I am creating an application which will store a (semi) real-time feed of a few different scales around a certain location. The weights of each scale will be put in a table with only as many rows as scales. The scale app feeds the MySQL database a new weight every second, which a PHP web app reads every 3 seconds. It doesn't seem like very much traffic that would page the hard drive very much, or if the difference would be negligible, but I'm wondering if it would be more efficient or make more sense to use a Memory/HEAP table vs a normal MyISAM table.
Well, if you're expecting a large amount of data, I think you almost have to go MyISAM. You'll likely run out of memory if you store it all in a memory table. Not to mention that you'll lose all of your data upon power loss with a HEAP engine (Keep in mind, you may want that depending on your use case)...