Migrating data stored in a MongoDB collection from MongoDBChatMessageHistory to MongoDBSaver checkpointer

[ZerlionAlistor]

Hello,

I'm increasingly interested in transitioning from LangChain to LangGraph, and I've been reviewing the documentation for the latter.

Overall, I understand that the purpose of the checkpointer is to save the states at each step of the graph.
I've also understood that it's still possible to use RunnableWithMessageHistory within the nodes of LangGraph graphs to handle memory.

However, I doubt that this is the most efficient way to properly leverage LangGraph, especially when it comes to using graph checkpoints (such as for human-in-the-loop use cases).

So my question is the following:
Is there a way to migrate data from an existing MongoDB collection that handles conversation history with MongoDBChatMessageHistory class to another collection with the format required for use with the checkpointers?
I couldn’t find anything in the documentation that describes how to migrate existing data.

And a second question: I noticed that the checkpoints are stored in two different collections (checkpoint_writes and checkpoints). What is the difference between the two?

Thanks in advance!