From c112d7334d6cac3296b877250d3f575fbfd46da2 Mon Sep 17 00:00:00 2001
From: Lucas Rodrigues <104941391+ldesousa-stf@users.noreply.github.com>
Date: Sun, 4 Jun 2023 17:39:56 -0400
Subject: [PATCH] Update MongoDBChatMessageHistory to create an index on
 SessionId (#5632)

All the queries to the database are done based on the SessionId
property, this will optimize how Mongo retrieves all messages from a
session

#### Who can review?

Tag maintainers/contributors who might be interested:
@dev2049
---
 langchain/memory/chat_message_histories/mongodb.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/langchain/memory/chat_message_histories/mongodb.py b/langchain/memory/chat_message_histories/mongodb.py
index 3455d812..a6965af3 100644
--- a/langchain/memory/chat_message_histories/mongodb.py
+++ b/langchain/memory/chat_message_histories/mongodb.py
@@ -47,6 +47,7 @@ class MongoDBChatMessageHistory(BaseChatMessageHistory):
 
         self.db = self.client[database_name]
         self.collection = self.db[collection_name]
+        self.collection.create_index("SessionId")
 
     @property
     def messages(self) -> List[BaseMessage]:  # type: ignore