SERVER-42194 Make Collection always hold a UUID (rather than optional UUID)

41 files changed, 192 insertions, 229 deletions

diff --git a/src/mongo/db/catalog/capped_utils.cpp b/src/mongo/db/catalog/capped_utils.cpp
index 889ca73ddd2..c7ceead85a0 100644
--- a/src/mongo/db/catalog/capped_utils.cpp
+++ b/src/mongo/db/catalog/capped_utils.cpp
@@ -91,8 +91,7 @@ Status emptyCapped(OperationContext* opCtx, const NamespaceString& collectionNam
     }
 
     BackgroundOperation::assertNoBgOpInProgForNs(collectionName.ns());
-    IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(
-        collection->uuid().get());
+    IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(collection->uuid());
 
     WriteUnitOfWork wuow(opCtx);
 
diff --git a/src/mongo/db/catalog/catalog_control.cpp b/src/mongo/db/catalog/catalog_control.cpp
index 95c1381f91e..ab925ab0a97 100644
--- a/src/mongo/db/catalog/catalog_control.cpp
+++ b/src/mongo/db/catalog/catalog_control.cpp
@@ -174,11 +174,9 @@ void openCatalog(OperationContext* opCtx, const MinVisibleTimestampMap& minVisib
                       str::stream() << "failed to get valid collection pointer for namespace "
                                     << collNss);
 
-            auto uuid = collection->uuid();
-            invariant(uuid);
-
-            if (minVisibleTimestampMap.count(*uuid) > 0) {
-                collection->setMinimumVisibleSnapshot(minVisibleTimestampMap.find(*uuid)->second);
+            if (minVisibleTimestampMap.count(collection->uuid()) > 0) {
+                collection->setMinimumVisibleSnapshot(
+                    minVisibleTimestampMap.find(collection->uuid())->second);
             }
 
             // If this is the oplog collection, re-establish the replication system's cached pointer
diff --git a/src/mongo/db/catalog/coll_mod.cpp b/src/mongo/db/catalog/coll_mod.cpp
index 9aac38954e8..45c57acc17a 100644
--- a/src/mongo/db/catalog/coll_mod.cpp
+++ b/src/mongo/db/catalog/coll_mod.cpp
@@ -268,8 +268,7 @@ Status _collModInternal(OperationContext* opCtx,
     // progress.
     BackgroundOperation::assertNoBgOpInProgForNs(nss);
     if (coll) {
-        IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(
-            coll->uuid().get());
+        IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(coll->uuid());
     }
 
     // If db/collection/view does not exist, short circuit and return.
diff --git a/src/mongo/db/catalog/collection.h b/src/mongo/db/catalog/collection.h
index 15057e3124d..750d2ea9411 100644
--- a/src/mongo/db/catalog/collection.h
+++ b/src/mongo/db/catalog/collection.h
@@ -206,7 +206,7 @@ public:
      */
     virtual void setNs(NamespaceString nss) = 0;
 
-    virtual OptionalCollectionUUID uuid() const = 0;
+    virtual UUID uuid() const = 0;
 
     virtual const IndexCatalog* getIndexCatalog() const = 0;
     virtual IndexCatalog* getIndexCatalog() = 0;
diff --git a/src/mongo/db/catalog/collection_catalog_test.cpp b/src/mongo/db/catalog/collection_catalog_test.cpp
index 32bf6ab8047..e9985074fd8 100644
--- a/src/mongo/db/catalog/collection_catalog_test.cpp
+++ b/src/mongo/db/catalog/collection_catalog_test.cpp
@@ -271,7 +271,7 @@ public:
             auto coll = std::make_unique<CollectionMock>(nss);
             auto uuid = coll->uuid();
 
-            catalog.registerCollection(uuid.get(), std::move(coll));
+            catalog.registerCollection(uuid, std::move(coll));
         }
 
         int numEntries = 0;
@@ -289,7 +289,7 @@ public:
     void tearDown() {
         for (auto it = catalog.begin("resourceDb"); it != catalog.end(); ++it) {
             auto coll = *it;
-            auto uuid = coll->uuid().get();
+            auto uuid = coll->uuid();
             if (!coll) {
                 break;
             }
@@ -358,7 +358,7 @@ TEST_F(CollectionCatalogResourceTest, LookupMissingCollectionResource) {
 TEST_F(CollectionCatalogResourceTest, RemoveCollection) {
     const std::string collNs = "resourceDb.coll1";
     auto coll = catalog.lookupCollectionByNamespace(NamespaceString(collNs));
-    catalog.deregisterCollection(coll->uuid().get());
+    catalog.deregisterCollection(coll->uuid());
     auto rid = ResourceId(RESOURCE_COLLECTION, collNs);
     ASSERT(!catalog.lookupResourceName(rid));
 }
diff --git a/src/mongo/db/catalog/collection_compact.cpp b/src/mongo/db/catalog/collection_compact.cpp
index ab41a04327c..eae4770532d 100644
--- a/src/mongo/db/catalog/collection_compact.cpp
+++ b/src/mongo/db/catalog/collection_compact.cpp
@@ -127,7 +127,7 @@ StatusWith<CompactStats> compactCollection(OperationContext* opCtx,
 
     // If the storage engine doesn't support compacting in place, make sure no background operations
     // or indexes are running.
-    const UUID collectionUUID = collection->uuid().get();
+    const UUID collectionUUID = collection->uuid();
     BackgroundOperation::assertNoBgOpInProgForNs(collectionNss);
     IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(collectionUUID);
 
diff --git a/src/mongo/db/catalog/collection_impl.cpp b/src/mongo/db/catalog/collection_impl.cpp
index fdde33beeb5..f9a02f46309 100644
--- a/src/mongo/db/catalog/collection_impl.cpp
+++ b/src/mongo/db/catalog/collection_impl.cpp
@@ -196,7 +196,7 @@ using logger::LogComponent;
 
 CollectionImpl::CollectionImpl(OperationContext* opCtx,
                                const NamespaceString& nss,
-                               OptionalCollectionUUID uuid,
+                               UUID uuid,
                                std::unique_ptr<RecordStore> recordStore)
     : _magic(kMagicNumber),
       _ns(nss),
@@ -324,13 +324,15 @@ StatusWithMatchExpression CollectionImpl::parseValidator(
     if (ns().isSystem() && !ns().isDropPendingNamespace()) {
         return {ErrorCodes::InvalidOptions,
                 str::stream() << "Document validators not allowed on system collection " << ns()
-                              << (_uuid ? " with UUID " + _uuid->toString() : "")};
+                              << " with UUID "
+                              << _uuid};
     }
 
     if (ns().isOnInternalDb()) {
         return {ErrorCodes::InvalidOptions,
                 str::stream() << "Document validators are not allowed on collection " << ns().ns()
-                              << (_uuid ? " with UUID " + _uuid->toString() : "")
+                              << " with UUID "
+                              << _uuid
                               << " in the "
                               << ns().db()
                               << " internal database"};
@@ -701,8 +703,7 @@ RecordId CollectionImpl::updateDocument(OperationContext* opCtx,
     invariant(sid == opCtx->recoveryUnit()->getSnapshotId());
     args->updatedDoc = newDoc;
 
-    invariant(uuid());
-    OplogUpdateEntryArgs entryArgs(*args, ns(), *uuid());
+    OplogUpdateEntryArgs entryArgs(*args, ns(), _uuid);
     getGlobalServiceContext()->getOpObserver()->onUpdate(opCtx, entryArgs);
 
     return {oldLocation};
@@ -732,8 +733,7 @@ StatusWith<RecordData> CollectionImpl::updateDocumentWithDamages(
     if (newRecStatus.isOK()) {
         args->updatedDoc = newRecStatus.getValue().toBson();
 
-        invariant(uuid());
-        OplogUpdateEntryArgs entryArgs(*args, ns(), *uuid());
+        OplogUpdateEntryArgs entryArgs(*args, ns(), _uuid);
         getGlobalServiceContext()->getOpObserver()->onUpdate(opCtx, entryArgs);
     }
     return newRecStatus;
@@ -1285,7 +1285,7 @@ void _validateCatalogEntry(OperationContext* opCtx,
                            BSONObj validatorDoc,
                            ValidateResults* results) {
     CollectionOptions options = DurableCatalog::get(opCtx)->getCollectionOptions(opCtx, coll->ns());
-    addErrorIfUnequal(options.uuid, coll->uuid(), "UUID", results);
+    addErrorIfUnequal(*options.uuid, coll->uuid(), "UUID", results);
     const CollatorInterface* collation = coll->getDefaultCollator();
     addErrorIfUnequal(options.collation.isEmpty(), !collation, "simple collation", results);
     if (!options.collation.isEmpty() && collation)
@@ -1333,8 +1333,7 @@ Status CollectionImpl::validate(OperationContext* opCtx,
             opCtx, &indexConsistency, level, _indexCatalog.get(), &indexNsResultsMap);
 
         // Validate the record store
-        std::string uuidString = str::stream()
-            << " (UUID: " << (uuid() ? uuid()->toString() : "none") << ")";
+        std::string uuidString = str::stream() << " (UUID: " << _uuid << ")";
         log(LogComponent::kIndex) << "validating collection " << ns() << uuidString;
         _validateRecordStore(
             opCtx, _recordStore.get(), level, background, &indexValidator, results, output);
diff --git a/src/mongo/db/catalog/collection_impl.h b/src/mongo/db/catalog/collection_impl.h
index a9a2c6fbfde..46b56f805e1 100644
--- a/src/mongo/db/catalog/collection_impl.h
+++ b/src/mongo/db/catalog/collection_impl.h
@@ -47,7 +47,7 @@ public:
 
     explicit CollectionImpl(OperationContext* opCtx,
                             const NamespaceString& nss,
-                            OptionalCollectionUUID uuid,
+                            UUID uuid,
                             std::unique_ptr<RecordStore> recordStore);
 
     ~CollectionImpl();
@@ -78,7 +78,7 @@ public:
 
     void setNs(NamespaceString nss) final;
 
-    OptionalCollectionUUID uuid() const {
+    UUID uuid() const {
         return _uuid;
     }
 
@@ -389,7 +389,7 @@ private:
     int _magic;
 
     NamespaceString _ns;
-    OptionalCollectionUUID _uuid;
+    UUID _uuid;
 
     // The RecordStore may be null during a repair operation.
     std::unique_ptr<RecordStore> _recordStore;  // owned
diff --git a/src/mongo/db/catalog/collection_mock.h b/src/mongo/db/catalog/collection_mock.h
index cb78c52b72f..19eb457bd7a 100644
--- a/src/mongo/db/catalog/collection_mock.h
+++ b/src/mongo/db/catalog/collection_mock.h
@@ -273,7 +273,7 @@ public:
         std::abort();
     }
 
-    OptionalCollectionUUID uuid() const {
+    UUID uuid() const {
         return _uuid;
     }
 
@@ -282,7 +282,7 @@ public:
     }
 
 private:
-    OptionalCollectionUUID _uuid = UUID::gen();
+    UUID _uuid = UUID::gen();
     NamespaceString _ns;
     std::unique_ptr<IndexCatalog> _indexCatalog;
 };
diff --git a/src/mongo/db/catalog/database_impl.cpp b/src/mongo/db/catalog/database_impl.cpp
index 1388714f3f7..d5c57cc8db4 100644
--- a/src/mongo/db/catalog/database_impl.cpp
+++ b/src/mongo/db/catalog/database_impl.cpp
@@ -348,13 +348,12 @@ Status DatabaseImpl::dropCollectionEvenIfSystem(OperationContext* opCtx,
     auto numRecords = collection->numRecords(opCtx);
 
     auto uuid = collection->uuid();
-    auto uuidString = uuid ? uuid.get().toString() : "no UUID";
 
     // Make sure no indexes builds are in progress.
     // Use massert() to be consistent with IndexCatalog::dropAllIndexes().
     auto numIndexesInProgress = collection->getIndexCatalog()->numIndexesInProgress(opCtx);
     massert(ErrorCodes::BackgroundOperationInProgressForNamespace,
-            str::stream() << "cannot drop collection " << nss << " (" << uuidString << ") when "
+            str::stream() << "cannot drop collection " << nss << " (" << uuid << ") when "
                           << numIndexesInProgress
                           << " index builds in progress.",
             numIndexesInProgress == 0);
@@ -385,7 +384,7 @@ Status DatabaseImpl::dropCollectionEvenIfSystem(OperationContext* opCtx,
         _dropCollectionIndexes(opCtx, nss, collection);
 
         auto commitTimestamp = opCtx->recoveryUnit()->getCommitTimestamp();
-        log() << "dropCollection: " << nss << " (" << uuidString
+        log() << "dropCollection: " << nss << " (" << uuid
               << ") - storage engine will take ownership of drop-pending collection with optime "
               << dropOpTime << " and commit timestamp " << commitTimestamp;
         if (dropOpTime.isNull()) {
@@ -425,7 +424,7 @@ Status DatabaseImpl::dropCollectionEvenIfSystem(OperationContext* opCtx,
     // Rename collection using drop-pending namespace generated from drop optime.
     auto dpns = nss.makeDropPendingNamespace(dropOpTime);
     const bool stayTemp = true;
-    log() << "dropCollection: " << nss << " (" << uuidString
+    log() << "dropCollection: " << nss << " (" << uuid
           << ") - renaming to drop-pending collection: " << dpns << " with drop optime "
           << dropOpTime;
     {
@@ -454,7 +453,7 @@ void DatabaseImpl::_dropCollectionIndexes(OperationContext* opCtx,
 Status DatabaseImpl::_finishDropCollection(OperationContext* opCtx,
                                            const NamespaceString& nss,
                                            Collection* collection) const {
-    UUID uuid = *collection->uuid();
+    UUID uuid = collection->uuid();
     log() << "Finishing collection drop for " << nss << " (" << uuid << ").";
 
     auto status = DurableCatalog::get(opCtx)->dropCollection(opCtx, nss);
@@ -507,8 +506,8 @@ Status DatabaseImpl::renameCollection(OperationContext* opCtx,
                           << toNss);
     }
 
-    log() << "renameCollection: renaming collection " << collToRename->uuid()->toString()
-          << " from " << fromNss << " to " << toNss;
+    log() << "renameCollection: renaming collection " << collToRename->uuid() << " from " << fromNss
+          << " to " << toNss;
 
     Top::get(opCtx->getServiceContext()).collectionDropped(fromNss);
 
@@ -651,7 +650,7 @@ Collection* DatabaseImpl::createCollection(OperationContext* opCtx,
     });
 
     auto& catalog = CollectionCatalog::get(opCtx);
-    auto uuid = ownedCollection->uuid().get();
+    auto uuid = ownedCollection->uuid();
     catalog.registerCollection(uuid, std::move(ownedCollection));
     opCtx->recoveryUnit()->onRollback([uuid, &catalog] { catalog.deregisterCollection(uuid); });
 
diff --git a/src/mongo/db/catalog/drop_collection.cpp b/src/mongo/db/catalog/drop_collection.cpp
index 5a8c2828f63..b5f30ae2a3e 100644
--- a/src/mongo/db/catalog/drop_collection.cpp
+++ b/src/mongo/db/catalog/drop_collection.cpp
@@ -130,7 +130,7 @@ Status _dropCollection(OperationContext* opCtx,
 
     int numIndexes = coll->getIndexCatalog()->numIndexesTotal(opCtx);
     BackgroundOperation::assertNoBgOpInProgForNs(collectionName.ns());
-    IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(coll->uuid().get());
+    IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(coll->uuid());
     Status status =
         systemCollectionMode == DropCollectionSystemCollectionMode::kDisallowSystemCollectionDrops
         ? db->dropCollection(opCtx, collectionName, dropOpTime)
diff --git a/src/mongo/db/catalog/drop_database.cpp b/src/mongo/db/catalog/drop_database.cpp
index 2602c6e59d5..fd471f8ad50 100644
--- a/src/mongo/db/catalog/drop_database.cpp
+++ b/src/mongo/db/catalog/drop_database.cpp
@@ -189,7 +189,7 @@ Status dropDatabase(OperationContext* opCtx, const std::string& dbName) {
 
             BackgroundOperation::assertNoBgOpInProgForNs(nss.ns());
             IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(
-                db->getCollection(opCtx, nss)->uuid().get());
+                db->getCollection(opCtx, nss)->uuid());
 
             writeConflictRetry(opCtx, "dropDatabase_collection", nss.ns(), [&] {
                 WriteUnitOfWork wunit(opCtx);
diff --git a/src/mongo/db/catalog/drop_indexes.cpp b/src/mongo/db/catalog/drop_indexes.cpp
index b74a55f00cf..cd56e85e2b6 100644
--- a/src/mongo/db/catalog/drop_indexes.cpp
+++ b/src/mongo/db/catalog/drop_indexes.cpp
@@ -228,7 +228,7 @@ Status dropIndexes(OperationContext* opCtx,
 
         BackgroundOperation::assertNoBgOpInProgForNs(nss);
         IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(
-            collection->uuid().get());
+            collection->uuid());
 
         WriteUnitOfWork wunit(opCtx);
         OldClientContext ctx(opCtx, nss.ns());
diff --git a/src/mongo/db/catalog/index_builds_manager.cpp b/src/mongo/db/catalog/index_builds_manager.cpp
index cbc9217ee12..fe816ce7dc4 100644
--- a/src/mongo/db/catalog/index_builds_manager.cpp
+++ b/src/mongo/db/catalog/index_builds_manager.cpp
@@ -112,7 +112,7 @@ Status IndexBuildsManager::setUpIndexBuild(OperationContext* opCtx,
               << ": indexes: " << indexes.size();
     } else {
         log() << "Index build initialized: " << buildUUID << ": " << nss << " ("
-              << *collection->uuid() << " ): indexes: " << indexes.size();
+              << collection->uuid() << " ): indexes: " << indexes.size();
     }
 
     return Status::OK();
diff --git a/src/mongo/db/catalog/index_catalog_impl.cpp b/src/mongo/db/catalog/index_catalog_impl.cpp
index a0a467bccc2..571a5705201 100644
--- a/src/mongo/db/catalog/index_catalog_impl.cpp
+++ b/src/mongo/db/catalog/index_catalog_impl.cpp
@@ -1064,9 +1064,7 @@ int IndexCatalogImpl::numIndexesReady(OperationContext* opCtx) const {
                 log() << "  index: " << i;
             }
 
-            if (_collection->uuid()) {
-                log() << "collection uuid: " << _collection->uuid();
-            }
+            log() << "collection uuid: " << _collection->uuid();
 
             invariant(itIndexes.size() == completedIndexes.size(),
                       "The number of ready indexes reported in the collection metadata catalog did "
diff --git a/src/mongo/db/catalog/multi_index_block.cpp b/src/mongo/db/catalog/multi_index_block.cpp
index 6bb769f533a..c3065c1a13b 100644
--- a/src/mongo/db/catalog/multi_index_block.cpp
+++ b/src/mongo/db/catalog/multi_index_block.cpp
@@ -77,7 +77,7 @@ void MultiIndexBlock::cleanUpAfterBuild(OperationContext* opCtx, Collection* col
     if (_collectionUUID) {
         // init() was previously called with a collection pointer, so ensure that the same
         // collection is being provided for clean up and the interface in not being abused.
-        invariant(_collectionUUID.get() == collection->uuid().get());
+        invariant(_collectionUUID.get() == collection->uuid());
     }
 
     if (!_needToCleanup && !_indexes.empty()) {
@@ -201,18 +201,15 @@ StatusWith<std::vector<BSONObj>> MultiIndexBlock::init(OperationContext* opCtx,
                 str::stream() << "Index build aborted: " << _abortReason
                               << ". Cannot initialize index builder: "
                               << collection->ns()
-                              << (collection->uuid()
-                                      ? (" (" + collection->uuid()->toString() + "): ")
-                                      : ": ")
+                              << " ("
+                              << collection->uuid()
+                              << "): "
                               << indexSpecs.size()
                               << " provided. First index spec: "
                               << (indexSpecs.empty() ? BSONObj() : indexSpecs[0])};
     }
 
-    // UUIDs are not guaranteed during startup because the check happens after indexes are rebuilt.
-    if (collection->uuid()) {
-        _collectionUUID = collection->uuid().get();
-    }
+    _collectionUUID = collection->uuid();
 
     _buildIsCleanedUp = false;
 
@@ -366,7 +363,7 @@ Status MultiIndexBlock::insertAllDocumentsInCollection(OperationContext* opCtx,
 
     // UUIDs are not guaranteed during startup because the check happens after indexes are rebuilt.
     if (_collectionUUID) {
-        invariant(_collectionUUID.get() == collection->uuid().get());
+        invariant(_collectionUUID.get() == collection->uuid());
     }
 
     // Refrain from persisting any multikey updates as a result from building the index. Instead,
@@ -707,7 +704,7 @@ Status MultiIndexBlock::commit(OperationContext* opCtx,
                                OnCommitFn onCommit) {
     // UUIDs are not guaranteed during startup because the check happens after indexes are rebuilt.
     if (_collectionUUID) {
-        invariant(_collectionUUID.get() == collection->uuid().get());
+        invariant(_collectionUUID.get() == collection->uuid());
     }
 
     if (State::kAborted == _getState()) {
diff --git a/src/mongo/db/catalog/rename_collection.cpp b/src/mongo/db/catalog/rename_collection.cpp
index 2492fbac0d4..08047b91a31 100644
--- a/src/mongo/db/catalog/rename_collection.cpp
+++ b/src/mongo/db/catalog/rename_collection.cpp
@@ -117,8 +117,7 @@ Status checkSourceAndTargetNamespaces(OperationContext* opCtx,
     }
 
     BackgroundOperation::assertNoBgOpInProgForNs(source.ns());
-    IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(
-        sourceColl->uuid().get());
+    IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(sourceColl->uuid());
 
     Collection* targetColl = db->getCollection(opCtx, target);
 
@@ -255,7 +254,7 @@ Status renameCollectionAndDropTarget(OperationContext* opCtx,
 
         BackgroundOperation::assertNoBgOpInProgForNs(targetColl->ns().ns());
         IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(
-            targetColl->uuid().get());
+            targetColl->uuid());
 
         auto status = db->dropCollection(opCtx, targetColl->ns(), renameOpTime);
         if (!status.isOK())
@@ -381,7 +380,7 @@ Status renameCollectionWithinDBForApplyOps(OperationContext* opCtx,
         if (uuidToDrop && uuidToDrop != targetColl->uuid()) {
             // We need to rename the targetColl to a temporary name.
             auto status = renameTargetCollectionToTmp(
-                opCtx, source, sourceColl->uuid().get(), db, target, targetColl->uuid().get());
+                opCtx, source, sourceColl->uuid(), db, target, targetColl->uuid());
             if (!status.isOK())
                 return status;
             targetColl = nullptr;
@@ -462,8 +461,7 @@ Status renameBetweenDBs(OperationContext* opCtx,
                 "Cannot rename collections between a replicated and an unreplicated database"};
 
     BackgroundOperation::assertNoBgOpInProgForNs(source.ns());
-    IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(
-        sourceColl->uuid().get());
+    IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(sourceColl->uuid());
 
     auto targetDB = DatabaseHolder::get(opCtx)->getDb(opCtx, target.db());
 
@@ -585,7 +583,7 @@ Status renameBetweenDBs(OperationContext* opCtx,
             for (const auto& indexToCopy : indexesToCopy) {
                 opObserver->onCreateIndex(opCtx,
                                           tmpName,
-                                          *(tmpColl->uuid()),
+                                          tmpColl->uuid(),
                                           indexToCopy,
                                           false  // fromMigrate
                                           );
diff --git a/src/mongo/db/catalog/rename_collection_test.cpp b/src/mongo/db/catalog/rename_collection_test.cpp
index 0b9c2d1639d..903461b9133 100644
--- a/src/mongo/db/catalog/rename_collection_test.cpp
+++ b/src/mongo/db/catalog/rename_collection_test.cpp
@@ -1163,9 +1163,9 @@ TEST_F(RenameCollectionTest, CollectionCatalogMappingRemainsIntactThroughRename)
     auto& catalog = CollectionCatalog::get(_opCtx.get());
     Collection* sourceColl = _getCollection_inlock(_opCtx.get(), _sourceNss);
     ASSERT(sourceColl);
-    ASSERT_EQ(sourceColl, catalog.lookupCollectionByUUID(*sourceColl->uuid()));
+    ASSERT_EQ(sourceColl, catalog.lookupCollectionByUUID(sourceColl->uuid()));
     ASSERT_OK(renameCollection(_opCtx.get(), _sourceNss, _targetNss, {}));
-    ASSERT_EQ(sourceColl, catalog.lookupCollectionByUUID(*sourceColl->uuid()));
+    ASSERT_EQ(sourceColl, catalog.lookupCollectionByUUID(sourceColl->uuid()));
 }
 
 TEST_F(RenameCollectionTest, FailRenameCollectionFromReplicatedToUnreplicatedDB) {
diff --git a/src/mongo/db/cloner.cpp b/src/mongo/db/cloner.cpp
index 3ddd265ea1e..4656d7b379a 100644
--- a/src/mongo/db/cloner.cpp
+++ b/src/mongo/db/cloner.cpp
@@ -418,7 +418,7 @@ void Cloner::copyIndexes(OperationContext* opCtx,
     if (opCtx->writesAreReplicated()) {
         for (auto&& infoObj : indexInfoObjs) {
             getGlobalServiceContext()->getOpObserver()->onCreateIndex(
-                opCtx, collection->ns(), *(collection->uuid()), infoObj, false);
+                opCtx, collection->ns(), collection->uuid(), infoObj, false);
         }
     }
     wunit.commit();
diff --git a/src/mongo/db/commands/create_indexes.cpp b/src/mongo/db/commands/create_indexes.cpp
index c34aebd5bc6..6d0a870a691 100644
--- a/src/mongo/db/commands/create_indexes.cpp
+++ b/src/mongo/db/commands/create_indexes.cpp
@@ -581,7 +581,7 @@ bool runCreateIndexes(OperationContext* opCtx,
                            collection,
                            [opCtx, &ns, collection](const BSONObj& spec) {
                                opCtx->getServiceContext()->getOpObserver()->onCreateIndex(
-                                   opCtx, ns, *(collection->uuid()), spec, false);
+                                   opCtx, ns, collection->uuid(), spec, false);
                            },
                            MultiIndexBlock::kNoopOnCommitFn));
 
diff --git a/src/mongo/db/commands/dbcheck.cpp b/src/mongo/db/commands/dbcheck.cpp
index 6cbfc7b6bf9..484cac84eb9 100644
--- a/src/mongo/db/commands/dbcheck.cpp
+++ b/src/mongo/db/commands/dbcheck.cpp
@@ -339,12 +339,6 @@ private:
             return false;
         }
 
-        auto uuid = collection->uuid();
-        // Check if UUID exists.
-        if (!uuid) {
-            return false;
-        }
-
         auto[prev, next] = getPrevAndNextUUIDs(opCtx, collection);
 
         // Find and report collection metadata.
@@ -353,7 +347,7 @@ private:
 
         DbCheckOplogCollection entry;
         entry.setNss(collection->ns());
-        entry.setUuid(*collection->uuid());
+        entry.setUuid(collection->uuid());
         if (prev) {
             entry.setPrev(*prev);
         }
@@ -375,7 +369,7 @@ private:
         collectionInfo.options = entry.getOptions();
 
         auto hle = dbCheckCollectionEntry(
-            collection->ns(), *collection->uuid(), collectionInfo, collectionInfo, optime);
+            collection->ns(), collection->uuid(), collectionInfo, collectionInfo, optime);
 
         HealthLog::get(opCtx).log(*hle);
 
diff --git a/src/mongo/db/commands/drop_indexes.cpp b/src/mongo/db/commands/drop_indexes.cpp
index 1b4b9491d7f..25702078378 100644
--- a/src/mongo/db/commands/drop_indexes.cpp
+++ b/src/mongo/db/commands/drop_indexes.cpp
@@ -145,9 +145,8 @@ public:
         }
 
         BackgroundOperation::assertNoBgOpInProgForNs(toReIndexNss.ns());
-        invariant(collection->uuid());
         IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(
-            collection->uuid().get());
+            collection->uuid());
 
         // This is necessary to set up CurOp and update the Top stats.
         OldClientContext ctx(opCtx, toReIndexNss.ns());
diff --git a/src/mongo/db/commands/mr.cpp b/src/mongo/db/commands/mr.cpp
index 244acfbd221..7d0d52be379 100644
--- a/src/mongo/db/commands/mr.cpp
+++ b/src/mongo/db/commands/mr.cpp
@@ -190,7 +190,7 @@ void dropTempCollections(OperationContext* cleanupOpCtx,
                                     ->canAcceptWritesFor(cleanupOpCtx, tempNamespace));
                         BackgroundOperation::assertNoBgOpInProgForNs(tempNamespace.ns());
                         IndexBuildsCoordinator::get(cleanupOpCtx)
-                            ->assertNoIndexBuildInProgForCollection(collection->uuid().get());
+                            ->assertNoIndexBuildInProgForCollection(collection->uuid());
                         WriteUnitOfWork wunit(cleanupOpCtx);
                         uassertStatusOK(db->dropCollection(cleanupOpCtx, tempNamespace));
                         wunit.commit();
@@ -209,7 +209,7 @@ void dropTempCollections(OperationContext* cleanupOpCtx,
                     if (auto collection = db->getCollection(cleanupOpCtx, incLong)) {
                         BackgroundOperation::assertNoBgOpInProgForNs(incLong.ns());
                         IndexBuildsCoordinator::get(cleanupOpCtx)
-                            ->assertNoIndexBuildInProgForCollection(collection->uuid().get());
+                            ->assertNoIndexBuildInProgForCollection(collection->uuid());
                         WriteUnitOfWork wunit(cleanupOpCtx);
                         uassertStatusOK(db->dropCollection(cleanupOpCtx, incLong));
                         wunit.commit();
@@ -623,7 +623,7 @@ void State::prepTempCollection() {
 
             // Log the createIndex operation.
             _opCtx->getServiceContext()->getOpObserver()->onCreateIndex(
-                _opCtx, _config.tempNamespace, *(tempColl->uuid()), indexToInsert, false);
+                _opCtx, _config.tempNamespace, tempColl->uuid(), indexToInsert, false);
         }
         wuow.commit();
 
diff --git a/src/mongo/db/commands/run_aggregate.cpp b/src/mongo/db/commands/run_aggregate.cpp
index ab63dec4dbe..7293a0b01cb 100644
--- a/src/mongo/db/commands/run_aggregate.cpp
+++ b/src/mongo/db/commands/run_aggregate.cpp
@@ -571,7 +571,9 @@ Status runAggregate(OperationContext* opCtx,
             // This is a regular aggregation. Lock the collection or view.
             ctx.emplace(opCtx, nss, AutoGetCollection::ViewMode::kViewsPermitted);
             collatorToUse.emplace(resolveCollator(opCtx, request, ctx->getCollection()));
-            uuid = ctx->getCollection() ? ctx->getCollection()->uuid() : boost::none;
+            if (ctx->getCollection()) {
+                uuid = ctx->getCollection()->uuid();
+            }
         }
 
         Collection* collection = ctx ? ctx->getCollection() : nullptr;
diff --git a/src/mongo/db/commands/test_commands.cpp b/src/mongo/db/commands/test_commands.cpp
index 51373ac0841..f11cb7c1bd4 100644
--- a/src/mongo/db/commands/test_commands.cpp
+++ b/src/mongo/db/commands/test_commands.cpp
@@ -172,7 +172,7 @@ public:
 
         BackgroundOperation::assertNoBgOpInProgForNs(fullNs.ns());
         IndexBuildsCoordinator::get(opCtx)->assertNoIndexBuildInProgForCollection(
-            collection->uuid().get());
+            collection->uuid());
 
         collection->cappedTruncateAfter(opCtx, end, inc);
 
diff --git a/src/mongo/db/exec/requires_collection_stage.h b/src/mongo/db/exec/requires_collection_stage.h
index 677336e1fb2..896d9eb5181 100644
--- a/src/mongo/db/exec/requires_collection_stage.h
+++ b/src/mongo/db/exec/requires_collection_stage.h
@@ -58,7 +58,7 @@ public:
     RequiresCollectionStageBase(const char* stageType, OperationContext* opCtx, CollectionT coll)
         : PlanStage(stageType, opCtx),
           _collection(coll),
-          _collectionUUID(_collection->uuid().get()),
+          _collectionUUID(_collection->uuid()),
           _databaseEpoch(getDatabaseEpoch(_collection)),
           _nss(_collection->ns()) {
         invariant(_collection);
diff --git a/src/mongo/db/index_builder.cpp b/src/mongo/db/index_builder.cpp
index 6f5804d17c4..c741814a663 100644
--- a/src/mongo/db/index_builder.cpp
+++ b/src/mongo/db/index_builder.cpp
@@ -182,7 +182,7 @@ Status IndexBuilder::_build(OperationContext* opCtx,
                                      coll,
                                      [opCtx, coll, &ns](const BSONObj& indexSpec) {
                                          opCtx->getServiceContext()->getOpObserver()->onCreateIndex(
-                                             opCtx, ns, *(coll->uuid()), indexSpec, false);
+                                             opCtx, ns, coll->uuid(), indexSpec, false);
                                      },
                                      MultiIndexBlock::kNoopOnCommitFn);
         if (!status.isOK()) {
diff --git a/src/mongo/db/index_builds_coordinator_mongod.cpp b/src/mongo/db/index_builds_coordinator_mongod.cpp
index baba0f332ff..a0e20599e65 100644
--- a/src/mongo/db/index_builds_coordinator_mongod.cpp
+++ b/src/mongo/db/index_builds_coordinator_mongod.cpp
@@ -247,7 +247,7 @@ Status IndexBuildsCoordinatorMongod::setCommitQuorum(OperationContext* opCtx,
                       str::stream() << "Collection '" << nss << "' was not found.");
     }
 
-    UUID collectionUUID = *collection->uuid();
+    UUID collectionUUID = collection->uuid();
 
     stdx::unique_lock<stdx::mutex> lk(_mutex);
     auto collectionIt = _collectionIndexBuilds.find(collectionUUID);
diff --git a/src/mongo/db/op_observer_impl.cpp b/src/mongo/db/op_observer_impl.cpp
index 870c10a7c1f..ca72ef06a95 100644
--- a/src/mongo/db/op_observer_impl.cpp
+++ b/src/mongo/db/op_observer_impl.cpp
@@ -623,7 +623,6 @@ void OpObserverImpl::onCollMod(OperationContext* opCtx,
     }
     Collection* coll = db->getCollection(opCtx, nss);
 
-    invariant(coll->uuid());
     invariant(coll->uuid() == uuid);
     invariant(DurableCatalog::get(opCtx)->isEqualToMetadataUUID(opCtx, nss, uuid));
 }
diff --git a/src/mongo/db/repair_database_and_check_version.cpp b/src/mongo/db/repair_database_and_check_version.cpp
index f9f2bdb64bb..609db294b31 100644
--- a/src/mongo/db/repair_database_and_check_version.cpp
+++ b/src/mongo/db/repair_database_and_check_version.cpp
@@ -208,12 +208,6 @@ Status ensureCollectionProperties(OperationContext* opCtx,
                 break;
             }
 
-            // We expect all collections to have UUIDs in MongoDB 4.2
-            if (!coll->uuid()) {
-                error() << "collection " << coll->ns() << " is missing a UUID";
-                return downgradeError;
-            }
-
             // All user-created replicated collections created since MongoDB 4.0 have _id indexes.
             auto requiresIndex = coll->requiresIdIndex() && coll->ns().isReplicated();
             auto collOptions = DurableCatalog::get(opCtx)->getCollectionOptions(opCtx, coll->ns());
diff --git a/src/mongo/db/repl/apply_ops.cpp b/src/mongo/db/repl/apply_ops.cpp
index 54971bbdee8..df72f0faea8 100644
--- a/src/mongo/db/repl/apply_ops.cpp
+++ b/src/mongo/db/repl/apply_ops.cpp
@@ -183,7 +183,7 @@ Status _applyOps(OperationContext* opCtx,
 
             // Append completed op, including UUID if available, to 'opsBuilder'.
             if (opsBuilder) {
-                if (opObj.hasField("ui") || !(collection && collection->uuid())) {
+                if (opObj.hasField("ui") || !collection) {
                     // No changes needed to operation document.
                     opsBuilder->append(opObj);
                 } else {
@@ -191,7 +191,7 @@ Status _applyOps(OperationContext* opCtx,
                     auto uuid = collection->uuid();
                     BSONObjBuilder opBuilder;
                     opBuilder.appendElements(opObj);
-                    uuid->appendToBuilder(&opBuilder, "ui");
+                    uuid.appendToBuilder(&opBuilder, "ui");
                     opsBuilder->append(opBuilder.obj());
                 }
             }
diff --git a/src/mongo/db/repl/dbcheck.cpp b/src/mongo/db/repl/dbcheck.cpp
index 8a3827db897..cd546957b8d 100644
--- a/src/mongo/db/repl/dbcheck.cpp
+++ b/src/mongo/db/repl/dbcheck.cpp
@@ -241,7 +241,7 @@ std::string hashCollectionInfo(const DbCheckCollectionInformation& info) {
 std::pair<boost::optional<UUID>, boost::optional<UUID>> getPrevAndNextUUIDs(
     OperationContext* opCtx, Collection* collection) {
     const CollectionCatalog& catalog = CollectionCatalog::get(opCtx);
-    const UUID uuid = *collection->uuid();
+    const UUID uuid = collection->uuid();
 
     std::vector<CollectionUUID> collectionUUIDs =
         catalog.getAllCollectionUUIDsFromDb(collection->ns().db());
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index 5d5b2f16ef5..5ee855adb88 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -268,7 +268,7 @@ void createIndexForApplyOps(OperationContext* opCtx,
         Lock::TempRelease release(opCtx->lockState());
         // TempRelease cannot fail because no recursive locks should be taken.
         invariant(!opCtx->lockState()->isLocked());
-        auto collUUID = *indexCollection->uuid();
+        auto collUUID = indexCollection->uuid();
         auto indexBuildUUID = UUID::gen();
         auto indexBuildsCoordinator = IndexBuildsCoordinator::get(opCtx);
 
diff --git a/src/mongo/db/repl/rollback_test_fixture.h b/src/mongo/db/repl/rollback_test_fixture.h
index 8f03742bfd4..f4c4ce5a13a 100644
--- a/src/mongo/db/repl/rollback_test_fixture.h
+++ b/src/mongo/db/repl/rollback_test_fixture.h
@@ -177,7 +177,7 @@ public:
             nsOrUUID.uuid() == _setCollectionCountStatusUUID) {
             return *_setCollectionCountStatus;
         }
-        _newCounts[nsOrUUID.uuid().get()] = newCount;
+        _newCounts[*nsOrUUID.uuid()] = newCount;
         return Status::OK();
     }
 
diff --git a/src/mongo/db/repl/rs_rollback.cpp b/src/mongo/db/repl/rs_rollback.cpp
index a1b76201cdf..a94dc1c42fb 100644
--- a/src/mongo/db/repl/rs_rollback.cpp
+++ b/src/mongo/db/repl/rs_rollback.cpp
@@ -784,7 +784,7 @@ void dropCollection(OperationContext* opCtx,
         RemoveSaver removeSaver("rollback", "", nss.ns());
         log() << "Rolling back createCollection on " << nss
               << ": Preparing to write documents to a rollback file for a collection " << nss
-              << " with uuid " << *(collection->uuid()) << " to "
+              << " with uuid " << collection->uuid() << " to "
               << removeSaver.file().generic_string();
 
         // Performs a collection scan and writes all documents in the collection to disk
@@ -860,12 +860,12 @@ void renameOutOfTheWay(OperationContext* opCtx, RenameCollectionInfo info, Datab
 
     LOG(2) << "Attempted to rename collection from " << info.renameFrom << " to " << info.renameTo
            << " but " << info.renameTo << " exists already. Temporarily renaming collection "
-           << info.renameTo << " with UUID " << collection->uuid().get() << " out of the way to "
+           << info.renameTo << " with UUID " << collection->uuid() << " out of the way to "
            << tempNss;
 
     // Renaming the collection that was clashing with the attempted rename
     // operation to a different collection name.
-    auto uuid = collection->uuid().get();
+    auto uuid = collection->uuid();
     auto renameStatus = renameCollectionForRollback(opCtx, tempNss, uuid);
 
     if (!renameStatus.isOK()) {
diff --git a/src/mongo/db/repl/rs_rollback_test.cpp b/src/mongo/db/repl/rs_rollback_test.cpp
index 84a3a8d803b..a49055ba339 100644
--- a/src/mongo/db/repl/rs_rollback_test.cpp
+++ b/src/mongo/db/repl/rs_rollback_test.cpp
@@ -89,7 +89,7 @@ OplogInterfaceMock::Operation makeDropIndexOplogEntry(Collection* collection,
         BSON("ts" << Timestamp(Seconds(time), 0) << "op"
                   << "c"
                   << "ui"
-                  << collection->uuid().get()
+                  << collection->uuid()
                   << "ns"
                   << "test.$cmd"
                   << "o"
@@ -116,7 +116,7 @@ OplogInterfaceMock::Operation makeCreateIndexOplogEntry(Collection* collection,
                                     << "ns"
                                     << "test.$cmd"
                                     << "ui"
-                                    << collection->uuid().get()
+                                    << collection->uuid()
                                     << "o"
                                     << indexSpec),
                           RecordId(time));
@@ -385,11 +385,11 @@ TEST_F(RSRollbackTest, RollbackDeleteNoDocumentAtSourceCollectionExistsNonCapped
     options.uuid = UUID::gen();
     auto coll = _createCollection(_opCtx.get(), "test.t", options);
     _testRollbackDelete(
-        _opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid().get(), BSONObj());
+        _opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid(), BSONObj());
     ASSERT_EQUALS(
         0,
         _testRollbackDelete(
-            _opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid().get(), BSONObj()));
+            _opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid(), BSONObj()));
 }
 
 TEST_F(RSRollbackTest, RollbackDeleteNoDocumentAtSourceCollectionExistsCapped) {
@@ -401,7 +401,7 @@ TEST_F(RSRollbackTest, RollbackDeleteNoDocumentAtSourceCollectionExistsCapped) {
     ASSERT_EQUALS(
         0,
         _testRollbackDelete(
-            _opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid().get(), BSONObj()));
+            _opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid(), BSONObj()));
 }
 
 TEST_F(RSRollbackTest, RollbackDeleteRestoreDocument) {
@@ -410,12 +410,10 @@ TEST_F(RSRollbackTest, RollbackDeleteRestoreDocument) {
     options.uuid = UUID::gen();
     auto coll = _createCollection(_opCtx.get(), "test.t", options);
     BSONObj doc = BSON("_id" << 0 << "a" << 1);
-    _testRollbackDelete(
-        _opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid().get(), doc);
-    ASSERT_EQUALS(
-        1,
-        _testRollbackDelete(
-            _opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid().get(), doc));
+    _testRollbackDelete(_opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid(), doc);
+    ASSERT_EQUALS(1,
+                  _testRollbackDelete(
+                      _opCtx.get(), _coordinator, _replicationProcess.get(), coll->uuid(), doc));
 }
 
 TEST_F(RSRollbackTest, RollbackInsertDocumentWithNoId) {
@@ -680,13 +678,8 @@ TEST_F(RSRollbackTest, RollingBackCreateIndexAndRenameWithLongName) {
     // The old collection name plus the index name is not too long, but the new collection name
     // plus the index name is too long.
     auto newName = NamespaceString("test", "collcollcollcollcoll");
-    auto renameCollectionOperation =
-        makeRenameCollectionOplogEntry(newName,
-                                       nss,
-                                       collection->uuid().get(),
-                                       boost::none,
-                                       false,
-                                       OpTime(Timestamp(Seconds(2), 0), 1));
+    auto renameCollectionOperation = makeRenameCollectionOplogEntry(
+        newName, nss, collection->uuid(), boost::none, false, OpTime(Timestamp(Seconds(2), 0), 1));
 
     RollbackSourceMock rollbackSource(std::unique_ptr<OplogInterface>(new OplogInterfaceMock({
         commonOperation,
@@ -796,7 +789,7 @@ TEST_F(RSRollbackTest, RollbackCreateIndexCommandMissingIndexName) {
                                                          << "ns"
                                                          << "test.$cmd"
                                                          << "ui"
-                                                         << collection->uuid().get()
+                                                         << collection->uuid()
                                                          << "o"
                                                          << command),
                                                RecordId(2));
@@ -1028,7 +1021,7 @@ TEST_F(RSRollbackTest, RollbackDropCollectionCommand) {
         std::make_pair(BSON("ts" << dropTime.getTimestamp() << "t" << dropTime.getTerm() << "op"
                                  << "c"
                                  << "ui"
-                                 << coll->uuid().get()
+                                 << coll->uuid()
                                  << "ns"
                                  << "test.t"
                                  << "o"
@@ -1075,7 +1068,7 @@ TEST_F(RSRollbackTest, RollbackRenameCollectionInSameDatabaseCommand) {
     CollectionOptions options;
     options.uuid = UUID::gen();
     auto collection = _createCollection(_opCtx.get(), "test.y", options);
-    UUID collectionUUID = collection->uuid().get();
+    UUID collectionUUID = collection->uuid();
 
     OpTime renameTime = OpTime(Timestamp(2, 0), 5);
 
@@ -1133,7 +1126,7 @@ TEST_F(RSRollbackTest,
 
     // Create the collection and save its UUID.
     auto collection = _createCollection(_opCtx.get(), renameToNss, options);
-    auto collectionUUID = collection->uuid().get();
+    auto collectionUUID = collection->uuid();
 
     class RollbackSourceLocal : public RollbackSourceMock {
     public:
@@ -1186,12 +1179,12 @@ TEST_F(RSRollbackTest, RollbackRenameCollectionInDatabaseWithDropTargetTrueComma
     droppedCollOptions.uuid = UUID::gen();
     auto droppedColl = _createCollection(_opCtx.get(), dpns, droppedCollOptions);
     _dropPendingCollectionReaper->addDropPendingNamespace(dropTime, dpns);
-    auto droppedCollectionUUID = droppedColl->uuid().get();
+    auto droppedCollectionUUID = droppedColl->uuid();
 
     CollectionOptions renamedCollOptions;
     renamedCollOptions.uuid = UUID::gen();
     auto renamedCollection = _createCollection(_opCtx.get(), "test.y", renamedCollOptions);
-    auto renamedCollectionUUID = renamedCollection->uuid().get();
+    auto renamedCollectionUUID = renamedCollection->uuid();
 
     auto commonOperation = makeOpAndRecordId(1);
     auto renameCollectionOperation = makeRenameCollectionOplogEntry(NamespaceString("test.x"),
@@ -1227,11 +1220,11 @@ TEST_F(RSRollbackTest, RollbackRenameCollectionInDatabaseWithDropTargetTrueComma
 
         AutoGetCollectionForReadCommand renamedColl(_opCtx.get(), NamespaceString("test.x"));
         ASSERT_TRUE(renamedColl.getCollection());
-        ASSERT_EQUALS(renamedColl.getCollection()->uuid().get(), renamedCollectionUUID);
+        ASSERT_EQUALS(renamedColl.getCollection()->uuid(), renamedCollectionUUID);
 
         AutoGetCollectionForReadCommand droppedColl(_opCtx.get(), NamespaceString("test.y"));
         ASSERT_TRUE(droppedColl.getCollection());
-        ASSERT_EQUALS(droppedColl.getCollection()->uuid().get(), droppedCollectionUUID);
+        ASSERT_EQUALS(droppedColl.getCollection()->uuid(), droppedCollectionUUID);
     }
 }
 
@@ -1244,10 +1237,10 @@ void _testRollbackRenamingCollectionsToEachOther(OperationContext* opCtx,
     createOplog(opCtx);
 
     auto collection1 = RollbackTest::_createCollection(opCtx, "test.y", coll1Options);
-    auto collection1UUID = collection1->uuid().get();
+    auto collection1UUID = collection1->uuid();
 
     auto collection2 = RollbackTest::_createCollection(opCtx, "test.x", coll2Options);
-    auto collection2UUID = collection2->uuid().get();
+    auto collection2UUID = collection2->uuid();
 
     ASSERT_NOT_EQUALS(collection1UUID, collection2UUID);
 
@@ -1291,11 +1284,11 @@ void _testRollbackRenamingCollectionsToEachOther(OperationContext* opCtx,
 
         AutoGetCollectionForReadCommand coll1(opCtx, NamespaceString("test.x"));
         ASSERT_TRUE(coll1.getCollection());
-        ASSERT_EQUALS(coll1.getCollection()->uuid().get(), collection1UUID);
+        ASSERT_EQUALS(coll1.getCollection()->uuid(), collection1UUID);
 
         AutoGetCollectionForReadCommand coll2(opCtx, NamespaceString("test.y"));
         ASSERT_TRUE(coll2.getCollection());
-        ASSERT_EQUALS(coll2.getCollection()->uuid().get(), collection2UUID);
+        ASSERT_EQUALS(coll2.getCollection()->uuid(), collection2UUID);
     }
 }
 
@@ -1336,14 +1329,14 @@ TEST_F(RSRollbackTest, RollbackDropCollectionThenRenameCollectionToDroppedCollec
     CollectionOptions renamedCollOptions;
     renamedCollOptions.uuid = UUID::gen();
     auto renamedCollection = _createCollection(_opCtx.get(), "test.x", renamedCollOptions);
-    auto renamedCollectionUUID = renamedCollection->uuid().get();
+    auto renamedCollectionUUID = renamedCollection->uuid();
 
     OpTime dropTime = OpTime(Timestamp(2, 0), 5);
     auto dpns = NamespaceString("test.x").makeDropPendingNamespace(dropTime);
     CollectionOptions droppedCollOptions;
     droppedCollOptions.uuid = UUID::gen();
     auto droppedCollection = _createCollection(_opCtx.get(), dpns, droppedCollOptions);
-    auto droppedCollectionUUID = droppedCollection->uuid().get();
+    auto droppedCollectionUUID = droppedCollection->uuid();
     _dropPendingCollectionReaper->addDropPendingNamespace(dropTime, dpns);
 
     auto commonOperation = makeOpAndRecordId(1);
@@ -1393,11 +1386,11 @@ TEST_F(RSRollbackTest, RollbackDropCollectionThenRenameCollectionToDroppedCollec
 
         AutoGetCollectionForReadCommand autoCollX(_opCtx.get(), NamespaceString("test.x"));
         ASSERT_TRUE(autoCollX.getCollection());
-        ASSERT_EQUALS(autoCollX.getCollection()->uuid().get(), droppedCollectionUUID);
+        ASSERT_EQUALS(autoCollX.getCollection()->uuid(), droppedCollectionUUID);
 
         AutoGetCollectionForReadCommand autoCollY(_opCtx.get(), NamespaceString("test.y"));
         ASSERT_TRUE(autoCollY.getCollection());
-        ASSERT_EQUALS(autoCollY.getCollection()->uuid().get(), renamedCollectionUUID);
+        ASSERT_EQUALS(autoCollY.getCollection()->uuid(), renamedCollectionUUID);
     }
 }
 
@@ -1407,12 +1400,12 @@ TEST_F(RSRollbackTest, RollbackRenameCollectionThenCreateNewCollectionWithOldNam
     CollectionOptions renamedCollOptions;
     renamedCollOptions.uuid = UUID::gen();
     auto renamedCollection = _createCollection(_opCtx.get(), "test.y", renamedCollOptions);
-    auto renamedCollectionUUID = renamedCollection->uuid().get();
+    auto renamedCollectionUUID = renamedCollection->uuid();
 
     CollectionOptions createdCollOptions;
     createdCollOptions.uuid = UUID::gen();
     auto createdCollection = _createCollection(_opCtx.get(), "test.x", createdCollOptions);
-    auto createdCollectionUUID = createdCollection->uuid().get();
+    auto createdCollectionUUID = createdCollection->uuid();
 
     auto commonOperation = makeOpAndRecordId(1);
 
@@ -1457,7 +1450,7 @@ TEST_F(RSRollbackTest, RollbackRenameCollectionThenCreateNewCollectionWithOldNam
 
         AutoGetCollectionForReadCommand renamedColl(_opCtx.get(), NamespaceString("test.x"));
         ASSERT_TRUE(renamedColl.getCollection());
-        ASSERT_EQUALS(renamedColl.getCollection()->uuid().get(), renamedCollectionUUID);
+        ASSERT_EQUALS(renamedColl.getCollection()->uuid(), renamedCollectionUUID);
 
         AutoGetCollectionForReadCommand createdColl(_opCtx.get(), NamespaceString("test.y"));
         ASSERT_FALSE(createdColl.getCollection());
@@ -1474,7 +1467,7 @@ TEST_F(RSRollbackTest, RollbackCollModCommandFailsIfRBIDChangesWhileSyncingColle
     auto collModOperation = std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
                                                      << "c"
                                                      << "ui"
-                                                     << coll->uuid().get()
+                                                     << coll->uuid()
                                                      << "ns"
                                                      << "test.t"
                                                      << "o"
@@ -1585,7 +1578,7 @@ TEST_F(RSRollbackTest, RollbackApplyOpsCommand) {
             _opCtx.get(), InsertStatement(BSON("_id" << 4)), nullOpDebug, false));
         wuow.commit();
     }
-    UUID uuid = coll->uuid().get();
+    UUID uuid = coll->uuid();
     const auto commonOperation = makeOpAndRecordId(1);
     const auto applyOpsOperation =
         std::make_pair(makeApplyOpsOplogEntry(Timestamp(Seconds(2), 0),
@@ -1743,7 +1736,7 @@ TEST_F(RSRollbackTest, RollbackCreateCollectionCommand) {
     auto createCollectionOperation = std::make_pair(BSON("ts" << Timestamp(Seconds(2), 0) << "op"
                                                               << "c"
                                                               << "ui"
-                                                              << coll->uuid().get()
+                                                              << coll->uuid()
                                                               << "ns"
                                                               << "test.t"
                                                               << "o"
@@ -1780,7 +1773,7 @@ TEST_F(RSRollbackTest, RollbackCollectionModificationCommand) {
                               << "validationLevel"
                               << "strict");
     auto collectionModificationOperation =
-        makeCommandOp(Timestamp(Seconds(2), 0), coll->uuid().get(), "test.t", collModCmd, 2);
+        makeCommandOp(Timestamp(Seconds(2), 0), coll->uuid(), "test.t", collModCmd, 2);
 
     class RollbackSourceLocal : public RollbackSourceMock {
     public:
@@ -1944,7 +1937,7 @@ TEST_F(RSRollbackTest, RollbackCollectionModificationCommandInvalidCollectionOpt
                               << "validationLevel"
                               << "strict");
     auto collectionModificationOperation =
-        makeCommandOp(Timestamp(Seconds(2), 0), coll->uuid().get(), "test.t", collModCmd, 2);
+        makeCommandOp(Timestamp(Seconds(2), 0), coll->uuid(), "test.t", collModCmd, 2);
 
 
     class RollbackSourceLocal : public RollbackSourceMock {
@@ -2418,7 +2411,7 @@ TEST_F(RSRollbackTest, RollbackFetchesTransactionOperationBeforeCommonPoint) {
     auto txnTable = _createCollection(_opCtx.get(), "config.transactions", options);
 
     auto commonOperation = makeOpAndRecordId(10);
-    UUID uuid = *coll->uuid();
+    UUID uuid = coll->uuid();
     auto lsid = makeLogicalSessionIdForTest();
     auto commitTxnEntry =
         BSON("ts" << Timestamp(Seconds(10), 12) << "t" << 10LL << "op"
@@ -2536,7 +2529,7 @@ TEST_F(RSRollbackTest, RollbackFetchesTransactionOperationBeforeCommonPoint) {
 
     } rollbackSource(std::unique_ptr<OplogInterface>(
                          new OplogInterfaceMock({commonOperation, operationBeforeCommonPoint})),
-                     *txnTable->uuid());
+                     txnTable->uuid());
 
     ASSERT_OK(syncRollback(_opCtx.get(),
                            OplogInterfaceMock({commitTxnOperation,
@@ -2562,7 +2555,7 @@ TEST_F(RSRollbackTest, RollbackIncompleteTransactionReturnsUnrecoverableRollback
     auto txnTable = _createCollection(_opCtx.get(), "config.transactions", options);
 
     auto commonOperation = makeOpAndRecordId(10);
-    UUID uuid = *coll->uuid();
+    UUID uuid = coll->uuid();
     auto lsid = makeLogicalSessionIdForTest();
     auto commitTxnEntry =
         BSON("ts" << Timestamp(Seconds(10), 12) << "t" << 10LL << "op"
@@ -2633,7 +2626,7 @@ TEST_F(RSRollbackTest, RollbackIncompleteTransactionReturnsUnrecoverableRollback
     private:
         UUID _txnTableUuid;
     } rollbackSource(std::unique_ptr<OplogInterface>(new OplogInterfaceMock({commonOperation})),
-                     *txnTable->uuid());
+                     txnTable->uuid());
 
 
     auto status = syncRollback(
diff --git a/src/mongo/db/repl/sync_tail_test.cpp b/src/mongo/db/repl/sync_tail_test.cpp
index 0c11fb1432b..90f18f7eb49 100644
--- a/src/mongo/db/repl/sync_tail_test.cpp
+++ b/src/mongo/db/repl/sync_tail_test.cpp
@@ -2767,7 +2767,7 @@ TEST_F(SyncTailTxnTableTest, RetryableWriteThenMultiStatementTxnWriteOnSameSessi
                                            << "ns"
                                            << nss().ns()
                                            << "ui"
-                                           << *uuid
+                                           << uuid
                                            << "o"
                                            << BSON("_id" << 2)))
                         << "partialTxn"
@@ -2826,7 +2826,7 @@ TEST_F(SyncTailTxnTableTest, MultiStatementTxnWriteThenRetryableWriteOnSameSessi
                                            << "ns"
                                            << nss().ns()
                                            << "ui"
-                                           << *uuid
+                                           << uuid
                                            << "o"
                                            << BSON("_id" << 2)))
                         << "partialTxn"
diff --git a/src/mongo/db/s/migration_destination_manager.cpp b/src/mongo/db/s/migration_destination_manager.cpp
index 01d36506bcf..481b0d2a707 100644
--- a/src/mongo/db/s/migration_destination_manager.cpp
+++ b/src/mongo/db/s/migration_destination_manager.cpp
@@ -605,7 +605,7 @@ void MigrationDestinationManager::cloneCollectionIndexesAndOptions(OperationCont
                         << "Cannot create collection "
                         << nss.ns()
                         << " because we already have an identically named collection with UUID "
-                        << (collection->uuid() ? collection->uuid()->toString() : "(none)")
+                        << collection->uuid()
                         << ", which differs from the donor's UUID "
                         << (donorUUID ? donorUUID->toString() : "(none)")
                         << ". Manually drop the collection on this shard if it contains data from "
@@ -674,7 +674,7 @@ void MigrationDestinationManager::cloneCollectionIndexesAndOptions(OperationCont
                 // before the index is added to the index catalog for correct rollback operation.
                 // See SERVER-35780 and SERVER-35070.
                 serviceContext->getOpObserver()->onCreateIndex(
-                    opCtx, collection->ns(), *(collection->uuid()), spec, true /* fromMigrate */);
+                    opCtx, collection->ns(), collection->uuid(), spec, true /* fromMigrate */);
 
                 // Since the collection is empty, we can add and commit the index catalog entry
                 // within a single WUOW.
diff --git a/src/mongo/db/s/migration_source_manager.cpp b/src/mongo/db/s/migration_source_manager.cpp
index ccd90364e31..e292320ba53 100644
--- a/src/mongo/db/s/migration_source_manager.cpp
+++ b/src/mongo/db/s/migration_source_manager.cpp
@@ -160,9 +160,7 @@ MigrationSourceManager::MigrationSourceManager(OperationContext* opCtx,
                 autoColl.getCollection());
 
         boost::optional<UUID> collectionUUID;
-        if (autoColl.getCollection()->uuid()) {
-            collectionUUID = autoColl.getCollection()->uuid().value();
-        }
+        collectionUUID = autoColl.getCollection()->uuid();
 
         auto optMetadata =
             CollectionShardingState::get(opCtx, getNss())->getCurrentMetadataIfKnown();
diff --git a/src/mongo/db/system_index.cpp b/src/mongo/db/system_index.cpp
index d6f6ebca0d2..a09cc9c64dc 100644
--- a/src/mongo/db/system_index.cpp
+++ b/src/mongo/db/system_index.cpp
@@ -182,7 +182,7 @@ Status verifySystemIndexes(OperationContext* opCtx) {
             if (indexes.empty()) {
                 try {
                     systemUsersFuture = generateSystemIndexForExistingCollection(
-                        opCtx, collection->uuid().get(), systemUsers, v3SystemUsersIndexSpec);
+                        opCtx, collection->uuid(), systemUsers, v3SystemUsersIndexSpec);
                 } catch (...) {
                     return exceptionToStatus();
                 }
@@ -200,7 +200,7 @@ Status verifySystemIndexes(OperationContext* opCtx) {
             if (indexes.empty()) {
                 try {
                     systemRolesFuture = generateSystemIndexForExistingCollection(
-                        opCtx, collection->uuid().get(), systemRoles, v3SystemRolesIndexSpec);
+                        opCtx, collection->uuid(), systemRoles, v3SystemRolesIndexSpec);
                 } catch (...) {
                     return exceptionToStatus();
                 }
@@ -252,7 +252,7 @@ void createSystemIndexes(OperationContext* opCtx, Collection* collection) {
     }
     if (!indexSpec.isEmpty()) {
         opCtx->getServiceContext()->getOpObserver()->onCreateIndex(
-            opCtx, ns, *(collection->uuid()), indexSpec, false /* fromMigrate */);
+            opCtx, ns, collection->uuid(), indexSpec, false /* fromMigrate */);
         // Note that the opObserver is called prior to creating the index.  This ensures the index
         // write gets the same storage timestamp as the oplog entry.
         fassert(40456,
diff --git a/src/mongo/dbtests/storage_timestamp_tests.cpp b/src/mongo/dbtests/storage_timestamp_tests.cpp
index 76e74a1d6e0..4a0d996cd55 100644
--- a/src/mongo/dbtests/storage_timestamp_tests.cpp
+++ b/src/mongo/dbtests/storage_timestamp_tests.cpp
@@ -279,7 +279,7 @@ public:
                                coll,
                                [&](const BSONObj& indexSpec) {
                                    _opCtx->getServiceContext()->getOpObserver()->onCreateIndex(
-                                       _opCtx, coll->ns(), *(coll->uuid()), indexSpec, false);
+                                       _opCtx, coll->ns(), coll->uuid(), indexSpec, false);
                                },
                                MultiIndexBlock::kNoopOnCommitFn));
             // The timestamping repsponsibility is placed on the caller rather than the
@@ -713,7 +713,7 @@ public:
                                    << "ns"
                                    << nss.ns()
                                    << "ui"
-                                   << autoColl.getCollection()->uuid().get()
+                                   << autoColl.getCollection()->uuid()
                                    << "o"
                                    << BSON("_id" << idx))
                          << BSON("ts" << firstInsertTime.addTicks(idx).asTimestamp() << "t" << 1LL
@@ -778,7 +778,7 @@ public:
 
         oplogEntryBuilder << "v" << 2 << "op"
                           << "i"
-                          << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid().get();
+                          << "ns" << nss.ns() << "ui" << autoColl.getCollection()->uuid();
 
         auto oplogEntry = oplogEntryBuilder.done();
         ASSERT_OK(repl::SyncTail::syncApply(
@@ -834,7 +834,7 @@ public:
                                << "ns"
                                << nss.ns()
                                << "ui"
-                               << autoColl.getCollection()->uuid().get()
+                               << autoColl.getCollection()->uuid()
                                << "o"
                                << BSON("_id" << num))})
                     .getStatus());
@@ -899,7 +899,7 @@ public:
                                << "ns"
                                << nss.ns()
                                << "ui"
-                               << autoColl.getCollection()->uuid().get()
+                               << autoColl.getCollection()->uuid()
                                << "o2"
                                << BSON("_id" << 0)
                                << "o"
@@ -944,7 +944,7 @@ public:
                        << "ns"
                        << nss.ns()
                        << "ui"
-                       << autoColl.getCollection()->uuid().get()
+                       << autoColl.getCollection()->uuid()
                        << "o"
                        << BSON("_id" << 0 << "field" << 0)),
              BSON("ts" << insertTime.addTicks(1).asTimestamp() << "t" << 1LL << "op"
@@ -952,7 +952,7 @@ public:
                        << "ns"
                        << nss.ns()
                        << "ui"
-                       << autoColl.getCollection()->uuid().get()
+                       << autoColl.getCollection()->uuid()
                        << "o"
                        << BSON("_id" << 0))}));
 
@@ -998,7 +998,7 @@ public:
                                                << "ns"
                                                << nss.ns()
                                                << "ui"
-                                               << autoColl.getCollection()->uuid().get()
+                                               << autoColl.getCollection()->uuid()
                                                << "o"
                                                << BSON("_id" << 0)),
                                           BSON("op"
@@ -1006,7 +1006,7 @@ public:
                                                << "ns"
                                                << nss.ns()
                                                << "ui"
-                                               << autoColl.getCollection()->uuid().get()
+                                               << autoColl.getCollection()->uuid()
                                                << "o"
                                                << BSON("_id" << 1))});
         ASSERT_OK(swResult);
@@ -1057,7 +1057,7 @@ public:
                                                << "ns"
                                                << nss.ns()
                                                << "ui"
-                                               << autoColl.getCollection()->uuid().get()
+                                               << autoColl.getCollection()->uuid()
                                                << "o"
                                                << BSON("_id" << 0 << "field" << 0)),
                                           BSON("op"
@@ -1065,7 +1065,7 @@ public:
                                                << "ns"
                                                << nss.ns()
                                                << "ui"
-                                               << autoColl.getCollection()->uuid().get()
+                                               << autoColl.getCollection()->uuid()
                                                << "o"
                                                << BSON("_id" << 0))});
         ASSERT_OK(swResult);
@@ -1212,34 +1212,33 @@ public:
             { ASSERT_FALSE(AutoGetCollectionForReadCommand(_opCtx, nss2).getCollection()); }
 
             BSONObjBuilder resultBuilder;
-            auto swResult =
-                doNonAtomicApplyOps(dbName,
-                                    {
-                                        BSON("ts" << presentTs << "t" << 1LL << "op"
-                                                  << "i"
-                                                  << "ns"
-                                                  << nss1.ns()
-                                                  << "ui"
-                                                  << autoColl.getCollection()->uuid().get()
-                                                  << "o"
-                                                  << doc1),
-                                        BSON("ts" << futureTs << "t" << 1LL << "op"
-                                                  << "c"
-                                                  << "ui"
-                                                  << uuid2
-                                                  << "ns"
-                                                  << nss2.getCommandNS().ns()
-                                                  << "o"
-                                                  << BSON("create" << nss2.coll())),
-                                        BSON("ts" << insert2Ts << "t" << 1LL << "op"
-                                                  << "i"
-                                                  << "ns"
-                                                  << nss2.ns()
-                                                  << "ui"
-                                                  << uuid2
-                                                  << "o"
-                                                  << doc2),
-                                    });
+            auto swResult = doNonAtomicApplyOps(dbName,
+                                                {
+                                                    BSON("ts" << presentTs << "t" << 1LL << "op"
+                                                              << "i"
+                                                              << "ns"
+                                                              << nss1.ns()
+                                                              << "ui"
+                                                              << autoColl.getCollection()->uuid()
+                                                              << "o"
+                                                              << doc1),
+                                                    BSON("ts" << futureTs << "t" << 1LL << "op"
+                                                              << "c"
+                                                              << "ui"
+                                                              << uuid2
+                                                              << "ns"
+                                                              << nss2.getCommandNS().ns()
+                                                              << "o"
+                                                              << BSON("create" << nss2.coll())),
+                                                    BSON("ts" << insert2Ts << "t" << 1LL << "op"
+                                                              << "i"
+                                                              << "ns"
+                                                              << nss2.ns()
+                                                              << "ui"
+                                                              << uuid2
+                                                              << "o"
+                                                              << doc2),
+                                                });
             ASSERT_OK(swResult);
         }
 
@@ -1329,7 +1328,7 @@ public:
         UUID uuid = UUID::gen();
         {
             AutoGetCollection autoColl(_opCtx, nss, LockMode::MODE_IX);
-            uuid = autoColl.getCollection()->uuid().get();
+            uuid = autoColl.getCollection()->uuid();
         }
         auto indexName = "a_1";
         auto indexSpec =
@@ -1414,7 +1413,7 @@ public:
         UUID uuid = UUID::gen();
         {
             AutoGetCollection autoColl(_opCtx, nss, LockMode::MODE_IX);
-            uuid = autoColl.getCollection()->uuid().get();
+            uuid = autoColl.getCollection()->uuid();
         }
         auto indexName = "a_1";
         auto indexSpec =
@@ -2019,7 +2018,7 @@ public:
                     if (SimulatePrimary) {
                         // The timestamping responsibility for each index is placed on the caller.
                         _opCtx->getServiceContext()->getOpObserver()->onCreateIndex(
-                            _opCtx, nss, *(autoColl.getCollection()->uuid()), indexSpec, false);
+                            _opCtx, nss, autoColl.getCollection()->uuid(), indexSpec, false);
                     } else {
                         ASSERT_OK(_opCtx->recoveryUnit()->setTimestamp(
                             _clock->getClusterTime().asTimestamp()));
@@ -2200,7 +2199,7 @@ public:
                     if (SimulatePrimary) {
                         // The timestamping responsibility for each index is placed on the caller.
                         _opCtx->getServiceContext()->getOpObserver()->onCreateIndex(
-                            _opCtx, nss, *(autoColl.getCollection()->uuid()), indexSpec, false);
+                            _opCtx, nss, autoColl.getCollection()->uuid(), indexSpec, false);
                     } else {
                         ASSERT_OK(_opCtx->recoveryUnit()->setTimestamp(
                             _clock->getClusterTime().asTimestamp()));
@@ -2495,7 +2494,7 @@ public:
         UUID uuid = UUID::gen();
         {
             AutoGetCollectionForRead autoColl(_opCtx, ns);
-            uuid = autoColl.getCollection()->uuid().get();
+            uuid = autoColl.getCollection()->uuid();
             ASSERT_EQ(itCount(autoColl.getCollection()), 0);
         }
 
@@ -2609,7 +2608,7 @@ public:
             // Create the collection and insert a document.
             reset(nss);
             AutoGetCollection autoColl(_opCtx, nss, LockMode::MODE_IX);
-            collUUID = *(autoColl.getCollection()->uuid());
+            collUUID = autoColl.getCollection()->uuid();
             WriteUnitOfWork wuow(_opCtx);
             insertDocument(autoColl.getCollection(),
                            InsertStatement(doc, setupStart.asTimestamp(), presentTerm));
@@ -2807,7 +2806,7 @@ public:
             AutoGetCollection autoColl(_opCtx, nss, LockMode::MODE_IX);
             auto coll = autoColl.getCollection();
             ASSERT(coll);
-            ui = coll->uuid().get();
+            ui = coll->uuid();
         }
 
         presentTs = _clock->getClusterTime().asTimestamp();
@@ -2977,18 +2976,17 @@ public:
             assertFilteredDocumentAtTimestamp(coll, query2, nullTs, doc2);
 
             // Implicit commit oplog entry should exist at commitEntryTs.
-            const auto commitFilter =
-                BSON("ts" << commitEntryTs << "o"
-                          << BSON("applyOps" << BSON_ARRAY(BSON("op"
-                                                                << "i"
-                                                                << "ns"
-                                                                << nss.ns()
-                                                                << "ui"
-                                                                << coll->uuid().get()
-                                                                << "o"
-                                                                << doc2))
-                                             << "count"
-                                             << 2));
+            const auto commitFilter = BSON(
+                "ts" << commitEntryTs << "o" << BSON("applyOps" << BSON_ARRAY(BSON("op"
+                                                                                   << "i"
+                                                                                   << "ns"
+                                                                                   << nss.ns()
+                                                                                   << "ui"
+                                                                                   << coll->uuid()
+                                                                                   << "o"
+                                                                                   << doc2))
+                                                                << "count"
+                                                                << 2));
             assertOplogDocumentExistsAtTimestamp(commitFilter, presentTs, false);
             assertOplogDocumentExistsAtTimestamp(commitFilter, beforeTxnTs, false);
             assertOplogDocumentExistsAtTimestamp(commitFilter, firstOplogEntryTs, false);
@@ -3011,7 +3009,7 @@ public:
                                                                 << "ns"
                                                                 << nss.ns()
                                                                 << "ui"
-                                                                << coll->uuid().get()
+                                                                << coll->uuid()
                                                                 << "o"
                                                                 << doc))
                                              << "partialTxn"
@@ -3190,7 +3188,7 @@ public:
                                                                 << "ns"
                                                                 << nss.ns()
                                                                 << "ui"
-                                                                << coll->uuid().get()
+                                                                << coll->uuid()
                                                                 << "o"
                                                                 << doc))
                                              << "partialTxn"
@@ -3202,20 +3200,19 @@ public:
             assertOplogDocumentExistsAtTimestamp(firstOplogEntryFilter, commitEntryTs, true);
             assertOplogDocumentExistsAtTimestamp(firstOplogEntryFilter, nullTs, true);
             // The prepare oplog entry should exist at prepareEntryTs and onwards.
-            const auto prepareOplogEntryFilter =
-                BSON("ts" << prepareEntryTs << "o"
-                          << BSON("applyOps" << BSON_ARRAY(BSON("op"
-                                                                << "i"
-                                                                << "ns"
-                                                                << nss.ns()
-                                                                << "ui"
-                                                                << coll->uuid().get()
-                                                                << "o"
-                                                                << doc2))
-                                             << "prepare"
-                                             << true
-                                             << "count"
-                                             << 2));
+            const auto prepareOplogEntryFilter = BSON(
+                "ts" << prepareEntryTs << "o" << BSON("applyOps" << BSON_ARRAY(BSON("op"
+                                                                                    << "i"
+                                                                                    << "ns"
+                                                                                    << nss.ns()
+                                                                                    << "ui"
+                                                                                    << coll->uuid()
+                                                                                    << "o"
+                                                                                    << doc2))
+                                                                 << "prepare"
+                                                                 << true
+                                                                 << "count"
+                                                                 << 2));
             assertOplogDocumentExistsAtTimestamp(prepareOplogEntryFilter, presentTs, false);
             assertOplogDocumentExistsAtTimestamp(prepareOplogEntryFilter, beforeTxnTs, false);
             assertOplogDocumentExistsAtTimestamp(prepareOplogEntryFilter, firstOplogEntryTs, false);
@@ -3324,7 +3321,7 @@ public:
                 AutoGetCollection autoColl(_opCtx, nss, LockMode::MODE_IX);
                 auto coll = autoColl.getCollection();
                 ASSERT(coll);
-                ui = coll->uuid().get();
+                ui = coll->uuid();
             }
 
             // The prepare oplog entry should exist at firstOplogEntryTs and onwards.