Retriever

The retriever is setup automatically when you do index.as_query_engine()

Or are you asking how to use a langchain retriever in llama index? That's not easily possible

yeah i want to use llama index to store the index and use langchain to read the index and then build a chatbot with memory history, so i cant use index.as_query_engine()( i think it's doenst remeber the previous conversation?), that 's not easily possible?

Yea that's not easily possible I think, it would take some hacking to get it to work lol

Usually you would make llama index a tool in a langchain agent

at least that's the easiest approach I think

If you need memory though, you could also use a llama index agent

thanks