Are MySQL indexes larger than RAM?

Question

MySQL

Now the server has 1024 MB of RAM, the size of the indexes in the table is 900 MB, and it will exceed a little more.
Question: where to read what will happen if it is exceeded. For example: will performance drop evenly on all requests, or will it drop on some, but some will be fine? Are the indexes stored in RAM in their entirety or only some of their parts, for example, the index cache?

Answer 1

www.mysql.ru/docs/man/Memory_use.html
indexes are comparable to the size of the database, and the size of the database - with the size of the screws
, no memory is enough