If a database is in memory does it still need indexing? INFO I'm following lessons on databases. We're learning about indices now.

Question

If big parts of a table are in the memory, would using a index still have benefits?

My side

I would assume indexing makes a search always faster, so yes it would have benefits. I hope this is not to much opinion based and maybe someone have a good explained reason why or why not it has benefits.
Yes, an index will help.  Without an index all the RDBMS can do is start at the beginning of the data and work its way toward the end, stopping when it finds what it's looking for.  This is a O(N) operation.  With a B-Tree index in place it reduces to O(log(N)).  This is true whether the data is held on disk or in memory.