I have a database that won't grow much in size. It's current size is about 1 GB.
Achieving the fastest performance is desired.
Question: When should I use Memcache vs simply using MySQL Innodb ability to store all my content within RAM (innodb_buffer_pool_size)?
I would only resort to memcached if you require more than one server to hold everything in RAM. Otherwise, you're adding complexity for not much functionality.
mysql is more performance degradated on much threads then memcached. so when you will get much simultaneous requests - memcached will respond almost in the same constant time, but mysql's time will be worse.
anyway - until you get about 3-5k tps (or more) to write - there is no any reasons to make project infrastructure more complex.
来源：https://stackoverflow.com/questions/2444011/memcache-vs-mysql-in-memory