How to get all results , By Ignoring "size" in query

By Default a query return 10 results, But i can handle all results and need them all at a time .Yes i can specify size to get all. But for i don't know how many results are their. So , may i make two queries first to get size and second with Query having exact "size". ,Right now i am using "max size limit" as my "size "in query, But i think this might be making elasticsearch use more RAM. Please guide me, on this topic

Look at the scroll API.