SERVER-40258 Relax locking requirements for sharding metadata refresh on shards

1 files changed, 3 insertions, 2 deletions

diff --git a/src/mongo/db/db_raii.cpp b/src/mongo/db/db_raii.cpp
index fae5952f834..8cf2455629b 100644
--- a/src/mongo/db/db_raii.cpp
+++ b/src/mongo/db/db_raii.cpp
@@ -318,8 +318,9 @@ AutoGetCollectionForReadCommand::AutoGetCollectionForReadCommand(
                                              : kDoNotChangeProfilingLevel,
                     deadline) {
     if (!_autoCollForRead.getView()) {
-        // We have both the DB and collection locked, which is the prerequisite to do a stable shard
-        // version check, but we'd like to do the check after we have a satisfactory snapshot.
+        // Perform the check early so the query planner would be able to extract the correct
+        // shard key. Also make sure that version is compatible if query planner decides to
+        // use an empty plan.
         auto css = CollectionShardingState::get(opCtx, _autoCollForRead.getNss());
         css->checkShardVersionOrThrow(opCtx);
     }