SERVER-61158 add CreateIndexEntryFlags::kUpdateMetadata

This also restores KVEngine::alterIdentMetadata() which was removed
during 4.4 FCV-related work in commit 8e4f280e492fe2bfb7842733ff640030d559cd0a.

5 files changed, 38 insertions, 1 deletions

diff --git a/src/mongo/db/catalog/index_catalog.h b/src/mongo/db/catalog/index_catalog.h
index 624f0fe427c..1dfcc641869 100644
--- a/src/mongo/db/catalog/index_catalog.h
+++ b/src/mongo/db/catalog/index_catalog.h
@@ -92,7 +92,13 @@ enum class CreateIndexEntryFlags : int {
      * built. This is used when starting a node in standalone mode and a two-phase index build
      * is incomplete. kIsReady must not also be set.
      */
-    kFrozen = 0x4
+    kFrozen = 0x4,
+    /**
+     * kUpdateMetadata indicates that the index metadata in the storage engine should be updated
+     * based on changes to the IndexDescriptor.
+     * This is used when making an index unique through the collMod command.
+     */
+    kUpdateMetadata = 0x8
 };
 
 inline bool operator&(CreateIndexEntryFlags lhs, CreateIndexEntryFlags rhs) {
diff --git a/src/mongo/db/catalog/index_catalog_impl.cpp b/src/mongo/db/catalog/index_catalog_impl.cpp
index 5e0c8b0f593..261f0f8fb71 100644
--- a/src/mongo/db/catalog/index_catalog_impl.cpp
+++ b/src/mongo/db/catalog/index_catalog_impl.cpp
@@ -431,6 +431,15 @@ IndexCatalogEntry* IndexCatalogImpl::createIndexEntry(OperationContext* opCtx,
         opCtx, collection, ident, std::move(descriptor), frozen);
 
     IndexDescriptor* desc = entry->descriptor();
+
+    // In some cases, it may be necessary to update the index metadata in the storage engine in
+    // order to obtain the correct SortedDataInterface. One such scenario is found in converting an
+    // index to be unique.
+    bool isUpdateMetadata = CreateIndexEntryFlags::kUpdateMetadata & flags;
+    if (isUpdateMetadata) {
+        engine->getEngine()->alterIdentMetadata(opCtx, ident, desc);
+    }
+
     const auto& collOptions = collection->getCollectionOptions();
     std::unique_ptr<SortedDataInterface> sdi =
         engine->getEngine()->getSortedDataInterface(opCtx, collOptions, ident, desc);
diff --git a/src/mongo/db/storage/kv/kv_engine.h b/src/mongo/db/storage/kv/kv_engine.h
index 2503db506b8..b4f14fffcdf 100644
--- a/src/mongo/db/storage/kv/kv_engine.h
+++ b/src/mongo/db/storage/kv/kv_engine.h
@@ -175,6 +175,10 @@ public:
         return status;
     }
 
+    virtual void alterIdentMetadata(OperationContext* opCtx,
+                                    StringData ident,
+                                    const IndexDescriptor* desc) {}
+
     /**
      * See StorageEngine::flushAllFiles for details
      */
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
index 45fd173275e..991b8c3afbc 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
@@ -1646,6 +1646,20 @@ std::unique_ptr<RecordStore> WiredTigerKVEngine::makeTemporaryRecordStore(Operat
     return std::move(rs);
 }
 
+void WiredTigerKVEngine::alterIdentMetadata(OperationContext* opCtx,
+                                            StringData ident,
+                                            const IndexDescriptor* desc) {
+    WiredTigerSession session(_conn);
+    std::string uri = _uri(ident);
+
+    // Make the alter call to update metadata without taking exclusive lock to avoid conflicts with
+    // concurrent operations.
+    std::string alterString =
+        WiredTigerIndex::generateAppMetadataString(*desc) + "exclusive_refreshed=false,";
+    invariantWTOK(
+        session.getSession()->alter(session.getSession(), uri.c_str(), alterString.c_str()));
+}
+
 Status WiredTigerKVEngine::dropIdent(RecoveryUnit* ru,
                                      StringData ident,
                                      StorageEngine::DropIdentCallback&& onDrop) {
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h
index 1301a0c07b8..b45c0269b6c 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h
@@ -170,6 +170,10 @@ public:
 
     void dropIdentForImport(OperationContext* opCtx, StringData ident) override;
 
+    void alterIdentMetadata(OperationContext* opCtx,
+                            StringData ident,
+                            const IndexDescriptor* desc) override;
+
     Status okToRename(OperationContext* opCtx,
                       StringData fromNS,
                       StringData toNS,