Mondodb connection improvement

libs/community/langchain_community/chat_message_histories/mongodb.py

@@ -24,6 +24,7 @@ class MongoDBChatMessageHistory(BaseChatMessageHistory):
             of a single chat session.
         database_name: name of the database to use
         collection_name: name of the collection to use
+        index_creation: bool for collection index-creation. By default index_creation is True
     """
 
     def __init__(
@@ -32,6 +33,7 @@ def __init__(
         session_id: str,
         database_name: str = DEFAULT_DBNAME,
         collection_name: str = DEFAULT_COLLECTION_NAME,
+        index_creation:bool =True
     ):
         from pymongo import MongoClient, errors
 
@@ -47,7 +49,11 @@ def __init__(
 
         self.db = self.client[database_name]
         self.collection = self.db[collection_name]
-        self.collection.create_index("SessionId")
+        if index_creation: 
+            """
+            Conditional Index Creation for collection
+            """
+            self.collection.create_index("SessionId")
 
     @property
     def messages(self) -> List[BaseMessage]:  # type: ignore