Search Index for document repo-System Design

Was asked following question in System Design round:
You are given a document repo. It has millions of documents. You have to create a search service with document repo as source of information. Documents can be added and removed. How will you design such a system.

I created a design with
Client -> LB -> Service -> Elastic Search Index

DocRepo -> MessageQueue -> Ingestor -> Elastic search service

Seemed like a very basic design, but interviewer was looking for more. Not sure how i should have attacked the problem. Any hints?

Comments (2)