OK(firstResult.getStatus());
-    ASSERT(firstResult.getValue());
-    ASSERT_EQ(*firstResult.getValue(), BSON("a" << 4 << "b" << 3));
-
-    auto secondResult = sortKeyStage->next();
-    ASSERT_OK(secondResult.getStatus());
-    ASSERT(secondResult.getValue());
-    ASSERT_EQ(*secondResult.getValue(),
-              BSON("c" << BSON("d"
-                               << "foo")));
-
-    auto thirdResult = sortKeyStage->next();
-    ASSERT_OK(thirdResult.getStatus());
-    ASSERT(thirdResult.getValue());
-    ASSERT_EQ(*thirdResult.getValue(), BSON("a" << 3));
-
-    auto fourthResult = sortKeyStage->next();
-    ASSERT_OK(fourthResult.getStatus());
-    ASSERT(fourthResult.getValue());
-    ASSERT_EQ(*fourthResult.getValue(), BSONObj());
-
-    auto fifthResult = sortKeyStage->next();
-    ASSERT_OK(fifthResult.getStatus());
-    ASSERT(!fifthResult.getValue());
-}
-
-TEST(RouterStageRemoveSortKeyTest, PropagatesError) {
-    auto mockStage = stdx::make_unique<RouterStageMock>();
-    mockStage->queueResult(BSON("$sortKey" << 1));
-    mockStage->queueError(Status(ErrorCodes::BadValue, "bad thing happened"));
-
-    auto sortKeyStage = stdx::make_unique<RouterStageRemoveSortKey>(std::move(mockStage));
-
-    auto firstResult = sortKeyStage->next();
-    ASSERT_OK(firstResult.getStatus());
-    ASSERT(firstResult.getValue());
-    ASSERT_EQ(*firstResult.getValue(), BSONObj());
-
-    auto secondResult = sortKeyStage->next();
-    ASSERT_NOT_OK(secondResult.getStatus());
-    ASSERT_EQ(secondResult.getStatus(), ErrorCodes::BadValue);
-    ASSERT_EQ(secondResult.getStatus().reason(), "bad thing happened");
-}
-
-TEST(RouterStageRemoveSortKeyTest, ToleratesMidStreamEOF) {
-    auto mockStage = stdx::make_unique<RouterStageMock>();
-    mockStage->queueResult(BSON("a" << 1 << "$sortKey" << 1 << "b" << 1));
-    mockStage->queueEOF();
-    mockStage->queueResult(BSON("a" << 2 << "$sortKey" << 1 << "b" << 2));
-
-    auto sortKeyStage = stdx::make_unique<RouterStageRemoveSortKey>(std::move(mockStage));
-
-    auto firstResult = sortKeyStage->next();
-    ASSERT_OK(firstResult.getStatus());
-    ASSERT(firstResult.getValue());
-    ASSERT_EQ(*firstResult.getValue(), BSON("a" << 1 << "b" << 1));
-
-    auto secondResult = sortKeyStage->next();
-    ASSERT_OK(secondResult.getStatus());
-    ASSERT(!secondResult.getValue());
-
-    auto thirdResult = sortKeyStage->next();
-    ASSERT_OK(thirdResult.getStatus());
-    ASSERT(thirdResult.getValue());
-    ASSERT_EQ(*thirdResult.getValue(), BSON("a" << 2 << "b" << 2));
-
-    auto fourthResult = sortKeyStage->next();
-    ASSERT_OK(fourthResult.getStatus());
-    ASSERT(!fourthResult.getValue());
-}
-
-}  // namespace
-
-}  // namespace mongo