在具有许多行的表上进行MySQL速度优化：处理它的最佳方法是什么？

I'm developping a chat application. I want to keep everything logged into a table (i.e. "who said what and when"). I hope that in a near future I'll have thousands of rows. I was wondering : what is the best way to optimize the table, knowing that I'll do often rows insertion and sometimes group reading (i.e. showing an entire conversation from a user (look when he/she logged in/started to chat then look when he/she quit then show the entire conversation)).I'm developping a chat application. I want to k