eRIZ

I know it would sound weird but make a separated select FOR EACH record. Why? JOINs are pain in the ass when you consider aggresive caching.

JOIN make a deadlock and wastes too much of space of eg. Memcached. (common part of data of every record).

Moreover, using join you can't scale at many machines scope. Using JOIN all joined tables MUST BE accessible for one RDBMS. Using SELECT approach you can scale it into different machines without replication on even different services. For example, user database is stored on MySQL but post data inside Redis. It will be fast as hell.

Yes, it sounds weird but any app scaled quite larger than one machine drops the normalization and goes into the scalability.

Two years ago I was amazed too when the CTO of the company consisting of hundreds of memcached-only machines told me so. But it HAS a point.

You should filter the requests because it enforces PHP to parse all requests.

For example, someone uploads JPEG file with PHP code in EXIF. Then runs from URL and server is being exploited...