Critique my MySQL Database Design for Unlimited DYNAMIC Fields

Question

Looking for a scalable, flexible and fast database design for \'Build your own form\' style website - e.g Wufoo.

Rules:

1. User has only 1 Form they can build

Answer 1

At OSCON yesterday, Josh Berkus gave a good tutorial on DB design, and he spent a good fraction of it mercilessly tearing into such "EAV"il tables; you should be able to find his slides on the OSCON site soon, and eventually the audio recording of his whole tutorial online (the latter will probably take a while).

You'll need a join per attribute (multiple instances of the values table, one per attribute you're fetching or updating) so I don't know what you mean by "less join tables". Joining many instances of the same table isn't a particularly fast operation, and your design makes indices nearly unfeasible and unusable.

At least as a minor improvement use per-type separate tables for your attributes' values (maybe some indexing might be applicable in that case, though with MySQL's limitation to one index per query per table even that's somewhat dubious).