SERVER-42589 Made the wall field in oplog_entry.idl a required field

34 files changed, 368 insertions, 360 deletions

diff --git a/src/mongo/db/op_observer_impl.cpp b/src/mongo/db/op_observer_impl.cpp
index 9be2ec5c89b..4ba8d17eea1 100644
--- a/src/mongo/db/op_observer_impl.cpp
+++ b/src/mongo/db/op_observer_impl.cpp
@@ -186,7 +186,7 @@ OpTimeBundle replLogUpdate(OperationContext* opCtx, const OplogUpdateEntryArgs&
     // oplogLink could have been changed to include pre/postImageOpTime by the previous no-op write.
     repl::appendRetryableWriteInfo(opCtx, &oplogEntry, &oplogLink, args.updateArgs.stmtId);
     opTimes.writeOpTime = logOperation(opCtx, &oplogEntry);
-    opTimes.wallClockTime = oplogEntry.getWallClockTime().get();
+    opTimes.wallClockTime = oplogEntry.getWallClockTime();
     return opTimes;
 }
 
@@ -223,7 +223,7 @@ OpTimeBundle replLogDelete(OperationContext* opCtx,
     // oplogLink could have been changed to include preImageOpTime by the previous no-op write.
     repl::appendRetryableWriteInfo(opCtx, &oplogEntry, &oplogLink, stmtId);
     opTimes.writeOpTime = logOperation(opCtx, &oplogEntry);
-    opTimes.wallClockTime = oplogEntry.getWallClockTime().get();
+    opTimes.wallClockTime = oplogEntry.getWallClockTime();
     return opTimes;
 }
 
@@ -808,7 +808,7 @@ OpTimeBundle logApplyOpsForTransaction(OperationContext* opCtx,
     try {
         OpTimeBundle times;
         times.writeOpTime = logOperation(opCtx, oplogEntry);
-        times.wallClockTime = oplogEntry->getWallClockTime().get();
+        times.wallClockTime = oplogEntry->getWallClockTime();
         if (updateTxnTable) {
             SessionTxnRecord sessionTxnRecord;
             sessionTxnRecord.setLastWriteOpTime(times.writeOpTime);
@@ -971,7 +971,7 @@ void logCommitOrAbortForPreparedTransaction(OperationContext* opCtx,
 
             SessionTxnRecord sessionTxnRecord;
             sessionTxnRecord.setLastWriteOpTime(oplogOpTime);
-            sessionTxnRecord.setLastWriteDate(oplogEntry->getWallClockTime().get());
+            sessionTxnRecord.setLastWriteDate(oplogEntry->getWallClockTime());
             sessionTxnRecord.setState(durableState);
             onWriteOpCompleted(opCtx, {}, sessionTxnRecord);
             wuow.commit();
diff --git a/src/mongo/db/ops/write_ops_retryability_test.cpp b/src/mongo/db/ops/write_ops_retryability_test.cpp
index 550744fa95c..2956efeb7cf 100644
--- a/src/mongo/db/ops/write_ops_retryability_test.cpp
+++ b/src/mongo/db/ops/write_ops_retryability_test.cpp
@@ -70,7 +70,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
                             o2Field,                          // o2
                             {},                               // sessionInfo
                             boost::none,                      // upsert
-                            boost::none,                      // wall clock time
+                            Date_t(),                         // wall clock time
                             boost::none,                      // statement id
                             boost::none,       // optime of previous write within same transaction
                             preImageOpTime,    // pre-image optime
@@ -83,7 +83,8 @@ TEST_F(WriteOpsRetryability, ParseOplogEntryForUpdate) {
                   << "u"
                   << "ns"
                   << "a.b"
-                  << "o" << BSON("_id" << 1 << "x" << 5) << "o2" << BSON("_id" << 1))));
+                  << "wall" << Date_t() << "o" << BSON("_id" << 1 << "x" << 5) << "o2"
+                  << BSON("_id" << 1))));
 
     auto res = parseOplogEntryForUpdate(entry);
 
@@ -112,12 +113,12 @@ TEST_F(WriteOpsRetryability, ParseOplogEntryForNestedUpdate) {
 }
 
 TEST_F(WriteOpsRetryability, ParseOplogEntryForUpsert) {
-    const auto entry =
-        assertGet(repl::OplogEntry::parse(BSON("ts" << Timestamp(50, 10) << "t" << 1LL << "op"
-                                                    << "i"
-                                                    << "ns"
-                                                    << "a.b"
-                                                    << "o" << BSON("_id" << 1 << "x" << 5))));
+    const auto entry = assertGet(repl::OplogEntry::parse(
+        BSON("ts" << Timestamp(50, 10) << "t" << 1LL << "op"
+                  << "i"
+                  << "ns"
+                  << "a.b"
+                  << "wall" << Date_t() << "o" << BSON("_id" << 1 << "x" << 5))));
 
     auto res = parseOplogEntryForUpdate(entry);
 
diff --git a/src/mongo/db/pipeline/document_source_change_stream_test.cpp b/src/mongo/db/pipeline/document_source_change_stream_test.cpp
index acc9d82e1f8..e9248465431 100644
--- a/src/mongo/db/pipeline/document_source_change_stream_test.cpp
+++ b/src/mongo/db/pipeline/document_source_change_stream_test.cpp
@@ -346,7 +346,7 @@ public:
                                 object2,                            // o2
                                 sessionInfo,                        // sessionInfo
                                 boost::none,                        // upsert
-                                boost::none,                        // wall clock time
+                                Date_t(),                           // wall clock time
                                 boost::none,                        // statement id
                                 prevOpTime,    // optime of previous write within same transaction
                                 boost::none,   // pre-image optime
@@ -1030,7 +1030,7 @@ TEST_F(ChangeStreamStageTest, CommitCommandReturnsOperationsFromPreparedTransact
                          boost::none,                      // o2
                          sessionInfo,                      // sessionInfo
                          boost::none,                      // upsert
-                         boost::none,                      // wall clock time
+                         Date_t(),                         // wall clock time
                          boost::none,                      // statement id
                          applyOpsOpTime,  // optime of previous write within same transaction
                          boost::none,     // pre-image optime
@@ -1227,7 +1227,7 @@ TEST_F(ChangeStreamStageTest, PreparedTransactionWithMultipleOplogEntries) {
                          boost::none,                      // o2
                          sessionInfo,                      // sessionInfo
                          boost::none,                      // upsert
-                         boost::none,                      // wall clock time
+                         Date_t(),                         // wall clock time
                          boost::none,                      // statement id
                          applyOpsOpTime2,  // optime of previous write within same transaction
                          boost::none,      // pre-image optime
diff --git a/src/mongo/db/repl/abstract_oplog_fetcher_test_fixture.cpp b/src/mongo/db/repl/abstract_oplog_fetcher_test_fixture.cpp
index 882cf5f4fa8..9f748b283c5 100644
--- a/src/mongo/db/repl/abstract_oplog_fetcher_test_fixture.cpp
+++ b/src/mongo/db/repl/abstract_oplog_fetcher_test_fixture.cpp
@@ -58,7 +58,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
                             boost::none,                      // o2
                             {},                               // sessionInfo
                             boost::none,                      // upsert
-                            boost::none,                      // wall clock time
+                            Date_t(),                         // wall clock time
                             boost::none,                      // statement id
                             boost::none,   // optime of previous write within same transaction
                             boost::none,   // pre-image optime
diff --git a/src/mongo/db/repl/apply_ops.cpp b/src/mongo/db/repl/apply_ops.cpp
index 49f8aab83ec..1e947868a65 100644
--- a/src/mongo/db/repl/apply_ops.cpp
+++ b/src/mongo/db/repl/apply_ops.cpp
@@ -162,9 +162,16 @@ Status _applyOps(OperationContext* opCtx,
 
             BSONObjBuilder builder;
             builder.appendElements(opObj);
+
+            // If required fields are not present in the BSONObj for an applyOps entry, create these
+            // fields and populate them with dummy values before parsing the BSONObj as an oplog
+            // entry.
             if (!builder.hasField(OplogEntry::kTimestampFieldName)) {
                 builder.append(OplogEntry::kTimestampFieldName, Timestamp());
             }
+            if (!builder.hasField(OplogEntry::kWallClockTimeFieldName)) {
+                builder.append(OplogEntry::kWallClockTimeFieldName, Date_t());
+            }
             // Reject malformed operations in an atomic applyOps.
             auto entry = OplogEntry::parse(builder.done());
             if (!entry.isOK()) {
@@ -212,6 +219,9 @@ Status _applyOps(OperationContext* opCtx,
                         if (!builder.hasField(OplogEntry::kHashFieldName)) {
                             builder.append(OplogEntry::kHashFieldName, 0LL);
                         }
+                        if (!builder.hasField(OplogEntry::kWallClockTimeFieldName)) {
+                            builder.append(OplogEntry::kWallClockTimeFieldName, Date_t());
+                        }
                         auto entry = uassertStatusOK(OplogEntry::parse(builder.done()));
                         if (*opType == 'c') {
                             invariant(opCtx->lockState()->isW());
diff --git a/src/mongo/db/repl/apply_ops_test.cpp b/src/mongo/db/repl/apply_ops_test.cpp
index eaa21394384..b5ddfadcd0f 100644
--- a/src/mongo/db/repl/apply_ops_test.cpp
+++ b/src/mongo/db/repl/apply_ops_test.cpp
@@ -346,7 +346,7 @@ OplogEntry makeOplogEntry(OpTypeEnum opType, const BSONObj& oField) {
                       boost::none,                 // o2
                       {},                          // sessionInfo
                       boost::none,                 // upsert
-                      boost::none,                 // wall clock time
+                      Date_t(),                    // wall clock time
                       boost::none,                 // statement id
                       boost::none,   // optime of previous write within same transaction
                       boost::none,   // pre-image optime
diff --git a/src/mongo/db/repl/idempotency_test_fixture.cpp b/src/mongo/db/repl/idempotency_test_fixture.cpp
index c7f77c967d5..6e609c9b6ae 100644
--- a/src/mongo/db/repl/idempotency_test_fixture.cpp
+++ b/src/mongo/db/repl/idempotency_test_fixture.cpp
@@ -74,7 +74,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
                                 BSONObj object,
                                 boost::optional<BSONObj> object2 = boost::none,
                                 OperationSessionInfo sessionInfo = {},
-                                boost::optional<Date_t> wallClockTime = boost::none,
+                                Date_t wallClockTime = Date_t(),
                                 boost::optional<StmtId> stmtId = boost::none,
                                 boost::optional<UUID> uuid = boost::none,
                                 boost::optional<OpTime> prevOpTime = boost::none) {
@@ -215,7 +215,7 @@ OplogEntry makeCommandOplogEntry(OpTime opTime,
                           command,
                           boost::none /* o2 */,
                           {} /* sessionInfo */,
-                          boost::none /* wallClockTime*/,
+                          Date_t() /* wallClockTime*/,
                           boost::none /* stmtId */,
                           uuid);
 }
diff --git a/src/mongo/db/repl/initial_syncer.cpp b/src/mongo/db/repl/initial_syncer.cpp
index 9843aa7b2ea..dc121c9072c 100644
--- a/src/mongo/db/repl/initial_syncer.cpp
+++ b/src/mongo/db/repl/initial_syncer.cpp
@@ -1182,8 +1182,7 @@ void InitialSyncer::_getNextApplierBatchCallback(
             return _oplogApplier->multiApply(opCtx, std::move(ops));
         };
         OpTime lastApplied = ops.back().getOpTime();
-        invariant(ops.back().getWallClockTime());
-        Date_t lastAppliedWall = ops.back().getWallClockTime().get();
+        Date_t lastAppliedWall = ops.back().getWallClockTime();
 
         auto numApplied = ops.size();
         MultiApplier::CallbackFn onCompletionFn = [=](const Status& s) {
diff --git a/src/mongo/db/repl/initial_syncer_test.cpp b/src/mongo/db/repl/initial_syncer_test.cpp
index b9eb16070bc..55f4b1074bf 100644
--- a/src/mongo/db/repl/initial_syncer_test.cpp
+++ b/src/mongo/db/repl/initial_syncer_test.cpp
@@ -1888,7 +1888,7 @@ TEST_F(InitialSyncerTest,
     ASSERT_OK(_lastApplied.getStatus());
     auto dummyEntry = makeOplogEntry(1);
     ASSERT_EQUALS(dummyEntry.getOpTime(), _lastApplied.getValue().opTime);
-    ASSERT_EQUALS(dummyEntry.getWallClockTime().get(), _lastApplied.getValue().wallTime);
+    ASSERT_EQUALS(dummyEntry.getWallClockTime(), _lastApplied.getValue().wallTime);
 }
 
 TEST_F(
@@ -1954,7 +1954,7 @@ TEST_F(
     ASSERT_OK(_lastApplied.getStatus());
     auto dummyEntry = makeOplogEntry(3);
     ASSERT_EQUALS(dummyEntry.getOpTime(), _lastApplied.getValue().opTime);
-    ASSERT_EQUALS(dummyEntry.getWallClockTime().get(), _lastApplied.getValue().wallTime);
+    ASSERT_EQUALS(dummyEntry.getWallClockTime(), _lastApplied.getValue().wallTime);
 }
 
 TEST_F(
@@ -3222,7 +3222,7 @@ TEST_F(InitialSyncerTest, LastOpTimeShouldBeSetEvenIfNoOperationsAreAppliedAfter
     initialSyncer->join();
     ASSERT_OK(_lastApplied.getStatus());
     ASSERT_EQUALS(oplogEntry.getOpTime(), _lastApplied.getValue().opTime);
-    ASSERT_EQUALS(oplogEntry.getWallClockTime().get(), _lastApplied.getValue().wallTime);
+    ASSERT_EQUALS(oplogEntry.getWallClockTime(), _lastApplied.getValue().wallTime);
     ASSERT_FALSE(_replicationProcess->getConsistencyMarkers()->getInitialSyncFlag(opCtx.get()));
 }
 
@@ -3823,7 +3823,7 @@ void InitialSyncerTest::doSuccessfulInitialSyncWithOneBatch() {
     serverGlobalParams.featureCompatibility.reset();
     ASSERT_OK(_lastApplied.getStatus());
     ASSERT_EQUALS(lastOp.getOpTime(), _lastApplied.getValue().opTime);
-    ASSERT_EQUALS(lastOp.getWallClockTime().get(), _lastApplied.getValue().wallTime);
+    ASSERT_EQUALS(lastOp.getWallClockTime(), _lastApplied.getValue().wallTime);
 
     ASSERT_EQUALS(lastOp.getOpTime().getTimestamp(), _storageInterface->getInitialDataTimestamp());
 }
@@ -3945,7 +3945,7 @@ TEST_F(InitialSyncerTest,
     initialSyncer->join();
     ASSERT_OK(_lastApplied.getStatus());
     ASSERT_EQUALS(lastOp.getOpTime(), _lastApplied.getValue().opTime);
-    ASSERT_EQUALS(lastOp.getWallClockTime().get(), _lastApplied.getValue().wallTime);
+    ASSERT_EQUALS(lastOp.getWallClockTime(), _lastApplied.getValue().wallTime);
 }
 
 TEST_F(InitialSyncerTest,
@@ -4270,7 +4270,7 @@ TEST_F(InitialSyncerTest, GetInitialSyncProgressReturnsCorrectProgress) {
     ASSERT_OK(_lastApplied.getStatus());
     auto dummyEntry = makeOplogEntry(7);
     ASSERT_EQUALS(dummyEntry.getOpTime(), _lastApplied.getValue().opTime);
-    ASSERT_EQUALS(dummyEntry.getWallClockTime().get(), _lastApplied.getValue().wallTime);
+    ASSERT_EQUALS(dummyEntry.getWallClockTime(), _lastApplied.getValue().wallTime);
 
     progress = initialSyncer->getInitialSyncProgress();
     log() << "Progress at end: " << progress;
diff --git a/src/mongo/db/repl/multiapplier_test.cpp b/src/mongo/db/repl/multiapplier_test.cpp
index 0dc922945f6..663f85db19e 100644
--- a/src/mongo/db/repl/multiapplier_test.cpp
+++ b/src/mongo/db/repl/multiapplier_test.cpp
@@ -77,7 +77,7 @@ OplogEntry makeOplogEntry(int ts) {
                       boost::none,                  // o2
                       {},                           // sessionInfo
                       boost::none,                  // upsert
-                      boost::none,                  // wall clock time
+                      Date_t(),                     // wall clock time
                       boost::none,                  // statement id
                       boost::none,   // optime of previous write within same transaction
                       boost::none,   // pre-image optime
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index 5bdbe14843f..64aed7ab370 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -405,7 +405,6 @@ OpTime logOp(OperationContext* opCtx, MutableOplogEntry* oplogEntry) {
 
     auto oplog = oplogInfo->getCollection();
     auto wallClockTime = oplogEntry->getWallClockTime();
-    invariant(wallClockTime);
 
     auto bsonOplogEntry = oplogEntry->toBSON();
     // The storage engine will assign the RecordId based on the "ts" field of the oplog entry, see
@@ -413,7 +412,7 @@ OpTime logOp(OperationContext* opCtx, MutableOplogEntry* oplogEntry) {
     std::vector<Record> records{
         {RecordId(), RecordData(bsonOplogEntry.objdata(), bsonOplogEntry.objsize())}};
     std::vector<Timestamp> timestamps{slot.getTimestamp()};
-    _logOpsInner(opCtx, oplogEntry->getNss(), &records, timestamps, oplog, slot, *wallClockTime);
+    _logOpsInner(opCtx, oplogEntry->getNss(), &records, timestamps, oplog, slot, wallClockTime);
     wuow.commit();
     return slot;
 }
@@ -491,8 +490,7 @@ std::vector<OpTime> logInsertOps(OperationContext* opCtx,
     invariant(!lastOpTime.isNull());
     auto oplog = oplogInfo->getCollection();
     auto wallClockTime = oplogEntryTemplate->getWallClockTime();
-    invariant(wallClockTime);
-    _logOpsInner(opCtx, nss, &records, timestamps, oplog, lastOpTime, *wallClockTime);
+    _logOpsInner(opCtx, nss, &records, timestamps, oplog, lastOpTime, wallClockTime);
     wuow.commit();
     return opTimes;
 }
diff --git a/src/mongo/db/repl/oplog_entry.cpp b/src/mongo/db/repl/oplog_entry.cpp
index f41558f2e4c..4da5afdc4dc 100644
--- a/src/mongo/db/repl/oplog_entry.cpp
+++ b/src/mongo/db/repl/oplog_entry.cpp
@@ -100,7 +100,7 @@ BSONObj makeOplogEntryDoc(OpTime opTime,
                           const boost::optional<BSONObj>& o2Field,
                           const OperationSessionInfo& sessionInfo,
                           const boost::optional<bool>& isUpsert,
-                          const boost::optional<mongo::Date_t>& wallClockTime,
+                          const mongo::Date_t& wallClockTime,
                           const boost::optional<StmtId>& statementId,
                           const boost::optional<OpTime>& prevWriteOpTimeInTransaction,
                           const boost::optional<OpTime>& preImageOpTime,
@@ -112,6 +112,7 @@ BSONObj makeOplogEntryDoc(OpTime opTime,
     builder.append(OplogEntryBase::kVersionFieldName, version);
     builder.append(OplogEntryBase::kOpTypeFieldName, OpType_serializer(opType));
     builder.append(OplogEntryBase::kNssFieldName, nss.toString());
+    builder.append(OplogEntryBase::kWallClockTimeFieldName, wallClockTime);
     if (hash) {
         builder.append(OplogEntryBase::kHashFieldName, hash.get());
     }
@@ -129,9 +130,6 @@ BSONObj makeOplogEntryDoc(OpTime opTime,
         invariant(o2Field);
         builder.append(OplogEntryBase::kUpsertFieldName, isUpsert.get());
     }
-    if (wallClockTime) {
-        builder.append(OplogEntryBase::kWallClockTimeFieldName, wallClockTime.get());
-    }
     if (statementId) {
         builder.append(OplogEntryBase::kStatementIdFieldName, statementId.get());
     }
@@ -251,7 +249,7 @@ OplogEntry::OplogEntry(OpTime opTime,
                        const boost::optional<BSONObj>& o2Field,
                        const OperationSessionInfo& sessionInfo,
                        const boost::optional<bool>& isUpsert,
-                       const boost::optional<mongo::Date_t>& wallClockTime,
+                       const mongo::Date_t& wallClockTime,
                        const boost::optional<StmtId>& statementId,
                        const boost::optional<OpTime>& prevWriteOpTimeInTransaction,
                        const boost::optional<OpTime>& preImageOpTime,
diff --git a/src/mongo/db/repl/oplog_entry.h b/src/mongo/db/repl/oplog_entry.h
index 5ae170a8730..190de25a9cc 100644
--- a/src/mongo/db/repl/oplog_entry.h
+++ b/src/mongo/db/repl/oplog_entry.h
@@ -236,7 +236,7 @@ public:
                const boost::optional<BSONObj>& o2Field,
                const OperationSessionInfo& sessionInfo,
                const boost::optional<bool>& isUpsert,
-               const boost::optional<mongo::Date_t>& wallClockTime,
+               const mongo::Date_t& wallClockTime,
                const boost::optional<StmtId>& statementId,
                const boost::optional<OpTime>& prevWriteOpTimeInTransaction,
                const boost::optional<OpTime>& preImageOpTime,
diff --git a/src/mongo/db/repl/oplog_entry.idl b/src/mongo/db/repl/oplog_entry.idl
index f242eec69d4..f2d1586914e 100644
--- a/src/mongo/db/repl/oplog_entry.idl
+++ b/src/mongo/db/repl/oplog_entry.idl
@@ -121,7 +121,6 @@ structs:
             wall:
                 cpp_name: wallClockTime
                 type: date
-                optional: true # Optional for older than 3.6 releases
                 description: "A wallclock time with MS resolution"
             stmtId:
                 cpp_name: statementId
diff --git a/src/mongo/db/repl/replication_recovery_test.cpp b/src/mongo/db/repl/replication_recovery_test.cpp
index ab77100a66e..ca678ebce17 100644
--- a/src/mongo/db/repl/replication_recovery_test.cpp
+++ b/src/mongo/db/repl/replication_recovery_test.cpp
@@ -227,7 +227,7 @@ repl::OplogEntry _makeOplogEntry(repl::OpTime opTime,
                                  BSONObj object,
                                  boost::optional<BSONObj> object2 = boost::none,
                                  OperationSessionInfo sessionInfo = {},
-                                 boost::optional<Date_t> wallTime = boost::none) {
+                                 Date_t wallTime = Date_t()) {
     return repl::OplogEntry(opTime,                           // optime
                             boost::none,                      // hash
                             opType,                           // opType
diff --git a/src/mongo/db/repl/roll_back_local_operations.h b/src/mongo/db/repl/roll_back_local_operations.h
index 986f1ebbf22..6c6e6c148ab 100644
--- a/src/mongo/db/repl/roll_back_local_operations.h
+++ b/src/mongo/db/repl/roll_back_local_operations.h
@@ -72,20 +72,20 @@ public:
             return _opTime;
         }
 
-        boost::optional<Date_t> getWallClockTime() const {
+        Date_t getWallClockTime() const {
             return _wallClockTime;
         }
 
-        boost::optional<Date_t> getFirstOpWallClockTimeAfterCommonPoint() {
+        Date_t getFirstOpWallClockTimeAfterCommonPoint() {
             return _firstWallClockTimeAfterCommonPoint;
         }
 
     private:
         RecordId _recordId;
         OpTime _opTime;
-        boost::optional<Date_t> _wallClockTime;
+        Date_t _wallClockTime;
         // The wall clock time of the first operation after the common point if it exists.
-        boost::optional<Date_t> _firstWallClockTimeAfterCommonPoint;
+        Date_t _firstWallClockTimeAfterCommonPoint;
     };
 
     /**
diff --git a/src/mongo/db/repl/roll_back_local_operations_test.cpp b/src/mongo/db/repl/roll_back_local_operations_test.cpp
index 67fff417d0a..6d4261938ea 100644
--- a/src/mongo/db/repl/roll_back_local_operations_test.cpp
+++ b/src/mongo/db/repl/roll_back_local_operations_test.cpp
@@ -46,32 +46,20 @@ namespace {
 using namespace mongo;
 using namespace mongo::repl;
 
-BSONObj makeOp(long long seconds, long long term = 1LL) {
+BSONObj makeOp(long long seconds, long long term = 1LL, long wallClockMillis = 0) {
     auto uuid = unittest::assertGet(UUID::parse("b4c66a44-c1ca-4d86-8d25-12e82fa2de5b"));
     return BSON("ts" << Timestamp(seconds, seconds) << "t" << term << "op"
                      << "n"
                      << "o" << BSONObj() << "ns"
                      << "roll_back_local_operations.test"
-                     << "ui" << uuid);
-}
-
-BSONObj makeOpWithWallClockTime(long count, long wallClockMillis, long long term = 1LL) {
-    auto uuid = unittest::assertGet(UUID::parse("b4c66a44-c1ca-4d86-8d25-12e82fa2de5b"));
-    return BSON("ts" << Timestamp(count, count) << "t" << term << "op"
-                     << "n"
-                     << "o" << BSONObj() << "ns"
-                     << "roll_back_local_operations.test"
                      << "ui" << uuid << "wall" << Date_t::fromMillisSinceEpoch(wallClockMillis));
-};
+}
 
 int recordId = 0;
-OplogInterfaceMock::Operation makeOpAndRecordId(long long seconds, long long term = 1LL) {
-    return std::make_pair(makeOp(seconds), RecordId(++recordId));
-}
-OplogInterfaceMock::Operation makeOpWithWallClockTimeAndRecordId(long long seconds,
-                                                                 long wallClockMillis,
-                                                                 long long term = 1LL) {
-    return std::make_pair(makeOpWithWallClockTime(seconds, wallClockMillis), RecordId(++recordId));
+OplogInterfaceMock::Operation makeOpAndRecordId(long long seconds,
+                                                long long term = 1LL,
+                                                long long wallClockMillis = 0) {
+    return std::make_pair(makeOp(seconds, term, wallClockMillis), RecordId(++recordId));
 }
 
 TEST(RollBackLocalOperationsTest, InvalidLocalOplogIterator) {
@@ -236,8 +224,8 @@ TEST(SyncRollBackLocalOperationsTest, RemoteOplogMissing) {
 }
 
 TEST(SyncRollBackLocalOperationsTest, RollbackTwoOperations) {
-    auto commonOperation = makeOpWithWallClockTimeAndRecordId(1, 1 * 5000);
-    auto firstOpAfterCommonPoint = makeOpWithWallClockTimeAndRecordId(2, 2 * 60 * 60 * 24 * 1000);
+    auto commonOperation = makeOpAndRecordId(1, 1LL, 1 * 5000);
+    auto firstOpAfterCommonPoint = makeOpAndRecordId(2, 1LL, 2 * 60 * 60 * 24 * 1000);
     OplogInterfaceMock::Operations localOperations({
         makeOpAndRecordId(3),
         firstOpAfterCommonPoint,
@@ -259,8 +247,8 @@ TEST(SyncRollBackLocalOperationsTest, RollbackTwoOperations) {
     ASSERT_BSONOBJ_EQ(commonOperation.first, i->first);
     auto firstOplogEntryAfterCommonPoint =
         uassertStatusOK(OplogEntry::parse(firstOpAfterCommonPoint.first));
-    ASSERT_EQUALS(*result.getValue().getFirstOpWallClockTimeAfterCommonPoint(),
-                  *firstOplogEntryAfterCommonPoint.getWallClockTime());
+    ASSERT_EQUALS(result.getValue().getFirstOpWallClockTimeAfterCommonPoint(),
+                  firstOplogEntryAfterCommonPoint.getWallClockTime());
     i++;
     ASSERT_TRUE(i == localOperations.cend());
 }
diff --git a/src/mongo/db/repl/rollback_impl.cpp b/src/mongo/db/repl/rollback_impl.cpp
index 3739e8039a0..1e450f9968b 100644
--- a/src/mongo/db/repl/rollback_impl.cpp
+++ b/src/mongo/db/repl/rollback_impl.cpp
@@ -970,42 +970,33 @@ Status RollbackImpl::_checkAgainstTimeLimit(
 
     _rollbackStats.lastLocalOptime = topOfOplog.getOpTime();
 
-    auto topOfOplogWallOpt = topOfOplog.getWallClockTime();
+    auto topOfOplogWallTime = topOfOplog.getWallClockTime();
     // We check the difference between the top of the oplog and the first oplog entry after the
     // common point when computing the rollback time limit.
-    auto firstOpWallClockTimeAfterCommonPointOpt =
+    auto firstOpWallClockTimeAfterCommonPoint =
         commonPoint.getFirstOpWallClockTimeAfterCommonPoint();
 
+    if (topOfOplogWallTime >= firstOpWallClockTimeAfterCommonPoint) {
 
-    // Only compute the difference if both the top of the oplog and the first oplog entry after the
-    // common point have wall clock times.
-    if (firstOpWallClockTimeAfterCommonPointOpt && topOfOplogWallOpt) {
-        auto topOfOplogWallTime = topOfOplogWallOpt.get();
-        auto firstOpWallClockTimeAfterCommonPoint = firstOpWallClockTimeAfterCommonPointOpt.get();
+        unsigned long long diff = durationCount<Seconds>(
+            Milliseconds(topOfOplogWallTime - firstOpWallClockTimeAfterCommonPoint));
 
-        if (topOfOplogWallTime >= firstOpWallClockTimeAfterCommonPoint) {
+        _rollbackStats.lastLocalWallClockTime = topOfOplogWallTime;
+        _rollbackStats.firstOpWallClockTimeAfterCommonPoint = firstOpWallClockTimeAfterCommonPoint;
 
-            unsigned long long diff = durationCount<Seconds>(
-                Milliseconds(topOfOplogWallTime - firstOpWallClockTimeAfterCommonPoint));
-
-            _rollbackStats.lastLocalWallClockTime = topOfOplogWallTime;
-            _rollbackStats.firstOpWallClockTimeAfterCommonPoint =
-                firstOpWallClockTimeAfterCommonPoint;
-
-            auto timeLimit = static_cast<unsigned long long>(gRollbackTimeLimitSecs.loadRelaxed());
-            if (diff > timeLimit) {
-                return Status(ErrorCodes::UnrecoverableRollbackError,
-                              str::stream() << "not willing to roll back more than " << timeLimit
-                                            << " seconds of data. Have: " << diff << " seconds.");
-            }
-
-        } else {
-            warning()
-                << "Wall clock times on oplog entries not monotonically increasing. This "
-                   "might indicate a backward clock skew. Time at first oplog after common point: "
-                << firstOpWallClockTimeAfterCommonPoint
-                << ". Time at top of oplog: " << topOfOplogWallTime;
+        auto timeLimit = static_cast<unsigned long long>(gRollbackTimeLimitSecs.loadRelaxed());
+        if (diff > timeLimit) {
+            return Status(ErrorCodes::UnrecoverableRollbackError,
+                          str::stream() << "not willing to roll back more than " << timeLimit
+                                        << " seconds of data. Have: " << diff << " seconds.");
         }
+
+    } else {
+        warning()
+            << "Wall clock times on oplog entries not monotonically increasing. This "
+               "might indicate a backward clock skew. Time at first oplog after common point: "
+            << firstOpWallClockTimeAfterCommonPoint
+            << ". Time at top of oplog: " << topOfOplogWallTime;
     }
 
     return Status::OK();
diff --git a/src/mongo/db/repl/rollback_impl_test.cpp b/src/mongo/db/repl/rollback_impl_test.cpp
index e3cb9c970c9..4d19ac681fc 100644
--- a/src/mongo/db/repl/rollback_impl_test.cpp
+++ b/src/mongo/db/repl/rollback_impl_test.cpp
@@ -69,21 +69,21 @@ std::string kGenericUUIDStr = "b4c66a44-c1ca-4d86-8d25-12e82fa2de5b";
 BSONObj makeInsertOplogEntry(long long time, BSONObj obj, StringData ns, UUID uuid) {
     return BSON("ts" << Timestamp(time, time) << "t" << time << "op"
                      << "i"
-                     << "o" << obj << "ns" << ns << "ui" << uuid);
+                     << "o" << obj << "ns" << ns << "ui" << uuid << "wall" << Date_t());
 }
 
 BSONObj makeUpdateOplogEntry(
     long long time, BSONObj query, BSONObj update, StringData ns, UUID uuid) {
     return BSON("ts" << Timestamp(time, time) << "t" << time << "op"
                      << "u"
-                     << "ns" << ns << "ui" << uuid << "o2" << query << "o"
-                     << BSON("$set" << update));
+                     << "ns" << ns << "ui" << uuid << "o2" << query << "o" << BSON("$set" << update)
+                     << "wall" << Date_t());
 }
 
 BSONObj makeDeleteOplogEntry(long long time, BSONObj id, StringData ns, UUID uuid) {
     return BSON("ts" << Timestamp(time, time) << "t" << time << "op"
                      << "d"
-                     << "ns" << ns << "ui" << uuid << "o" << id);
+                     << "ns" << ns << "ui" << uuid << "o" << id << "wall" << Date_t());
 }
 
 class RollbackImplForTest final : public RollbackImpl {
@@ -364,7 +364,8 @@ BSONObj makeOp(OpTime time) {
     auto kGenericUUID = unittest::assertGet(UUID::parse(kGenericUUIDStr));
     return BSON("ts" << time.getTimestamp() << "t" << time.getTerm() << "op"
                      << "n"
-                     << "o" << BSONObj() << "ns" << nss.ns() << "ui" << kGenericUUID);
+                     << "o" << BSONObj() << "ns" << nss.ns() << "ui" << kGenericUUID << "wall"
+                     << Date_t());
 }
 
 BSONObj makeOp(int count) {
@@ -929,10 +930,10 @@ TEST_F(RollbackImplTest, RollbackDoesNotWriteRollbackFilesIfNoInsertsOrUpdatesAf
     const auto uuid = UUID::gen();
     const auto nss = NamespaceString("db.coll");
     const auto coll = _initializeCollection(_opCtx.get(), uuid, nss);
-    const auto oplogEntry =
-        BSON("ts" << Timestamp(3, 3) << "t" << 3LL << "op"
-                  << "c"
-                  << "o" << BSON("create" << nss.coll()) << "ns" << nss.ns() << "ui" << uuid);
+    const auto oplogEntry = BSON("ts" << Timestamp(3, 3) << "t" << 3LL << "op"
+                                      << "c"
+                                      << "wall" << Date_t() << "o" << BSON("create" << nss.coll())
+                                      << "ns" << nss.ns() << "ui" << uuid);
     ASSERT_OK(_insertOplogEntry(oplogEntry));
 
     ASSERT_OK(_rollback->runRollback(_opCtx.get()));
@@ -1154,7 +1155,8 @@ TEST_F(RollbackImplTest, RollbackProperlySavesFilesWhenInsertsAndDropOfCollectio
     const auto oplogEntry =
         BSON("ts" << dropOpTime.getTimestamp() << "t" << dropOpTime.getTerm() << "op"
                   << "c"
-                  << "o" << BSON("drop" << nss.coll()) << "ns" << nss.ns() << "ui" << uuid);
+                  << "wall" << Date_t() << "o" << BSON("drop" << nss.coll()) << "ns" << nss.ns()
+                  << "ui" << uuid);
     ASSERT_OK(_insertOplogEntry(oplogEntry));
 
     ASSERT_OK(_rollback->runRollback(_opCtx.get()));
@@ -1179,10 +1181,10 @@ TEST_F(RollbackImplTest, RollbackProperlySavesFilesWhenCreateCollAndInsertsAreRo
     const auto nss = NamespaceString("db.people");
     const auto uuid = UUID::gen();
     const auto coll = _initializeCollection(_opCtx.get(), uuid, nss);
-    const auto oplogEntry =
-        BSON("ts" << Timestamp(3, 3) << "t" << 3LL << "op"
-                  << "c"
-                  << "o" << BSON("create" << nss.coll()) << "ns" << nss.ns() << "ui" << uuid);
+    const auto oplogEntry = BSON("ts" << Timestamp(3, 3) << "t" << 3LL << "op"
+                                      << "c"
+                                      << "wall" << Date_t() << "o" << BSON("create" << nss.coll())
+                                      << "ns" << nss.ns() << "ui" << uuid);
     ASSERT_OK(_insertOplogEntry(oplogEntry));
 
     // Insert documents into the collection.
@@ -1429,7 +1431,7 @@ RollbackImplTest::_setUpUnpreparedTransactionForCountTest(UUID collId) {
                                          boost::none,                // o2Field
                                          sessionInfo,                // sessionInfo
                                          boost::none,                // isUpsert
-                                         boost::none,                // wallClockTime
+                                         Date_t(),                   // wallClockTime
                                          boost::none,                // statementId
                                          OpTime(),                   // prevWriteOpTimeInTransaction
                                          boost::none,                // preImageOpTime
@@ -1454,7 +1456,7 @@ RollbackImplTest::_setUpUnpreparedTransactionForCountTest(UUID collId) {
                                         boost::none,                // o2Field
                                         sessionInfo,                // sessionInfo
                                         boost::none,                // isUpsert
-                                        boost::none,                // wallClockTime
+                                        Date_t(),                   // wallClockTime
                                         boost::none,                // statementId
                                         partialApplyOpsOpTime,      // prevWriteOpTimeInTransaction
                                         boost::none,                // preImageOpTime
@@ -1536,6 +1538,7 @@ public:
         collId.appendToBuilder(&bob, "ui");
         bob.append("ns", nss.ns());
         bob.append("o", doc);
+        bob.append("wall", Date_t());
         bob.append("lsid",
                    BSON("id" << sessionId << "uid"
                              << BSONBinData(std::string(32, 'x').data(), 32, BinDataGeneral)));
diff --git a/src/mongo/db/repl/rollback_test_fixture.cpp b/src/mongo/db/repl/rollback_test_fixture.cpp
index b5824819380..881a0b2c612 100644
--- a/src/mongo/db/repl/rollback_test_fixture.cpp
+++ b/src/mongo/db/repl/rollback_test_fixture.cpp
@@ -160,6 +160,7 @@ std::pair<BSONObj, RecordId> RollbackTest::makeCRUDOp(OpTypeEnum opType,
     if (o2) {
         bob.append("o2", *o2);
     }
+    bob.append("wall", Date_t());
 
     return std::make_pair(bob.obj(), RecordId(recordId));
 }
@@ -183,6 +184,7 @@ std::pair<BSONObj, RecordId> RollbackTest::makeCommandOp(Timestamp ts,
     if (o2) {
         bob.append("o2", *o2);
     }
+    bob.append("wall", Date_t());
 
     return std::make_pair(bob.obj(), RecordId(recordId));
 }
@@ -297,7 +299,7 @@ void RollbackResyncsCollectionOptionsTest::resyncCollectionOptionsTest(
                                   << "n"
                                   << "o" << BSONObj() << "ns"
                                   << "rollback_test.test"
-                                  << "ui" << commonOpUuid);
+                                  << "wall" << Date_t() << "ui" << commonOpUuid);
 
     auto commonOperation = std::make_pair(commonOpBson, RecordId(1));
 
diff --git a/src/mongo/db/repl/rs_rollback.cpp b/src/mongo/db/repl/rs_rollback.cpp
index d7f2382d120..911c822f9f7 100644
--- a/src/mongo/db/repl/rs_rollback.cpp
+++ b/src/mongo/db/repl/rs_rollback.cpp
@@ -234,11 +234,16 @@ Status rollback_internal::updateFixUpInfoFromLocalOplogEntry(OperationContext* o
     // and populate them with dummy values before parsing ourObj as an oplog entry.
     BSONObjBuilder bob;
     if (isNestedApplyOpsCommand) {
-        if (!ourObj.hasField("ts")) {
-            bob.appendTimestamp("ts");
+        if (!ourObj.hasField(OplogEntry::kTimestampFieldName)) {
+            bob.appendTimestamp(OplogEntry::kTimestampFieldName);
+        }
+        if (!ourObj.hasField(OplogEntry::kWallClockTimeFieldName)) {
+            bob.append(OplogEntry::kWallClockTimeFieldName, Date_t());
         }
     }
+
     bob.appendElements(ourObj);
+
     BSONObj fixedObj = bob.obj();
 
     // Parse the oplog entry.
diff --git a/src/mongo/db/repl/rs_rollback_test.cpp b/src/mongo/db/repl/rs_rollback_test.cpp
index 6408443af27..85d13299072 100644
--- a/src/mongo/db/repl/rs_rollback_test.cpp
+++ b/src/mongo/db/repl/rs_rollback_test.cpp
@@ -90,7 +90,7 @@ OplogInterfaceMock::Operation makeDropIndexOplogEntry(Collection* collection,
                   << "ui" << collection->uuid() << "ns"
                   << "test.$cmd"
                   << "o" << BSON("dropIndexes" << collection->ns().coll() << "index" << indexName)
-                  << "o2" << indexSpec),
+                  << "o2" << indexSpec << "wall" << Date_t()),
         RecordId(time));
 }
 
@@ -106,7 +106,8 @@ OplogInterfaceMock::Operation makeCreateIndexOplogEntry(Collection* collection,
                                     << "c"
                                     << "ns"
                                     << "test.$cmd"
-                                    << "ui" << collection->uuid() << "o" << indexSpec),
+                                    << "ui" << collection->uuid() << "o" << indexSpec << "wall"
+                                    << Date_t()),
                           RecordId(time));
 }
 
@@ -129,7 +130,7 @@ OplogInterfaceMock::Operation makeRenameCollectionOplogEntry(const NamespaceStri
     return std::make_pair(BSON("ts" << opTime.getTimestamp() << "t" << opTime.getTerm() << "op"
                                     << "c"
                                     << "ui" << collectionUUID << "ns" << renameFrom.ns() << "o"
-                                    << obj),
+                                    << obj << "wall" << Date_t()),
                           RecordId(opTime.getTimestamp().getSecs()));
 }
 
@@ -139,7 +140,7 @@ BSONObj makeOp(long long seconds) {
                      << "n"
                      << "o" << BSONObj() << "ns"
                      << "rs_rollback.test"
-                     << "ui" << uuid);
+                     << "ui" << uuid << "wall" << Date_t());
 }
 
 int recordId = 0;
@@ -273,12 +274,13 @@ int _testRollbackDelete(OperationContext* opCtx,
                         const BSONObj& documentAtSource,
                         const bool collectionAtSourceExists = true) {
     auto commonOperation = makeOpAndRecordId(1);
-    auto deleteOperation = std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
-                                                    << "d"
-                                                    << "ui" << uuid << "ns"
-                                                    << "test.t"
-                                                    << "o" << BSON("_id" << 0)),
-                                          RecordId(2));
+    auto deleteOperation =
+        std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
+                                 << "d"
+                                 << "ui" << uuid << "ns"
+                                 << "test.t"
+                                 << "o" << BSON("_id" << 0) << "wall" << Date_t()),
+                       RecordId(2));
     class RollbackSourceLocal : public RollbackSourceMock {
     public:
         RollbackSourceLocal(const BSONObj& documentAtSource,
@@ -397,12 +399,13 @@ TEST_F(RSRollbackTest, RollbackDeleteRestoreDocument) {
 TEST_F(RSRollbackTest, RollbackInsertDocumentWithNoId) {
     createOplog(_opCtx.get());
     auto commonOperation = makeOpAndRecordId(1);
-    auto insertDocumentOperation = std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
-                                                            << "i"
-                                                            << "ui" << UUID::gen() << "ns"
-                                                            << "test.t"
-                                                            << "o" << BSON("a" << 1)),
-                                                  RecordId(2));
+    auto insertDocumentOperation =
+        std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
+                                 << "i"
+                                 << "ui" << UUID::gen() << "ns"
+                                 << "test.t"
+                                 << "wall" << Date_t() << "o" << BSON("a" << 1)),
+                       RecordId(2));
     class RollbackSourceLocal : public RollbackSourceMock {
     public:
         RollbackSourceLocal(std::unique_ptr<OplogInterface> oplog)
@@ -740,15 +743,16 @@ TEST_F(RSRollbackTest, RollbackCreateIndexCommandMissingIndexName) {
                            << "t"
                            << "ns"
                            << "test.t"
-                           << "v" << static_cast<int>(kIndexVersion) << "key" << BSON("a" << 1));
-
-    auto createIndexOperation =
-        std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
-                                 << "c"
-                                 << "ns"
-                                 << "test.$cmd"
-                                 << "ui" << collection->uuid() << "o" << command),
-                       RecordId(2));
+                           << "wall" << Date_t() << "v" << static_cast<int>(kIndexVersion) << "key"
+                           << BSON("a" << 1));
+
+    auto createIndexOperation = std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
+                                                         << "c"
+                                                         << "ns"
+                                                         << "test.$cmd"
+                                                         << "wall" << Date_t() << "ui"
+                                                         << collection->uuid() << "o" << command),
+                                               RecordId(2));
     RollbackSourceMock rollbackSource(std::unique_ptr<OplogInterface>(new OplogInterfaceMock({
         commonOperation,
     })));
@@ -938,7 +942,7 @@ TEST_F(RSRollbackTest, RollbackUnknownCommand) {
                                                             << "c"
                                                             << "ui" << UUID::gen() << "ns"
                                                             << "test.t"
-                                                            << "o"
+                                                            << "wall" << Date_t() << "o"
                                                             << BSON("convertToCapped"
                                                                     << "t")),
                                                   RecordId(2));
@@ -972,7 +976,7 @@ TEST_F(RSRollbackTest, RollbackDropCollectionCommand) {
                                  << "c"
                                  << "ui" << coll->uuid() << "ns"
                                  << "test.t"
-                                 << "o"
+                                 << "wall" << Date_t() << "o"
                                  << BSON("drop"
                                          << "t")),
                        RecordId(2));
@@ -1294,7 +1298,7 @@ TEST_F(RSRollbackTest, RollbackDropCollectionThenRenameCollectionToDroppedCollec
                                  << "c"
                                  << "ui" << droppedCollectionUUID << "ns"
                                  << "test.x"
-                                 << "o"
+                                 << "wall" << Date_t() << "o"
                                  << BSON("drop"
                                          << "x")),
                        RecordId(2));
@@ -1367,7 +1371,7 @@ TEST_F(RSRollbackTest, RollbackRenameCollectionThenCreateNewCollectionWithOldNam
                                  << "c"
                                  << "ui" << createdCollectionUUID << "ns"
                                  << "test.x"
-                                 << "o"
+                                 << "wall" << Date_t() << "o"
                                  << BSON("create"
                                          << "x")),
                        RecordId(3));
@@ -1413,7 +1417,7 @@ TEST_F(RSRollbackTest, RollbackCollModCommandFailsIfRBIDChangesWhileSyncingColle
                                                      << "c"
                                                      << "ui" << coll->uuid() << "ns"
                                                      << "test.t"
-                                                     << "o"
+                                                     << "wall" << Date_t() << "o"
                                                      << BSON("collMod"
                                                              << "t"
                                                              << "validationLevel"
@@ -1451,12 +1455,13 @@ TEST_F(RSRollbackTest, RollbackDropDatabaseCommand) {
     createOplog(_opCtx.get());
     auto commonOperation = makeOpAndRecordId(1);
     // 'dropDatabase' operations are special and do not include a UUID field.
-    auto dropDatabaseOperation = std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
-                                                          << "c"
-                                                          << "ns"
-                                                          << "test.$cmd"
-                                                          << "o" << BSON("dropDatabase" << 1)),
-                                                RecordId(2));
+    auto dropDatabaseOperation =
+        std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
+                                 << "c"
+                                 << "ns"
+                                 << "test.$cmd"
+                                 << "wall" << Date_t() << "o" << BSON("dropDatabase" << 1)),
+                       RecordId(2));
     RollbackSourceMock rollbackSource(std::unique_ptr<OplogInterface>(new OplogInterfaceMock({
         commonOperation,
     })));
@@ -1474,7 +1479,8 @@ BSONObj makeApplyOpsOplogEntry(Timestamp ts, std::initializer_list<BSONObj> ops)
     entry << "ts" << ts << "op"
           << "c"
           << "ns"
-          << "admin";
+          << "admin"
+          << "wall" << Date_t();
     {
         BSONObjBuilder cmd(entry.subobjStart("o"));
         BSONArrayBuilder subops(entry.subarrayStart("applyOps"));
@@ -1529,41 +1535,41 @@ TEST_F(RSRollbackTest, RollbackApplyOpsCommand) {
                                  << "u"
                                  << "ui" << uuid << "ts" << Timestamp(1, 1) << "t" << 1LL << "ns"
                                  << "test.t"
-                                 << "o2" << BSON("_id" << 1) << "o"
+                                 << "o2" << BSON("_id" << 1) << "wall" << Date_t() << "o"
                                  << BSON("_id" << 1 << "v" << 2)),
                             BSON("op"
                                  << "u"
                                  << "ui" << uuid << "ts" << Timestamp(2, 1) << "t" << 1LL << "ns"
                                  << "test.t"
-                                 << "o2" << BSON("_id" << 2) << "o"
+                                 << "o2" << BSON("_id" << 2) << "wall" << Date_t() << "o"
                                  << BSON("_id" << 2 << "v" << 4)),
                             BSON("op"
                                  << "d"
                                  << "ui" << uuid << "ts" << Timestamp(3, 1) << "t" << 1LL << "ns"
                                  << "test.t"
-                                 << "o" << BSON("_id" << 3)),
+                                 << "wall" << Date_t() << "o" << BSON("_id" << 3)),
                             BSON("op"
                                  << "i"
                                  << "ui" << uuid << "ts" << Timestamp(4, 1) << "t" << 1LL << "ns"
                                  << "test.t"
-                                 << "o" << BSON("_id" << 4)),
+                                 << "wall" << Date_t() << "o" << BSON("_id" << 4)),
                             // applyOps internal oplog entries are not required
                             // to have a timestamp.
                             BSON("op"
                                  << "i"
                                  << "ui" << uuid << "ts" << Timestamp(4, 1) << "t" << 1LL << "ns"
                                  << "test.t"
-                                 << "o" << BSON("_id" << 4)),
+                                 << "wall" << Date_t() << "o" << BSON("_id" << 4)),
                             BSON("op"
                                  << "i"
                                  << "ui" << uuid << "t" << 1LL << "ns"
                                  << "test.t"
-                                 << "o" << BSON("_id" << 4)),
+                                 << "wall" << Date_t() << "o" << BSON("_id" << 4)),
                             BSON("op"
                                  << "i"
                                  << "ui" << uuid << "t" << 1LL << "ns"
                                  << "test.t"
-                                 << "o" << BSON("_id" << 4))}),
+                                 << "wall" << Date_t() << "o" << BSON("_id" << 4))}),
                        RecordId(2));
 
     class RollbackSourceLocal : public RollbackSourceMock {
@@ -1633,7 +1639,7 @@ TEST_F(RSRollbackTest, RollbackCreateCollectionCommand) {
                                                               << "c"
                                                               << "ui" << coll->uuid() << "ns"
                                                               << "test.t"
-                                                              << "o"
+                                                              << "wall" << Date_t() << "o"
                                                               << BSON("create"
                                                                       << "t")),
                                                     RecordId(2));
@@ -1862,7 +1868,7 @@ TEST(RSRollbackTest, LocalEntryWithoutNsIsFatal) {
                                       << "ui" << UUID::gen() << "ts" << Timestamp(1, 1) << "t"
                                       << 1LL << "ns"
                                       << "test.t"
-                                      << "o" << BSON("_id" << 1 << "a" << 1));
+                                      << "wall" << Date_t() << "o" << BSON("_id" << 1 << "a" << 1));
     FixUpInfo fui;
     ASSERT_OK(updateFixUpInfoFromLocalOplogEntry(
         nullptr /* opCtx */, OplogInterfaceMock(), fui, validOplogEntry, false));
@@ -1871,7 +1877,8 @@ TEST(RSRollbackTest, LocalEntryWithoutNsIsFatal) {
                                         << "ui" << UUID::gen() << "ts" << Timestamp(1, 1) << "t"
                                         << 1LL << "ns"
                                         << ""
-                                        << "o" << BSON("_id" << 1 << "a" << 1));
+                                        << "wall" << Date_t() << "o"
+                                        << BSON("_id" << 1 << "a" << 1));
     ASSERT_THROWS(updateFixUpInfoFromLocalOplogEntry(
                       nullptr /* opCtx */, OplogInterfaceMock(), fui, invalidOplogEntry, false),
                   RSFatalException);
@@ -1883,7 +1890,7 @@ TEST(RSRollbackTest, LocalEntryWithoutOIsFatal) {
                                       << "ui" << UUID::gen() << "ts" << Timestamp(1, 1) << "t"
                                       << 1LL << "ns"
                                       << "test.t"
-                                      << "o" << BSON("_id" << 1 << "a" << 1));
+                                      << "wall" << Date_t() << "o" << BSON("_id" << 1 << "a" << 1));
     FixUpInfo fui;
     ASSERT_OK(updateFixUpInfoFromLocalOplogEntry(
         nullptr /* opCtx */, OplogInterfaceMock(), fui, validOplogEntry, false));
@@ -1892,7 +1899,7 @@ TEST(RSRollbackTest, LocalEntryWithoutOIsFatal) {
                                         << "ui" << UUID::gen() << "ts" << Timestamp(1, 1) << "t"
                                         << 1LL << "ns"
                                         << "test.t"
-                                        << "o" << BSONObj());
+                                        << "wall" << Date_t() << "o" << BSONObj());
     ASSERT_THROWS(updateFixUpInfoFromLocalOplogEntry(
                       nullptr /* opCtx */, OplogInterfaceMock(), fui, invalidOplogEntry, false),
                   RSFatalException);
@@ -1904,7 +1911,8 @@ DEATH_TEST_F(RSRollbackTest, LocalUpdateEntryWithoutO2IsFatal, "Fatal Assertion"
                                         << "ui" << UUID::gen() << "ts" << Timestamp(1, 1) << "t"
                                         << 1LL << "ns"
                                         << "test.t"
-                                        << "o" << BSON("_id" << 1 << "a" << 1));
+                                        << "wall" << Date_t() << "o"
+                                        << BSON("_id" << 1 << "a" << 1));
     FixUpInfo fui;
     updateFixUpInfoFromLocalOplogEntry(
         nullptr /* opCtx */, OplogInterfaceMock(), fui, invalidOplogEntry, false)
@@ -1917,8 +1925,8 @@ TEST(RSRollbackTest, LocalUpdateEntryWithEmptyO2IsFatal) {
                                       << "ui" << UUID::gen() << "ts" << Timestamp(1, 1) << "t"
                                       << 1LL << "ns"
                                       << "test.t"
-                                      << "o" << BSON("_id" << 1 << "a" << 1) << "o2"
-                                      << BSON("_id" << 1));
+                                      << "wall" << Date_t() << "o" << BSON("_id" << 1 << "a" << 1)
+                                      << "o2" << BSON("_id" << 1));
     FixUpInfo fui;
     ASSERT_OK(updateFixUpInfoFromLocalOplogEntry(
         nullptr /* opCtx */, OplogInterfaceMock(), fui, validOplogEntry, false));
@@ -1927,8 +1935,8 @@ TEST(RSRollbackTest, LocalUpdateEntryWithEmptyO2IsFatal) {
                                         << "ui" << UUID::gen() << "ts" << Timestamp(1, 1) << "t"
                                         << 1LL << "ns"
                                         << "test.t"
-                                        << "o" << BSON("_id" << 1 << "a" << 1) << "o2"
-                                        << BSONObj());
+                                        << "wall" << Date_t() << "o" << BSON("_id" << 1 << "a" << 1)
+                                        << "o2" << BSONObj());
     ASSERT_THROWS(updateFixUpInfoFromLocalOplogEntry(
                       nullptr /* opCtx */, OplogInterfaceMock(), fui, invalidOplogEntry, false),
                   RSFatalException);
@@ -1939,7 +1947,7 @@ DEATH_TEST_F(RSRollbackTest, LocalEntryWithTxnNumberWithoutSessionIdIsFatal, "in
                                      << "i"
                                      << "ui" << UUID::gen() << "ns"
                                      << "test.t"
-                                     << "o" << BSON("_id" << 1 << "a" << 1));
+                                     << "wall" << Date_t() << "o" << BSON("_id" << 1 << "a" << 1));
     FixUpInfo fui;
     ASSERT_OK(updateFixUpInfoFromLocalOplogEntry(
         nullptr /* opCtx */, OplogInterfaceMock(), fui, validOplogEntry, false));
@@ -1958,12 +1966,13 @@ TEST_F(RSRollbackTest, LocalEntryWithTxnNumberWithoutTxnTableUUIDIsFatal) {
     // If txnNumber is present, but the transaction collection has no UUID, rollback fails.
     UUID uuid = UUID::gen();
     auto lsid = makeLogicalSessionIdForTest();
-    auto entryWithTxnNumber = BSON("ts" << Timestamp(Seconds(1), 0) << "t" << 1LL << "op"
-                                        << "i"
-                                        << "ui" << uuid << "ns"
-                                        << "test.t"
-                                        << "o" << BSON("_id" << 1 << "a" << 1) << "txnNumber" << 1LL
-                                        << "stmtId" << 1 << "lsid" << lsid.toBSON());
+    auto entryWithTxnNumber =
+        BSON("ts" << Timestamp(Seconds(1), 0) << "t" << 1LL << "op"
+                  << "i"
+                  << "ui" << uuid << "ns"
+                  << "test.t"
+                  << "wall" << Date_t() << "o" << BSON("_id" << 1 << "a" << 1) << "txnNumber" << 1LL
+                  << "stmtId" << 1 << "lsid" << lsid.toBSON());
 
     FixUpInfo fui;
     ASSERT_THROWS(updateFixUpInfoFromLocalOplogEntry(
@@ -1975,11 +1984,12 @@ TEST_F(RSRollbackTest, LocalEntryWithTxnNumberAddsTransactionTableDocToBeRefetch
     FixUpInfo fui;
 
     // With no txnNumber present, no extra documents need to be refetched.
-    auto entryWithoutTxnNumber = BSON("ts" << Timestamp(Seconds(1), 0) << "t" << 1LL << "op"
-                                           << "i"
-                                           << "ui" << UUID::gen() << "ns"
-                                           << "test.t2"
-                                           << "o" << BSON("_id" << 2 << "a" << 2));
+    auto entryWithoutTxnNumber =
+        BSON("ts" << Timestamp(Seconds(1), 0) << "t" << 1LL << "op"
+                  << "i"
+                  << "ui" << UUID::gen() << "ns"
+                  << "test.t2"
+                  << "wall" << Date_t() << "o" << BSON("_id" << 2 << "a" << 2));
 
     ASSERT_OK(updateFixUpInfoFromLocalOplogEntry(
         nullptr /* opCtx */, OplogInterfaceMock(), fui, entryWithoutTxnNumber, false));
@@ -1990,12 +2000,13 @@ TEST_F(RSRollbackTest, LocalEntryWithTxnNumberAddsTransactionTableDocToBeRefetch
     // refetched.
     UUID uuid = UUID::gen();
     auto lsid = makeLogicalSessionIdForTest();
-    auto entryWithTxnNumber = BSON("ts" << Timestamp(Seconds(1), 0) << "t" << 1LL << "op"
-                                        << "i"
-                                        << "ui" << uuid << "ns"
-                                        << "test.t"
-                                        << "o" << BSON("_id" << 1 << "a" << 1) << "txnNumber" << 1LL
-                                        << "stmtId" << 1 << "lsid" << lsid.toBSON());
+    auto entryWithTxnNumber =
+        BSON("ts" << Timestamp(Seconds(1), 0) << "t" << 1LL << "op"
+                  << "i"
+                  << "ui" << uuid << "ns"
+                  << "test.t"
+                  << "wall" << Date_t() << "o" << BSON("_id" << 1 << "a" << 1) << "txnNumber" << 1LL
+                  << "stmtId" << 1 << "lsid" << lsid.toBSON());
     UUID transactionTableUUID = UUID::gen();
     fui.transactionTableUUID = transactionTableUUID;
 
@@ -2022,7 +2033,7 @@ TEST_F(RSRollbackTest, LocalEntryWithPartialTxnAddsTransactionTableDocToBeRefetc
                   << "c"
                   << "ns"
                   << "admin.$cmd"
-                  << "o"
+                  << "wall" << Date_t() << "o"
                   << BSON("applyOps" << BSON_ARRAY(BSON("op"
                                                         << "i"
                                                         << "ui" << uuid << "ns"
@@ -2048,13 +2059,14 @@ TEST_F(RSRollbackTest, LocalAbortTxnRefetchesTransactionTableEntry) {
     FixUpInfo fui;
 
     auto lsid = makeLogicalSessionIdForTest();
-    auto abortTxnEntry = BSON("ts" << Timestamp(Seconds(1), 1) << "t" << 1LL << "op"
-                                   << "c"
-                                   << "ns"
-                                   << "admin.$cmd"
-                                   << "o" << BSON("abortTransaction" << 1) << "txnNumber" << 1LL
-                                   << "stmtId" << 1 << "lsid" << lsid.toBSON() << "prevOpTime"
-                                   << BSON("ts" << Timestamp(Seconds(1), 0) << "t" << 1LL));
+    auto abortTxnEntry =
+        BSON("ts" << Timestamp(Seconds(1), 1) << "t" << 1LL << "op"
+                  << "c"
+                  << "ns"
+                  << "admin.$cmd"
+                  << "wall" << Date_t() << "o" << BSON("abortTransaction" << 1) << "txnNumber"
+                  << 1LL << "stmtId" << 1 << "lsid" << lsid.toBSON() << "prevOpTime"
+                  << BSON("ts" << Timestamp(Seconds(1), 0) << "t" << 1LL));
 
     UUID transactionTableUUID = UUID::gen();
     fui.transactionTableUUID = transactionTableUUID;
@@ -2077,20 +2089,21 @@ TEST_F(RSRollbackTest, LocalEntryWithAbortedPartialTxnRefetchesOnlyTransactionTa
     // that may not have been committed, and even if it is known that the transaction aborted.
     UUID uuid = UUID::gen();
     auto lsid = makeLogicalSessionIdForTest();
-    auto abortTxnEntry = BSON("ts" << Timestamp(Seconds(1), 2) << "t" << 1LL << "op"
-                                   << "c"
-                                   << "ns"
-                                   << "admin.$cmd"
-                                   << "o" << BSON("abortTransaction" << 1) << "txnNumber" << 1LL
-                                   << "stmtId" << 1 << "lsid" << lsid.toBSON() << "prevOpTime"
-                                   << BSON("ts" << Timestamp(Seconds(1), 1) << "t" << 1LL));
+    auto abortTxnEntry =
+        BSON("ts" << Timestamp(Seconds(1), 2) << "t" << 1LL << "op"
+                  << "c"
+                  << "ns"
+                  << "admin.$cmd"
+                  << "wall" << Date_t() << "o" << BSON("abortTransaction" << 1) << "txnNumber"
+                  << 1LL << "stmtId" << 1 << "lsid" << lsid.toBSON() << "prevOpTime"
+                  << BSON("ts" << Timestamp(Seconds(1), 1) << "t" << 1LL));
 
     auto entryWithTxnNumber =
         BSON("ts" << Timestamp(Seconds(1), 1) << "t" << 1LL << "op"
                   << "c"
                   << "ns"
                   << "admin.$cmd"
-                  << "o"
+                  << "wall" << Date_t() << "o"
                   << BSON("applyOps" << BSON_ARRAY(BSON("op"
                                                         << "i"
                                                         << "ui" << uuid << "ns"
@@ -2121,7 +2134,7 @@ TEST_F(RSRollbackTest, LocalEntryWithCommittedTxnRefetchesDocsAndTransactionTabl
                   << "c"
                   << "ns"
                   << "admin.$cmd"
-                  << "o"
+                  << "wall" << Date_t() << "o"
                   << BSON("applyOps" << BSON_ARRAY(BSON("op"
                                                         << "i"
                                                         << "ui" << uuid << "ns"
@@ -2137,7 +2150,7 @@ TEST_F(RSRollbackTest, LocalEntryWithCommittedTxnRefetchesDocsAndTransactionTabl
                   << "c"
                   << "ns"
                   << "admin.$cmd"
-                  << "o"
+                  << "wall" << Date_t() << "o"
                   << BSON("applyOps" << BSON_ARRAY(BSON("op"
                                                         << "i"
                                                         << "ui" << uuid << "ns"
@@ -2194,7 +2207,7 @@ TEST_F(RSRollbackTest, RollbackFetchesTransactionOperationBeforeCommonPoint) {
                   << "c"
                   << "ns"
                   << "admin.$cmd"
-                  << "o"
+                  << "wall" << Date_t() << "o"
                   << BSON("applyOps" << BSON_ARRAY(BSON("op"
                                                         << "i"
                                                         << "ui" << uuid << "ns"
@@ -2210,7 +2223,7 @@ TEST_F(RSRollbackTest, RollbackFetchesTransactionOperationBeforeCommonPoint) {
                   << "c"
                   << "ns"
                   << "admin.$cmd"
-                  << "o"
+                  << "wall" << Date_t() << "o"
                   << BSON("applyOps" << BSON_ARRAY(BSON("op"
                                                         << "i"
                                                         << "ui" << uuid << "ns"
@@ -2226,7 +2239,7 @@ TEST_F(RSRollbackTest, RollbackFetchesTransactionOperationBeforeCommonPoint) {
                   << "c"
                   << "ns"
                   << "admin.$cmd"
-                  << "o"
+                  << "wall" << Date_t() << "o"
                   << BSON("applyOps" << BSON_ARRAY(BSON("op"
                                                         << "i"
                                                         << "ui" << uuid << "ns"
@@ -2308,7 +2321,7 @@ TEST_F(RSRollbackTest, RollbackIncompleteTransactionReturnsUnrecoverableRollback
                   << "c"
                   << "ns"
                   << "admin.$cmd"
-                  << "o"
+                  << "wall" << Date_t() << "o"
                   << BSON("applyOps" << BSON_ARRAY(BSON("op"
                                                         << "i"
                                                         << "ui" << uuid << "ns"
@@ -2324,7 +2337,7 @@ TEST_F(RSRollbackTest, RollbackIncompleteTransactionReturnsUnrecoverableRollback
                   << "c"
                   << "ns"
                   << "admin.$cmd"
-                  << "o"
+                  << "wall" << Date_t() << "o"
                   << BSON("applyOps" << BSON_ARRAY(BSON("op"
                                                         << "i"
                                                         << "ui" << uuid << "ns"
@@ -2379,8 +2392,8 @@ TEST_F(RSRollbackTest, RollbackFailsIfTransactionDocumentRefetchReturnsDifferent
                   << "i"
                   << "ui" << UUID::gen() << "ns"
                   << "test.t"
-                  << "o" << BSON("_id" << 1 << "a" << 1) << "txnNumber" << 1LL << "stmtId" << 1
-                  << "lsid" << makeLogicalSessionIdForTest().toBSON());
+                  << "wall" << Date_t() << "o" << BSON("_id" << 1 << "a" << 1) << "txnNumber" << 1LL
+                  << "stmtId" << 1 << "lsid" << makeLogicalSessionIdForTest().toBSON());
 
     UUID transactionTableUUID = UUID::gen();
     fui.transactionTableUUID = transactionTableUUID;
diff --git a/src/mongo/db/repl/session_update_tracker.cpp b/src/mongo/db/repl/session_update_tracker.cpp
index a251414e014..c539e608670 100644
--- a/src/mongo/db/repl/session_update_tracker.cpp
+++ b/src/mongo/db/repl/session_update_tracker.cpp
@@ -86,14 +86,13 @@ boost::optional<repl::OplogEntry> createMatchingTransactionTableUpdate(
     }
 
     invariant(sessionInfo.getSessionId());
-    invariant(entry.getWallClockTime());
 
     const auto updateBSON = [&] {
         SessionTxnRecord newTxnRecord;
         newTxnRecord.setSessionId(*sessionInfo.getSessionId());
         newTxnRecord.setTxnNum(*sessionInfo.getTxnNumber());
         newTxnRecord.setLastWriteOpTime(entry.getOpTime());
-        newTxnRecord.setLastWriteDate(*entry.getWallClockTime());
+        newTxnRecord.setLastWriteDate(entry.getWallClockTime());
 
         return newTxnRecord.toBSON();
     }();
@@ -102,7 +101,7 @@ boost::optional<repl::OplogEntry> createMatchingTransactionTableUpdate(
         entry.getOpTime(),
         updateBSON,
         BSON(SessionTxnRecord::kSessionIdFieldName << sessionInfo.getSessionId()->toBSON()),
-        *entry.getWallClockTime());
+        entry.getWallClockTime());
 }
 
 /**
@@ -263,14 +262,13 @@ boost::optional<OplogEntry> SessionUpdateTracker::_createTransactionTableUpdateF
         return boost::none;
     }
     invariant(sessionInfo.getSessionId());
-    invariant(entry.getWallClockTime());
 
     const auto updateBSON = [&] {
         SessionTxnRecord newTxnRecord;
         newTxnRecord.setSessionId(*sessionInfo.getSessionId());
         newTxnRecord.setTxnNum(*sessionInfo.getTxnNumber());
         newTxnRecord.setLastWriteOpTime(entry.getOpTime());
-        newTxnRecord.setLastWriteDate(*entry.getWallClockTime());
+        newTxnRecord.setLastWriteDate(entry.getWallClockTime());
 
         if (entry.isPartialTransaction()) {
             invariant(entry.getPrevWriteOpTimeInTransaction()->isNull());
@@ -310,7 +308,7 @@ boost::optional<OplogEntry> SessionUpdateTracker::_createTransactionTableUpdateF
         entry.getOpTime(),
         updateBSON,
         BSON(SessionTxnRecord::kSessionIdFieldName << sessionInfo.getSessionId()->toBSON()),
-        *entry.getWallClockTime());
+        entry.getWallClockTime());
 }
 
 }  // namespace repl
diff --git a/src/mongo/db/repl/sync_source_resolver_test.cpp b/src/mongo/db/repl/sync_source_resolver_test.cpp
index 4337f834c25..a10280c8491 100644
--- a/src/mongo/db/repl/sync_source_resolver_test.cpp
+++ b/src/mongo/db/repl/sync_source_resolver_test.cpp
@@ -309,7 +309,7 @@ BSONObj _makeOplogEntry(Timestamp ts, long long term) {
                       boost::none,                      // o2
                       {},                               // sessionInfo
                       boost::none,                      // upsert
-                      boost::none,                      // wall clock time
+                      Date_t(),                         // wall clock time
                       boost::none,                      // statement id
                       boost::none,  // optime of previous write within same transaction
                       boost::none,  // pre-image optime
diff --git a/src/mongo/db/repl/sync_tail.cpp b/src/mongo/db/repl/sync_tail.cpp
index ebbf4745f9b..a80c26d0af3 100644
--- a/src/mongo/db/repl/sync_tail.cpp
+++ b/src/mongo/db/repl/sync_tail.cpp
@@ -761,9 +761,8 @@ void SyncTail::_oplogApplication(ReplicationCoordinator* replCoord,
         auto consistency = (lastOpTimeInBatch >= minValid)
             ? ReplicationCoordinator::DataConsistency::Consistent
             : ReplicationCoordinator::DataConsistency::Inconsistent;
-        // Wall clock time is non-optional post 3.6.
-        invariant(lastWallTimeInBatch);
-        finalizer->record({lastOpTimeInBatch, lastWallTimeInBatch.get()}, consistency);
+
+        finalizer->record({lastOpTimeInBatch, lastWallTimeInBatch}, consistency);
     }
 }
 
diff --git a/src/mongo/db/repl/sync_tail_test.cpp b/src/mongo/db/repl/sync_tail_test.cpp
index ea9005f4040..bd445689df9 100644
--- a/src/mongo/db/repl/sync_tail_test.cpp
+++ b/src/mongo/db/repl/sync_tail_test.cpp
@@ -92,7 +92,7 @@ OplogEntry makeOplogEntry(OpTypeEnum opType, NamespaceString nss, OptionalCollec
                       boost::none,                 // o2
                       {},                          // sessionInfo
                       boost::none,                 // upsert
-                      boost::none,                 // wall clock time
+                      Date_t(),                    // wall clock time
                       boost::none,                 // statement id
                       boost::none,   // optime of previous write within same transaction
                       boost::none,   // pre-image optime
@@ -278,10 +278,11 @@ TEST_F(SyncTailTest, SyncApplyDeleteDocumentCollectionLockedByUUID) {
 
 TEST_F(SyncTailTest, SyncApplyCommand) {
     NamespaceString nss("test.t");
-    auto op = BSON("op"
-                   << "c"
-                   << "ns" << nss.getCommandNS().ns() << "o" << BSON("create" << nss.coll()) << "ts"
-                   << Timestamp(1, 1) << "ui" << UUID::gen());
+    auto op =
+        BSON("op"
+             << "c"
+             << "ns" << nss.getCommandNS().ns() << "wall" << Date_t() << "o"
+             << BSON("create" << nss.coll()) << "ts" << Timestamp(1, 1) << "ui" << UUID::gen());
     bool applyCmdCalled = false;
     _opObserver->onCreateCollectionFn = [&](OperationContext* opCtx,
                                             Collection*,
@@ -508,7 +509,7 @@ TEST_F(MultiOplogEntrySyncTailTest, MultiApplyUnpreparedTransactionSeparate) {
     checkTxnTable(_lsid,
                   _txnNum,
                   _insertOp1->getOpTime(),
-                  *_insertOp1->getWallClockTime(),
+                  _insertOp1->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kInProgress);
 
@@ -525,7 +526,7 @@ TEST_F(MultiOplogEntrySyncTailTest, MultiApplyUnpreparedTransactionSeparate) {
     checkTxnTable(_lsid,
                   _txnNum,
                   _insertOp1->getOpTime(),
-                  *_insertOp1->getWallClockTime(),
+                  _insertOp1->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kInProgress);
 
@@ -539,7 +540,7 @@ TEST_F(MultiOplogEntrySyncTailTest, MultiApplyUnpreparedTransactionSeparate) {
     checkTxnTable(_lsid,
                   _txnNum,
                   _commitOp->getOpTime(),
-                  *_commitOp->getWallClockTime(),
+                  _commitOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 }
@@ -563,7 +564,7 @@ TEST_F(MultiOplogEntrySyncTailTest, MultiApplyUnpreparedTransactionAllAtOnce) {
     checkTxnTable(_lsid,
                   _txnNum,
                   _commitOp->getOpTime(),
-                  *_commitOp->getWallClockTime(),
+                  _commitOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 }
@@ -617,7 +618,7 @@ TEST_F(MultiOplogEntrySyncTailTest, MultiApplyUnpreparedTransactionTwoBatches) {
     checkTxnTable(_lsid,
                   _txnNum,
                   insertOps[0].getOpTime(),
-                  *insertOps[0].getWallClockTime(),
+                  insertOps[0].getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kInProgress);
 
@@ -631,7 +632,7 @@ TEST_F(MultiOplogEntrySyncTailTest, MultiApplyUnpreparedTransactionTwoBatches) {
     checkTxnTable(_lsid,
                   _txnNum,
                   commitOp.getOpTime(),
-                  *commitOp.getWallClockTime(),
+                  commitOp.getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 
@@ -738,7 +739,7 @@ TEST_F(MultiOplogEntrySyncTailTest, MultiApplyTwoTransactionsOneBatch) {
     checkTxnTable(_lsid,
                   txnNum2,
                   commitOp2.getOpTime(),
-                  *commitOp2.getWallClockTime(),
+                  commitOp2.getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 
@@ -843,7 +844,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyPreparedTransactionStea
     checkTxnTable(_lsid,
                   _txnNum,
                   _insertOp1->getOpTime(),
-                  *_insertOp1->getWallClockTime(),
+                  _insertOp1->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kInProgress);
 
@@ -858,7 +859,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyPreparedTransactionStea
     checkTxnTable(_lsid,
                   _txnNum,
                   _prepareWithPrevOp->getOpTime(),
-                  *_prepareWithPrevOp->getWallClockTime(),
+                  _prepareWithPrevOp->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kPrepared);
 
@@ -871,7 +872,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyPreparedTransactionStea
     checkTxnTable(_lsid,
                   _txnNum,
                   _commitPrepareWithPrevOp->getOpTime(),
-                  *_commitPrepareWithPrevOp->getWallClockTime(),
+                  _commitPrepareWithPrevOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 }
@@ -892,7 +893,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyAbortPreparedTransactio
     checkTxnTable(_lsid,
                   _txnNum,
                   _insertOp1->getOpTime(),
-                  *_insertOp1->getWallClockTime(),
+                  _insertOp1->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kInProgress);
 
@@ -903,7 +904,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyAbortPreparedTransactio
     checkTxnTable(_lsid,
                   _txnNum,
                   _prepareWithPrevOp->getOpTime(),
-                  *_prepareWithPrevOp->getWallClockTime(),
+                  _prepareWithPrevOp->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kPrepared);
 
@@ -916,7 +917,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyAbortPreparedTransactio
     checkTxnTable(_lsid,
                   _txnNum,
                   _abortPrepareWithPrevOp->getOpTime(),
-                  *_abortPrepareWithPrevOp->getWallClockTime(),
+                  _abortPrepareWithPrevOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kAborted);
 }
@@ -942,7 +943,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyPreparedTransactionInit
     checkTxnTable(_lsid,
                   _txnNum,
                   _insertOp1->getOpTime(),
-                  *_insertOp1->getWallClockTime(),
+                  _insertOp1->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kInProgress);
 
@@ -956,7 +957,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyPreparedTransactionInit
     checkTxnTable(_lsid,
                   _txnNum,
                   _prepareWithPrevOp->getOpTime(),
-                  *_prepareWithPrevOp->getWallClockTime(),
+                  _prepareWithPrevOp->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kPrepared);
 
@@ -969,7 +970,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyPreparedTransactionInit
     checkTxnTable(_lsid,
                   _txnNum,
                   _commitPrepareWithPrevOp->getOpTime(),
-                  *_commitPrepareWithPrevOp->getWallClockTime(),
+                  _commitPrepareWithPrevOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 }
@@ -1004,7 +1005,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyPreparedTransactionReco
     checkTxnTable(_lsid,
                   _txnNum,
                   _insertOp1->getOpTime(),
-                  *_insertOp1->getWallClockTime(),
+                  _insertOp1->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kInProgress);
 
@@ -1017,7 +1018,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyPreparedTransactionReco
     checkTxnTable(_lsid,
                   _txnNum,
                   _prepareWithPrevOp->getOpTime(),
-                  *_prepareWithPrevOp->getWallClockTime(),
+                  _prepareWithPrevOp->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kPrepared);
 
@@ -1030,7 +1031,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyPreparedTransactionReco
     checkTxnTable(_lsid,
                   _txnNum,
                   _commitPrepareWithPrevOp->getOpTime(),
-                  *_commitPrepareWithPrevOp->getWallClockTime(),
+                  _commitPrepareWithPrevOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 }
@@ -1054,7 +1055,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplySingleApplyOpsPreparedT
     checkTxnTable(_lsid,
                   _txnNum,
                   _singlePrepareApplyOp->getOpTime(),
-                  *_singlePrepareApplyOp->getWallClockTime(),
+                  _singlePrepareApplyOp->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kPrepared);
 
@@ -1067,7 +1068,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplySingleApplyOpsPreparedT
     checkTxnTable(_lsid,
                   _txnNum,
                   _commitSinglePrepareApplyOp->getOpTime(),
-                  *_commitSinglePrepareApplyOp->getWallClockTime(),
+                  _commitSinglePrepareApplyOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 }
@@ -1099,7 +1100,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyEmptyApplyOpsPreparedTr
     checkTxnTable(_lsid,
                   _txnNum,
                   emptyPrepareApplyOp.getOpTime(),
-                  *emptyPrepareApplyOp.getWallClockTime(),
+                  emptyPrepareApplyOp.getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kPrepared);
 
@@ -1112,7 +1113,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyEmptyApplyOpsPreparedTr
     checkTxnTable(_lsid,
                   _txnNum,
                   _commitSinglePrepareApplyOp->getOpTime(),
-                  *_commitSinglePrepareApplyOp->getWallClockTime(),
+                  _commitSinglePrepareApplyOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 }
@@ -1132,7 +1133,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyAbortSingleApplyOpsPrep
     checkTxnTable(_lsid,
                   _txnNum,
                   _singlePrepareApplyOp->getOpTime(),
-                  *_singlePrepareApplyOp->getWallClockTime(),
+                  _singlePrepareApplyOp->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kPrepared);
 
@@ -1145,7 +1146,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest, MultiApplyAbortSingleApplyOpsPrep
     checkTxnTable(_lsid,
                   _txnNum,
                   _abortSinglePrepareApplyOp->getOpTime(),
-                  *_abortSinglePrepareApplyOp->getWallClockTime(),
+                  _abortSinglePrepareApplyOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kAborted);
 }
@@ -1171,7 +1172,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest,
     checkTxnTable(_lsid,
                   _txnNum,
                   _singlePrepareApplyOp->getOpTime(),
-                  *_singlePrepareApplyOp->getWallClockTime(),
+                  _singlePrepareApplyOp->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kPrepared);
 
@@ -1184,7 +1185,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest,
     checkTxnTable(_lsid,
                   _txnNum,
                   _commitSinglePrepareApplyOp->getOpTime(),
-                  *_commitSinglePrepareApplyOp->getWallClockTime(),
+                  _commitSinglePrepareApplyOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 }
@@ -1220,7 +1221,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest,
     checkTxnTable(_lsid,
                   _txnNum,
                   _singlePrepareApplyOp->getOpTime(),
-                  *_singlePrepareApplyOp->getWallClockTime(),
+                  _singlePrepareApplyOp->getWallClockTime(),
                   expectedStartOpTime,
                   DurableTxnStateEnum::kPrepared);
 
@@ -1233,7 +1234,7 @@ TEST_F(MultiOplogEntryPreparedTransactionTest,
     checkTxnTable(_lsid,
                   _txnNum,
                   _commitSinglePrepareApplyOp->getOpTime(),
-                  *_commitSinglePrepareApplyOp->getWallClockTime(),
+                  _commitSinglePrepareApplyOp->getWallClockTime(),
                   boost::none,
                   DurableTxnStateEnum::kCommitted);
 }
@@ -2202,7 +2203,8 @@ TEST_F(SyncTailTest, LogSlowOpApplicationWhenSuccessful) {
 
     // Use a builder for easier escaping. We expect the operation to be logged.
     StringBuilder expected;
-    expected << "applied op: CRUD { ts: Timestamp(1, 1), t: 1, v: 2, op: \"i\", ns: \"test.t\", o: "
+    expected << "applied op: CRUD { ts: Timestamp(1, 1), t: 1, v: 2, op: \"i\", ns: \"test.t\", "
+                "wall: new Date(0), o: "
                 "{ _id: 0 } }, took "
              << applyDuration << "ms";
     ASSERT_EQUALS(1, countLogLinesContaining(expected.str()));
@@ -2554,7 +2556,7 @@ TEST_F(SyncTailTxnTableTest, RetryableWriteThenMultiStatementTxnWriteOnSameSessi
                         *sessionInfo.getSessionId(),
                         *sessionInfo.getTxnNumber(),
                         txnCommitOpTime,
-                        *txnCommitOp.getWallClockTime(),
+                        txnCommitOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
 }
@@ -2619,7 +2621,7 @@ TEST_F(SyncTailTxnTableTest, MultiStatementTxnWriteThenRetryableWriteOnSameSessi
                         *sessionInfo.getSessionId(),
                         *sessionInfo.getTxnNumber(),
                         retryableInsertOpTime,
-                        *retryableInsertOp.getWallClockTime(),
+                        retryableInsertOp.getWallClockTime(),
                         boost::none,
                         boost::none);
 }
@@ -2879,7 +2881,7 @@ TEST_F(IdempotencyTestTxns, CommitUnpreparedTransaction) {
                         lsid,
                         txnNum,
                         commitOp.getOpTime(),
-                        *commitOp.getWallClockTime(),
+                        commitOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -2917,7 +2919,7 @@ TEST_F(IdempotencyTestTxns, CommitUnpreparedTransactionDataPartiallyApplied) {
                         lsid,
                         txnNum,
                         commitOp.getOpTime(),
-                        *commitOp.getWallClockTime(),
+                        commitOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -2943,7 +2945,7 @@ TEST_F(IdempotencyTestTxns, CommitPreparedTransaction) {
                         lsid,
                         txnNum,
                         commitOp.getOpTime(),
-                        *commitOp.getWallClockTime(),
+                        commitOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -2983,7 +2985,7 @@ TEST_F(IdempotencyTestTxns, CommitPreparedTransactionDataPartiallyApplied) {
                         lsid,
                         txnNum,
                         commitOp.getOpTime(),
-                        *commitOp.getWallClockTime(),
+                        commitOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -3008,7 +3010,7 @@ TEST_F(IdempotencyTestTxns, AbortPreparedTransaction) {
                         lsid,
                         txnNum,
                         abortOp.getOpTime(),
-                        *abortOp.getWallClockTime(),
+                        abortOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kAborted);
     ASSERT_FALSE(docExists(_opCtx.get(), nss, doc));
@@ -3032,7 +3034,7 @@ TEST_F(IdempotencyTestTxns, SinglePartialTxnOp) {
                         lsid,
                         txnNum,
                         partialOp.getOpTime(),
-                        *partialOp.getWallClockTime(),
+                        partialOp.getWallClockTime(),
                         expectedStartOpTime,
                         DurableTxnStateEnum::kInProgress);
 
@@ -3062,7 +3064,7 @@ TEST_F(IdempotencyTestTxns, MultiplePartialTxnOps) {
                         lsid,
                         txnNum,
                         partialOp1.getOpTime(),
-                        *partialOp1.getWallClockTime(),
+                        partialOp1.getWallClockTime(),
                         expectedStartOpTime,
                         DurableTxnStateEnum::kInProgress);
     // Document should not be visible yet.
@@ -3093,7 +3095,7 @@ TEST_F(IdempotencyTestTxns, CommitUnpreparedTransactionWithPartialTxnOps) {
                         lsid,
                         txnNum,
                         commitOp.getOpTime(),
-                        *commitOp.getWallClockTime(),
+                        commitOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -3132,7 +3134,7 @@ TEST_F(IdempotencyTestTxns, CommitTwoUnpreparedTransactionsWithPartialTxnOpsAtOn
                         lsid,
                         txnNum2,
                         commitOp2.getOpTime(),
-                        *commitOp2.getWallClockTime(),
+                        commitOp2.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -3170,7 +3172,7 @@ TEST_F(IdempotencyTestTxns, CommitAndAbortTwoTransactionsWithPartialTxnOpsAtOnce
                         lsid,
                         txnNum2,
                         commitOp2.getOpTime(),
-                        *commitOp2.getWallClockTime(),
+                        commitOp2.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_FALSE(docExists(_opCtx.get(), nss, doc));
@@ -3209,7 +3211,7 @@ TEST_F(IdempotencyTestTxns, CommitUnpreparedTransactionWithPartialTxnOpsAndDataP
                         lsid,
                         txnNum,
                         commitOp.getOpTime(),
-                        *commitOp.getWallClockTime(),
+                        commitOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -3238,7 +3240,7 @@ TEST_F(IdempotencyTestTxns, PrepareTransactionWithPartialTxnOps) {
                         lsid,
                         txnNum,
                         prepareOp.getOpTime(),
-                        *prepareOp.getWallClockTime(),
+                        prepareOp.getWallClockTime(),
                         partialOp.getOpTime(),
                         DurableTxnStateEnum::kPrepared);
     // Document should not be visible yet.
@@ -3261,7 +3263,7 @@ TEST_F(IdempotencyTestTxns, EmptyPrepareTransaction) {
                         lsid,
                         txnNum,
                         prepareOp.getOpTime(),
-                        *prepareOp.getWallClockTime(),
+                        prepareOp.getWallClockTime(),
                         prepareOp.getOpTime(),
                         DurableTxnStateEnum::kPrepared);
 }
@@ -3289,7 +3291,7 @@ TEST_F(IdempotencyTestTxns, CommitPreparedTransactionWithPartialTxnOps) {
                         lsid,
                         txnNum,
                         commitOp.getOpTime(),
-                        *commitOp.getWallClockTime(),
+                        commitOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -3328,7 +3330,7 @@ TEST_F(IdempotencyTestTxns, CommitTwoPreparedTransactionsWithPartialTxnOpsAtOnce
                         lsid,
                         txnNum2,
                         commitOp2.getOpTime(),
-                        *commitOp2.getWallClockTime(),
+                        commitOp2.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -3367,7 +3369,7 @@ TEST_F(IdempotencyTestTxns, CommitPreparedTransactionWithPartialTxnOpsAndDataPar
                         lsid,
                         txnNum,
                         commitOp.getOpTime(),
-                        *commitOp.getWallClockTime(),
+                        commitOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kCommitted);
     ASSERT_TRUE(docExists(_opCtx.get(), nss, doc));
@@ -3397,7 +3399,7 @@ TEST_F(IdempotencyTestTxns, AbortPreparedTransactionWithPartialTxnOps) {
                         lsid,
                         txnNum,
                         abortOp.getOpTime(),
-                        *abortOp.getWallClockTime(),
+                        abortOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kAborted);
     ASSERT_FALSE(docExists(_opCtx.get(), nss, doc));
@@ -3422,7 +3424,7 @@ TEST_F(IdempotencyTestTxns, AbortInProgressTransaction) {
                         lsid,
                         txnNum,
                         abortOp.getOpTime(),
-                        *abortOp.getWallClockTime(),
+                        abortOp.getWallClockTime(),
                         boost::none,
                         DurableTxnStateEnum::kAborted);
     ASSERT_FALSE(docExists(_opCtx.get(), nss, doc));
diff --git a/src/mongo/db/s/session_catalog_migration_destination.cpp b/src/mongo/db/s/session_catalog_migration_destination.cpp
index 18e16428f63..ea24c80f7e3 100644
--- a/src/mongo/db/s/session_catalog_migration_destination.cpp
+++ b/src/mongo/db/s/session_catalog_migration_destination.cpp
@@ -126,10 +126,6 @@ void setPrePostImageTs(const ProcessOplogResult& lastResult, repl::MutableOplogE
 repl::MutableOplogEntry parseOplog(const BSONObj& oplogBSON) {
     auto oplogEntry = uassertStatusOK(repl::MutableOplogEntry::parse(oplogBSON));
 
-    // Session oplog entries must always contain wall clock time, because we will not be
-    // transferring anything from a previous version of the server
-    invariant(oplogEntry.getWallClockTime());
-
     const auto& sessionInfo = oplogEntry.getOperationSessionInfo();
 
     uassert(ErrorCodes::UnsupportedFormat,
@@ -292,7 +288,7 @@ ProcessOplogResult processSessionOplog(const BSONObj& oplogBSON,
                 sessionTxnRecord.setSessionId(result.sessionId);
                 sessionTxnRecord.setTxnNum(result.txnNum);
                 sessionTxnRecord.setLastWriteOpTime(oplogOpTime);
-                sessionTxnRecord.setLastWriteDate(*oplogEntry.getWallClockTime());
+                sessionTxnRecord.setLastWriteDate(oplogEntry.getWallClockTime());
                 // We do not migrate transaction oplog entries so don't set the txn state.
                 txnParticipant.onMigrateCompletedOnPrimary(opCtx, {stmtId}, sessionTxnRecord);
             }
diff --git a/src/mongo/db/s/session_catalog_migration_destination_test.cpp b/src/mongo/db/s/session_catalog_migration_destination_test.cpp
index 9305b610070..bf0f3dbf976 100644
--- a/src/mongo/db/s/session_catalog_migration_destination_test.cpp
+++ b/src/mongo/db/s/session_catalog_migration_destination_test.cpp
@@ -87,7 +87,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
                                 BSONObj object,
                                 boost::optional<BSONObj> object2,
                                 OperationSessionInfo sessionInfo,
-                                boost::optional<Date_t> wallClockTime,
+                                Date_t wallClockTime,
                                 boost::optional<StmtId> stmtId,
                                 boost::optional<repl::OpTime> preImageOpTime = boost::none,
                                 boost::optional<repl::OpTime> postImageOpTime = boost::none) {
@@ -596,7 +596,7 @@ TEST_F(SessionCatalogMigrationDestinationTest, ShouldNotNestAlreadyNestedOplog)
                                           BSON("x" << 100),              // o
                                           boost::none,                   // o2
                                           sessionInfo,                   // session info
-                                          boost::none,                   // wall clock time
+                                          Date_t(),                      // wall clock time
                                           23);                           // statement id
 
     auto origInnerOplog2 = makeOplogEntry(OpTime(Timestamp(80, 2), 1),  // optime
@@ -604,7 +604,7 @@ TEST_F(SessionCatalogMigrationDestinationTest, ShouldNotNestAlreadyNestedOplog)
                                           BSON("x" << 80),              // o
                                           boost::none,                  // o2
                                           sessionInfo,                  // session info
-                                          boost::none,                  // wall clock time
+                                          Date_t(),                     // wall clock time
                                           45);                          // statement id
 
     auto oplog1 = makeOplogEntry(OpTime(Timestamp(1100, 2), 1),  // optime
diff --git a/src/mongo/db/s/session_catalog_migration_source_test.cpp b/src/mongo/db/s/session_catalog_migration_source_test.cpp
index 3d87181a6bf..5773559a5ea 100644
--- a/src/mongo/db/s/session_catalog_migration_source_test.cpp
+++ b/src/mongo/db/s/session_catalog_migration_source_test.cpp
@@ -59,7 +59,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
                                 NamespaceString nss,
                                 BSONObj object,
                                 boost::optional<BSONObj> object2,
-                                boost::optional<Date_t> wallClockTime,
+                                Date_t wallClockTime,
                                 StmtId stmtId,
                                 repl::OpTime prevWriteOpTimeInTransaction,
                                 boost::optional<repl::OpTime> preImageOpTime,
@@ -87,7 +87,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
                                 repl::OpTypeEnum opType,
                                 BSONObj object,
                                 boost::optional<BSONObj> object2,
-                                boost::optional<Date_t> wallClockTime,
+                                Date_t wallClockTime,
                                 StmtId stmtId,
                                 repl::OpTime prevWriteOpTimeInTransaction,
                                 boost::optional<repl::OpTime> preImageOpTime = boost::none,
@@ -135,7 +135,7 @@ TEST_F(SessionCatalogMigrationSourceTest, OneSessionWithTwoWrites) {
     sessionRecord.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord.setTxnNum(1);
     sessionRecord.setLastWriteOpTime(entry2.getOpTime());
-    sessionRecord.setLastWriteDate(*entry2.getWallClockTime());
+    sessionRecord.setLastWriteDate(entry2.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(), sessionRecord.toBSON());
@@ -187,7 +187,7 @@ TEST_F(SessionCatalogMigrationSourceTest, TwoSessionWithTwoWrites) {
     sessionRecord1.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord1.setTxnNum(1);
     sessionRecord1.setLastWriteOpTime(entry1b.getOpTime());
-    sessionRecord1.setLastWriteDate(*entry1b.getWallClockTime());
+    sessionRecord1.setLastWriteDate(entry1b.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(),
@@ -215,7 +215,7 @@ TEST_F(SessionCatalogMigrationSourceTest, TwoSessionWithTwoWrites) {
     sessionRecord2.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord2.setTxnNum(1);
     sessionRecord2.setLastWriteOpTime(entry2b.getOpTime());
-    sessionRecord2.setLastWriteDate(*entry2b.getWallClockTime());
+    sessionRecord2.setLastWriteDate(entry2b.getWallClockTime());
 
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(),
                   sessionRecord2.toBSON());
@@ -316,7 +316,7 @@ TEST_F(SessionCatalogMigrationSourceTest, OneSessionWithFindAndModifyPreImageAnd
     sessionRecord.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord.setTxnNum(1);
     sessionRecord.setLastWriteOpTime(entry4.getOpTime());
-    sessionRecord.setLastWriteDate(*entry4.getWallClockTime());
+    sessionRecord.setLastWriteDate(entry4.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(), sessionRecord.toBSON());
@@ -353,7 +353,7 @@ TEST_F(SessionCatalogMigrationSourceTest, OplogWithOtherNsShouldBeIgnored) {
     sessionRecord1.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord1.setTxnNum(1);
     sessionRecord1.setLastWriteOpTime(entry1.getOpTime());
-    sessionRecord1.setLastWriteDate(*entry1.getWallClockTime());
+    sessionRecord1.setLastWriteDate(entry1.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(),
@@ -377,7 +377,7 @@ TEST_F(SessionCatalogMigrationSourceTest, OplogWithOtherNsShouldBeIgnored) {
     sessionRecord2.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord2.setTxnNum(1);
     sessionRecord2.setLastWriteOpTime(entry2.getOpTime());
-    sessionRecord2.setLastWriteDate(*entry2.getWallClockTime());
+    sessionRecord2.setLastWriteDate(entry2.getWallClockTime());
 
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(),
                   sessionRecord2.toBSON());
@@ -411,7 +411,7 @@ TEST_F(SessionCatalogMigrationSourceTest, SessionDumpWithMultipleNewWrites) {
     sessionRecord1.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord1.setTxnNum(1);
     sessionRecord1.setLastWriteOpTime(entry1.getOpTime());
-    sessionRecord1.setLastWriteDate(*entry1.getWallClockTime());
+    sessionRecord1.setLastWriteDate(entry1.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(),
@@ -579,7 +579,7 @@ TEST_F(SessionCatalogMigrationSourceTest, ReturnsDeadEndSentinelForIncompleteHis
     sessionRecord.setSessionId(sessionId);
     sessionRecord.setTxnNum(31);
     sessionRecord.setLastWriteOpTime(entry.getOpTime());
-    sessionRecord.setLastWriteDate(*entry.getWallClockTime());
+    sessionRecord.setLastWriteDate(entry.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(), sessionRecord.toBSON());
@@ -606,8 +606,7 @@ TEST_F(SessionCatalogMigrationSourceTest, ReturnsDeadEndSentinelForIncompleteHis
         ASSERT_BSONOBJ_EQ(TransactionParticipant::kDeadEndSentinel, *oplog.getObject2());
         ASSERT_TRUE(oplog.getStatementId());
         ASSERT_EQ(kIncompleteHistoryStmtId, *oplog.getStatementId());
-        ASSERT_TRUE(oplog.getWallClockTime());
-        ASSERT_NE(Date_t{}, *oplog.getWallClockTime());
+        ASSERT_NE(Date_t{}, oplog.getWallClockTime());
 
         auto sessionInfo = oplog.getOperationSessionInfo();
         ASSERT_TRUE(sessionInfo.getSessionId());
@@ -637,7 +636,7 @@ TEST_F(SessionCatalogMigrationSourceTest, ShouldAssertWhenRollbackDetected) {
     sessionRecord.setSessionId(sessionId);
     sessionRecord.setTxnNum(31);
     sessionRecord.setLastWriteOpTime(entry.getOpTime());
-    sessionRecord.setLastWriteDate(*entry.getWallClockTime());
+    sessionRecord.setLastWriteDate(entry.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(), sessionRecord.toBSON());
@@ -762,7 +761,7 @@ TEST_F(SessionCatalogMigrationSourceTest,
     retryableWriteRecord.setSessionId(makeLogicalSessionIdForTest());
     retryableWriteRecord.setTxnNum(1);
     retryableWriteRecord.setLastWriteOpTime(insertOplog.getOpTime());
-    retryableWriteRecord.setLastWriteDate(*insertOplog.getWallClockTime());
+    retryableWriteRecord.setLastWriteDate(insertOplog.getWallClockTime());
 
     // Create a config.transaction entry pointing to an imaginary commitTransaction entry.
     SessionTxnRecord txnRecord;
@@ -847,7 +846,7 @@ TEST_F(SessionCatalogMigrationSourceTest, FindAndModifyDeleteNotTouchingChunkIsI
     sessionRecord.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord.setTxnNum(1);
     sessionRecord.setLastWriteOpTime(entry2.getOpTime());
-    sessionRecord.setLastWriteDate(*entry2.getWallClockTime());
+    sessionRecord.setLastWriteDate(entry2.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(), sessionRecord.toBSON());
@@ -882,7 +881,7 @@ TEST_F(SessionCatalogMigrationSourceTest, FindAndModifyUpdatePrePostNotTouchingC
     sessionRecord.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord.setTxnNum(1);
     sessionRecord.setLastWriteOpTime(entry2.getOpTime());
-    sessionRecord.setLastWriteDate(*entry2.getWallClockTime());
+    sessionRecord.setLastWriteDate(entry2.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(), sessionRecord.toBSON());
@@ -919,7 +918,7 @@ TEST_F(SessionCatalogMigrationSourceTest,
     sessionRecord.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord.setTxnNum(1);
     sessionRecord.setLastWriteOpTime(entry2.getOpTime());
-    sessionRecord.setLastWriteDate(*entry2.getWallClockTime());
+    sessionRecord.setLastWriteDate(entry2.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(), sessionRecord.toBSON());
@@ -969,7 +968,7 @@ TEST_F(SessionCatalogMigrationSourceTest,
     sessionRecord.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord.setTxnNum(1);
     sessionRecord.setLastWriteOpTime(entry2.getOpTime());
-    sessionRecord.setLastWriteDate(*entry2.getWallClockTime());
+    sessionRecord.setLastWriteDate(entry2.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(), sessionRecord.toBSON());
@@ -1005,7 +1004,7 @@ TEST_F(SessionCatalogMigrationSourceTest, FindAndModifyUpdateNotTouchingChunkSho
     sessionRecord.setSessionId(makeLogicalSessionIdForTest());
     sessionRecord.setTxnNum(1);
     sessionRecord.setLastWriteOpTime(entry2.getOpTime());
-    sessionRecord.setLastWriteDate(*entry2.getWallClockTime());
+    sessionRecord.setLastWriteDate(entry2.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(), sessionRecord.toBSON());
@@ -1044,7 +1043,7 @@ TEST_F(SessionCatalogMigrationSourceTest, TwoSessionWithTwoWritesContainingWrite
     sessionRecord1.setSessionId(higherSessionId);
     sessionRecord1.setTxnNum(1);
     sessionRecord1.setLastWriteOpTime(entry1b.getOpTime());
-    sessionRecord1.setLastWriteDate(*entry1b.getWallClockTime());
+    sessionRecord1.setLastWriteDate(entry1b.getWallClockTime());
 
     DBDirectClient client(opCtx());
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(),
@@ -1072,7 +1071,7 @@ TEST_F(SessionCatalogMigrationSourceTest, TwoSessionWithTwoWritesContainingWrite
     sessionRecord2.setSessionId(lowerSessionId);
     sessionRecord2.setTxnNum(1);
     sessionRecord2.setLastWriteOpTime(entry2b.getOpTime());
-    sessionRecord2.setLastWriteDate(*entry2b.getWallClockTime());
+    sessionRecord2.setLastWriteDate(entry2b.getWallClockTime());
 
     client.insert(NamespaceString::kSessionTransactionsTableNamespace.ns(),
                   sessionRecord2.toBSON());
diff --git a/src/mongo/db/transaction_history_iterator_test.cpp b/src/mongo/db/transaction_history_iterator_test.cpp
index 50f8a51192d..e57c1d1e7ca 100644
--- a/src/mongo/db/transaction_history_iterator_test.cpp
+++ b/src/mongo/db/transaction_history_iterator_test.cpp
@@ -72,7 +72,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
         boost::none,                      // o2
         {},                               // sessionInfo
         boost::none,                      // upsert
-        boost::none,                      // wall clock time
+        Date_t(),                         // wall clock time
         boost::none,                      // statement id
         prevWriteOpTimeInTransaction,     // optime of previous write within same transaction
         boost::none,                      // pre-image optime
diff --git a/src/mongo/db/transaction_participant_retryable_writes_test.cpp b/src/mongo/db/transaction_participant_retryable_writes_test.cpp
index 7203a1c1ddf..a9ffbfaf35c 100644
--- a/src/mongo/db/transaction_participant_retryable_writes_test.cpp
+++ b/src/mongo/db/transaction_participant_retryable_writes_test.cpp
@@ -64,7 +64,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
                                 repl::OpTypeEnum opType,
                                 BSONObj object,
                                 OperationSessionInfo sessionInfo,
-                                boost::optional<Date_t> wallClockTime,
+                                Date_t wallClockTime,
                                 boost::optional<StmtId> stmtId,
                                 boost::optional<repl::OpTime> prevWriteOpTimeInTransaction) {
     return repl::OplogEntry(
@@ -554,7 +554,7 @@ TEST_F(TransactionParticipantRetryableWritesTest, IncompleteHistoryDueToOpLogTru
             sessionRecord.setSessionId(sessionId);
             sessionRecord.setTxnNum(txnNum);
             sessionRecord.setLastWriteOpTime(entry2.getOpTime());
-            sessionRecord.setLastWriteDate(*entry2.getWallClockTime());
+            sessionRecord.setLastWriteDate(entry2.getWallClockTime());
             return sessionRecord.toBSON();
         }());
     }
diff --git a/src/mongo/db/transaction_participant_test.cpp b/src/mongo/db/transaction_participant_test.cpp
index 88bec24896e..c80293146ad 100644
--- a/src/mongo/db/transaction_participant_test.cpp
+++ b/src/mongo/db/transaction_participant_test.cpp
@@ -72,7 +72,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
                                 repl::OpTypeEnum opType,
                                 BSONObj object,
                                 OperationSessionInfo sessionInfo,
-                                boost::optional<Date_t> wallClockTime,
+                                Date_t wallClockTime,
                                 boost::optional<StmtId> stmtId,
                                 boost::optional<repl::OpTime> prevWriteOpTimeInTransaction) {
     return repl::OplogEntry(
diff --git a/src/mongo/dbtests/repltests.cpp b/src/mongo/dbtests/repltests.cpp
index 51eb8702c3d..f91068cfabb 100644
--- a/src/mongo/dbtests/repltests.cpp
+++ b/src/mongo/dbtests/repltests.cpp
@@ -80,7 +80,7 @@ repl::OplogEntry makeOplogEntry(repl::OpTime opTime,
                             object2,                    // o2
                             {},                         // sessionInfo
                             boost::none,                // upsert
-                            boost::none,                // wall clock time
+                            Date_t(),                   // wall clock time
                             boost::none,                // statement id
                             boost::none,   // optime of previous write within same transaction
                             boost::none,   // pre-image optime
diff --git a/src/mongo/dbtests/storage_timestamp_tests.cpp b/src/mongo/dbtests/storage_timestamp_tests.cpp
index 23d66829265..2c81636f857 100644
--- a/src/mongo/dbtests/storage_timestamp_tests.cpp
+++ b/src/mongo/dbtests/storage_timestamp_tests.cpp
@@ -712,13 +712,14 @@ public:
                                    << "v" << 2 << "op"
                                    << "i"
                                    << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid()
-                                   << "o" << BSON("_id" << idx))
+                                   << "wall" << Date_t() << "o" << BSON("_id" << idx))
                          << BSON("ts" << firstInsertTime.addTicks(idx).asTimestamp() << "t" << 1LL
                                       << "op"
                                       << "c"
                                       << "ns"
                                       << "test.$cmd"
-                                      << "o" << BSON("applyOps" << BSONArrayBuilder().obj())))),
+                                      << "wall" << Date_t() << "o"
+                                      << BSON("applyOps" << BSONArrayBuilder().obj())))),
                 repl::OplogApplication::Mode::kApplyOpsCmd,
                 &result));
         }
@@ -752,7 +753,8 @@ public:
         BSONObjBuilder oplogCommonBuilder;
         oplogCommonBuilder << "v" << 2 << "op"
                            << "i"
-                           << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid();
+                           << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid() << "wall"
+                           << Date_t();
         auto oplogCommon = oplogCommonBuilder.done();
 
         std::vector<repl::OplogEntry> oplogEntries;
@@ -767,6 +769,8 @@ public:
             oplogEntryBuilders[idx] << "t" << 1LL;
             // Populate the "o" field.
             oplogEntryBuilders[idx] << "o" << o;
+            // Populate the "wall" field
+            oplogEntryBuilders[idx] << "wall" << Date_t();
             // Populate the other common fields.
             oplogEntryBuilders[idx].appendElementsUnique(oplogCommon);
             // Insert ops to be applied.
@@ -824,7 +828,7 @@ public:
                                      << "v" << 2 << "op"
                                      << "d"
                                      << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid()
-                                     << "o" << BSON("_id" << num))})
+                                     << "wall" << Date_t() << "o" << BSON("_id" << num))})
                           .getStatus());
         }
 
@@ -883,7 +887,8 @@ public:
                                      << "v" << 2 << "op"
                                      << "u"
                                      << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid()
-                                     << "o2" << BSON("_id" << 0) << "o" << updates[idx].first)})
+                                     << "wall" << Date_t() << "o2" << BSON("_id" << 0) << "o"
+                                     << updates[idx].first)})
                           .getStatus());
         }
 
@@ -921,12 +926,12 @@ public:
             nss.db().toString(),
             {BSON("ts" << insertTime.asTimestamp() << "t" << 1LL << "op"
                        << "i"
-                       << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid() << "o"
-                       << BSON("_id" << 0 << "field" << 0)),
+                       << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid() << "wall"
+                       << Date_t() << "o" << BSON("_id" << 0 << "field" << 0)),
              BSON("ts" << insertTime.addTicks(1).asTimestamp() << "t" << 1LL << "op"
                        << "i"
-                       << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid() << "o"
-                       << BSON("_id" << 0))}));
+                       << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid() << "wall"
+                       << Date_t() << "o" << BSON("_id" << 0))}));
 
         ASSERT_EQ(2, result.getIntField("applied"));
         ASSERT(result["results"].Array()[0].Bool());
@@ -1068,8 +1073,8 @@ public:
             {
                 BSON("ts" << presentTs << "t" << 1LL << "op"
                           << "c"
-                          << "ui" << UUID::gen() << "ns" << nss.getCommandNS().ns() << "o"
-                          << BSON("create" << nss.coll())),
+                          << "ui" << UUID::gen() << "ns" << nss.getCommandNS().ns() << "wall"
+                          << Date_t() << "o" << BSON("create" << nss.coll())),
             });
         ASSERT_OK(swResult);
 
@@ -1106,12 +1111,12 @@ public:
             {
                 BSON("ts" << presentTs << "t" << 1LL << "op"
                           << "c"
-                          << "ui" << UUID::gen() << "ns" << nss1.getCommandNS().ns() << "o"
-                          << BSON("create" << nss1.coll())),
+                          << "ui" << UUID::gen() << "ns" << nss1.getCommandNS().ns() << "wall"
+                          << Date_t() << "o" << BSON("create" << nss1.coll())),
                 BSON("ts" << futureTs << "t" << 1LL << "op"
                           << "c"
-                          << "ui" << UUID::gen() << "ns" << nss2.getCommandNS().ns() << "o"
-                          << BSON("create" << nss2.coll())),
+                          << "ui" << UUID::gen() << "ns" << nss2.getCommandNS().ns() << "wall"
+                          << Date_t() << "o" << BSON("create" << nss2.coll())),
             });
         ASSERT_OK(swResult);
 
@@ -1166,14 +1171,15 @@ public:
                     BSON("ts" << presentTs << "t" << 1LL << "op"
                               << "i"
                               << "ns" << nss1.ns() << "ui" << autoColl.getCollection()->uuid()
-                              << "o" << doc1),
+                              << "wall" << Date_t() << "o" << doc1),
                     BSON("ts" << futureTs << "t" << 1LL << "op"
                               << "c"
-                              << "ui" << uuid2 << "ns" << nss2.getCommandNS().ns() << "o"
-                              << BSON("create" << nss2.coll())),
+                              << "ui" << uuid2 << "ns" << nss2.getCommandNS().ns() << "wall"
+                              << Date_t() << "o" << BSON("create" << nss2.coll())),
                     BSON("ts" << insert2Ts << "t" << 1LL << "op"
                               << "i"
-                              << "ns" << nss2.ns() << "ui" << uuid2 << "o" << doc2),
+                              << "ns" << nss2.ns() << "ui" << uuid2 << "wall" << Date_t() << "o"
+                              << doc2),
                 });
             ASSERT_OK(swResult);
         }
@@ -1224,8 +1230,8 @@ public:
             {
                 BSON("ts" << presentTs << "t" << 1LL << "op"
                           << "c"
-                          << "ui" << UUID::gen() << "ns" << nss.getCommandNS().ns() << "o"
-                          << BSON("create" << nss.coll())),
+                          << "ui" << UUID::gen() << "ns" << nss.getCommandNS().ns() << "wall"
+                          << Date_t() << "o" << BSON("create" << nss.coll())),
             });
         ASSERT_OK(swResult);
 
@@ -1278,18 +1284,18 @@ public:
         BSONObj doc0 = BSON("_id" << 0 << "a" << 3);
         BSONObj doc1 = BSON("_id" << 1 << "a" << BSON_ARRAY(1 << 2));
         BSONObj doc2 = BSON("_id" << 2 << "a" << BSON_ARRAY(1 << 2));
-        auto op0 = repl::OplogEntry(BSON("ts" << insertTime0.asTimestamp() << "t" << 1LL << "v" << 2
-                                              << "op"
-                                              << "i"
-                                              << "ns" << nss.ns() << "ui" << uuid << "o" << doc0));
-        auto op1 = repl::OplogEntry(BSON("ts" << insertTime1.asTimestamp() << "t" << 1LL << "v" << 2
-                                              << "op"
-                                              << "i"
-                                              << "ns" << nss.ns() << "ui" << uuid << "o" << doc1));
-        auto op2 = repl::OplogEntry(BSON("ts" << insertTime2.asTimestamp() << "t" << 1LL << "v" << 2
-                                              << "op"
-                                              << "i"
-                                              << "ns" << nss.ns() << "ui" << uuid << "o" << doc2));
+        auto op0 = repl::OplogEntry(
+            BSON("ts" << insertTime0.asTimestamp() << "t" << 1LL << "v" << 2 << "op"
+                      << "i"
+                      << "ns" << nss.ns() << "ui" << uuid << "wall" << Date_t() << "o" << doc0));
+        auto op1 = repl::OplogEntry(
+            BSON("ts" << insertTime1.asTimestamp() << "t" << 1LL << "v" << 2 << "op"
+                      << "i"
+                      << "ns" << nss.ns() << "ui" << uuid << "wall" << Date_t() << "o" << doc1));
+        auto op2 = repl::OplogEntry(
+            BSON("ts" << insertTime2.asTimestamp() << "t" << 1LL << "v" << 2 << "op"
+                      << "i"
+                      << "ns" << nss.ns() << "ui" << uuid << "wall" << Date_t() << "o" << doc2));
         std::vector<repl::OplogEntry> ops = {op0, op1, op2};
 
         DoNothingOplogApplierObserver observer;
@@ -1349,18 +1355,18 @@ public:
         BSONObj doc0 = BSON("_id" << 0 << "a" << 3);
         BSONObj doc1 = BSON("_id" << 1 << "a" << BSON_ARRAY(1 << 2));
         BSONObj doc2 = BSON("_id" << 2 << "a" << BSON_ARRAY(1 << 2));
-        auto op0 = repl::OplogEntry(BSON("ts" << insertTime0.asTimestamp() << "t" << 1LL << "v" << 2
-                                              << "op"
-                                              << "i"
-                                              << "ns" << nss.ns() << "ui" << uuid << "o" << doc0));
-        auto op1 = repl::OplogEntry(BSON("ts" << insertTime1.asTimestamp() << "t" << 1LL << "v" << 2
-                                              << "op"
-                                              << "i"
-                                              << "ns" << nss.ns() << "ui" << uuid << "o" << doc1));
-        auto op2 = repl::OplogEntry(BSON("ts" << insertTime2.asTimestamp() << "t" << 1LL << "v" << 2
-                                              << "op"
-                                              << "i"
-                                              << "ns" << nss.ns() << "ui" << uuid << "o" << doc2));
+        auto op0 = repl::OplogEntry(
+            BSON("ts" << insertTime0.asTimestamp() << "t" << 1LL << "v" << 2 << "op"
+                      << "i"
+                      << "ns" << nss.ns() << "ui" << uuid << "wall" << Date_t() << "o" << doc0));
+        auto op1 = repl::OplogEntry(
+            BSON("ts" << insertTime1.asTimestamp() << "t" << 1LL << "v" << 2 << "op"
+                      << "i"
+                      << "ns" << nss.ns() << "ui" << uuid << "wall" << Date_t() << "o" << doc1));
+        auto op2 = repl::OplogEntry(
+            BSON("ts" << insertTime2.asTimestamp() << "t" << 1LL << "v" << 2 << "op"
+                      << "i"
+                      << "ns" << nss.ns() << "ui" << uuid << "wall" << Date_t() << "o" << doc2));
         auto indexSpec2 =
             BSON("createIndexes" << nss.coll() << "v" << static_cast<int>(kIndexVersion) << "key"
                                  << BSON("b" << 1) << "name"
@@ -1368,7 +1374,8 @@ public:
         auto createIndexOp = repl::OplogEntry(
             BSON("ts" << indexBuildTime.asTimestamp() << "t" << 1LL << "v" << 2 << "op"
                       << "c"
-                      << "ns" << nss.getCommandNS().ns() << "ui" << uuid << "o" << indexSpec2));
+                      << "ns" << nss.getCommandNS().ns() << "ui" << uuid << "wall" << Date_t()
+                      << "o" << indexSpec2));
 
         // We add in an index creation op to test that we restart tracking multikey path info
         // after bulk index builds.
@@ -2435,10 +2442,10 @@ public:
 
         // Make a simple insert operation.
         BSONObj doc0 = BSON("_id" << 0 << "a" << 0);
-        auto insertOp =
-            repl::OplogEntry(BSON("ts" << futureTs << "t" << 1LL << "v" << 2 << "op"
-                                       << "i"
-                                       << "ns" << ns.ns() << "ui" << uuid << "o" << doc0));
+        auto insertOp = repl::OplogEntry(BSON("ts" << futureTs << "t" << 1LL << "v" << 2 << "op"
+                                                   << "i"
+                                                   << "ns" << ns.ns() << "ui" << uuid << "wall"
+                                                   << Date_t() << "o" << doc0));
 
         // Apply the operation.
         auto storageInterface = repl::StorageInterface::get(_opCtx);
@@ -2528,7 +2535,7 @@ public:
             auto createIndexOp = BSON("ts" << startBuildTs << "t" << 1LL << "v" << 2 << "op"
                                            << "c"
                                            << "ns" << nss.getCommandNS().ns() << "ui" << collUUID
-                                           << "o" << indexSpec);
+                                           << "wall" << Date_t() << "o" << indexSpec);
 
             ASSERT_OK(doAtomicApplyOps(nss.db().toString(), {createIndexOp}));