Session type goes directly with the kind of project you handle. Majority of commercial apps need ACL, so you already have your SQL access. I say let Mysql do whatever it's good to do. The Query optimisation could change by project, because at some point you can remove some security layer to prevent that, but at which price ?
For most standard real world application, one sql is nothing, if your system get up to MANY and i say MANY connection, you prolly want to think about what is the best for scability, filesystem isnt always the best realy, so database will be a better choice again.
So, what range of security do you need ? this is the question, when i build basic website with small backend, i don't care much, when i build major client application i'll go with the SQL biiiiig time.
Good luck.
popcorned ; good to see you active and take time for your libs, good work !
