SERVER-37313 Secondary foreground index build should take Database X rather than Global X lock

2 files changed, 8 insertions, 1 deletions

diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index bd41e12bd1e..e2c497de5f7 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -232,6 +232,11 @@ void createIndexForApplyOps(OperationContext* opCtx,
                             const NamespaceString& indexNss,
                             IncrementOpsAppliedStatsFn incrementOpsAppliedStats,
                             OplogApplication::Mode mode) {
+    // Lock the database if it's not locked.
+    boost::optional<Lock::DBLock> dbLock;
+    if (!opCtx->lockState()->isLocked()) {
+        dbLock.emplace(opCtx, indexNss.db(), MODE_X);
+    }
     // Check if collection exists.
     Database* db = DatabaseHolder::getDatabaseHolder().get(opCtx, indexNss.ns());
     auto indexCollection = db ? db->getCollection(opCtx, indexNss) : nullptr;
diff --git a/src/mongo/db/repl/sync_tail.cpp b/src/mongo/db/repl/sync_tail.cpp
index e3473ed5626..f5e11dda175 100644
--- a/src/mongo/db/repl/sync_tail.cpp
+++ b/src/mongo/db/repl/sync_tail.cpp
@@ -312,7 +312,9 @@ Status SyncTail::syncApply(OperationContext* opCtx,
             // The command entry has been parsed before, so it must be valid.
             auto entry = uassertStatusOK(OplogEntry::parse(op));
             const StringData commandName(op["o"].embeddedObject().firstElementFieldName());
-            if (!op.getBoolField("prepare") && commandName != "abortTransaction") {
+            // SERVER-37313: createIndex does not need to take the Global X lock.
+            if (!op.getBoolField("prepare") && commandName != "abortTransaction" &&
+                commandName != "createIndexes") {
                 globalWriteLock.emplace(opCtx);
             }