The parameter that controls how much memory is used to store indexes for InnoDB is
key_buffer_size
innodb_buffer_pool_size
innodb_key_buffer_size
read_buffer_size
The parameter that controls how much memory is used to cache table data for InnoDB is
The parameter that controls how much memory is used to cache table data for MyISAM is
table_cache
The parameter that controls how much memory is used to cache index data for MyISAM is
The read_buffer_size parameter should not be made too large because
if many threads are performing full scans , you will have a problem
it is always possible to add more indexes so that MySQL will never need to do a full table scan
it wastes disk space
none of the above