Revert "SERVER-30005: remove $isolated/$atomic option"

This reverts commit cd950b113ee0d00e88036b2fe6306866c7ba27f9.

1 files changed, 5 insertions, 2 deletions

diff --git a/src/mongo/db/catalog/index_catalog_impl.cpp b/src/mongo/db/catalog/index_catalog_impl.cpp
index 525ace9c0e5..bb19de5ab76 100644
--- a/src/mongo/db/catalog/index_catalog_impl.cpp
+++ b/src/mongo/db/catalog/index_catalog_impl.cpp
@@ -686,12 +686,15 @@ Status IndexCatalogImpl::_isSpecOk(OperationContext* opCtx, const BSONObj& spec)
             new ExpressionContext(opCtx, collator.get()));
 
         // Parsing the partial filter expression is not expected to fail here since the
-        // expression would have been successfully parsed upstream during index creation.
+        // expression would have been successfully parsed upstream during index creation. However,
+        // filters that were allowed in partial filter expressions prior to 3.6 may be present in
+        // the index catalog and must also successfully parse (e.g., partial index filters with the
+        // $isolated/$atomic option).
         StatusWithMatchExpression statusWithMatcher =
             MatchExpressionParser::parse(filterElement.Obj(),
                                          std::move(expCtx),
                                          ExtensionsCallbackNoop(),
-                                         MatchExpressionParser::kBanAllSpecialFeatures);
+                                         MatchExpressionParser::kIsolated);
         if (!statusWithMatcher.isOK()) {
             return statusWithMatcher.getStatus();
         }