I want to add autocomplete feature to my retail product app - similar to google/youtube search's autocomplete.

My backend stack is spring boot.

There are a million different products in the database.

Below are my thoughts:

1. create an array and fetch the names while loading the screen -> ( seems overkill for a million records)
2. wait for 2 or 3 characters and do a backend search with filter -> wont be fast enough.

How does google/youtube achieve this ? the results are instantaneous without any backend calls