Content-type (and metadata) in mogilefs

[dormando]

> It could also serve as a base for similar needs, such as simple security
> checks or whatnot - think app/mogile-level cookie...
> 
> Does this make sense ? Or is there a very good reason why it'd be evil
> to put any of that stuff in mogile ?
> 
> Stefan

(IMHO land here)

Every time I go down this road I realize a few things:

1) Should just be using memcached in the app.
2) Use perlbal header caching.
3) It's the same DB access, different place.

So whether you store the headers in your application's DB or in mogile's 
DB, you'll need to access it "from the database" either way. If you push 
that into mogilefs you potentially lose the flexibility of having your 
developers be able to fiddle with how file headers are returned.

Your *goal* should be to not talk to the trackers for every file access 
anyway. Cache the headers + paths in memcached under a common key. Then 
80-90% of your accesses won't bother your application, and you retain 
the ability to fetch file data from however your storage looks like at 
the moment.

-Dormando