Revert "SERVER-63089 Disallow downgrade when the index comment field exists"

This reverts commit 806bb2afb2415a2ecc9cc8306e1bfb606a1f74ec.

2 files changed, 0 insertions, 32 deletions

diff --git a/src/mongo/db/commands/set_feature_compatibility_version_command.cpp b/src/mongo/db/commands/set_feature_compatibility_version_command.cpp
index 4de98443c06..b61878d5233 100644
--- a/src/mongo/db/commands/set_feature_compatibility_version_command.cpp
+++ b/src/mongo/db/commands/set_feature_compatibility_version_command.cpp
@@ -718,33 +718,6 @@ private:
                     });
             }
 
-            // TODO SERVER-63171: Only check on last-lts when FCV 5.3 becomes last-continuous.
-            // TODO SERVER-63172: Remove once FCV 6.0 becomes last-lts.
-            for (const auto& tenantDbName : DatabaseHolder::get(opCtx)->getNames()) {
-                Lock::DBLock dbLock(opCtx, tenantDbName.dbName(), MODE_IX);
-                catalog::forEachCollectionFromDb(
-                    opCtx, tenantDbName.dbName(), MODE_X, [&](const CollectionPtr& collection) {
-                        auto indexCatalog = collection->getIndexCatalog();
-                        auto indexIt = indexCatalog->getIndexIterator(
-                            opCtx, true /* includeUnfinishedIndexes */);
-                        while (indexIt->more()) {
-                            auto indexEntry = indexIt->next();
-                            uassert(
-                                ErrorCodes::CannotDowngrade,
-                                fmt::format(
-                                    "Cannot downgrade the cluster when there are indexes that have "
-                                    "the 'comment' field. Use listIndexes to find them and drop "
-                                    "the indexes or use collMod to manually remove the field "
-                                    "before downgrading. First detected incompatible index name: "
-                                    "'{}' on collection: '{}'",
-                                    indexEntry->descriptor()->indexName(),
-                                    collection->ns().toString()),
-                                indexEntry->descriptor()->comment().isEmpty());
-                        }
-                        return true;
-                    });
-            }
-
             // Drop the pre-images collection if 'changeStreamPreAndPostImages' feature flag is not
             // enabled on the downgrade version.
             // TODO SERVER-61770: Remove once FCV 6.0 becomes last-lts.
diff --git a/src/mongo/db/index/index_descriptor.cpp b/src/mongo/db/index/index_descriptor.cpp
index fd762758bcc..07ae8f1cdc5 100644
--- a/src/mongo/db/index/index_descriptor.cpp
+++ b/src/mongo/db/index/index_descriptor.cpp
@@ -41,7 +41,6 @@
 #include "mongo/db/matcher/expression_parser.h"
 #include "mongo/db/query/collation/collator_factory_interface.h"
 #include "mongo/db/server_options.h"
-#include "mongo/db/storage/storage_parameters_gen.h"
 
 namespace mongo {
 
@@ -137,10 +136,6 @@ IndexDescriptor::IndexDescriptor(const std::string& accessMethodName, BSONObj in
     }
 
     if (BSONElement commentElement = _infoObj[kCommentFieldName]) {
-        uassert(
-            ErrorCodes::InvalidOptions,
-            "createIndex does not support the 'comment' field",
-            feature_flags::gCollModIndexUnique.isEnabled(serverGlobalParams.featureCompatibility));
         invariant(commentElement.isABSONObj());
         _comment = commentElement.Obj().getOwned();
     }