Designing a database for a site that stores content from multiple services?

I'm building a site that implements David Allen's Getting Things Done that pulls in your email, Facebook newsfeed, tweets from those you follow on Twitter, and more services are planned. The problem is that I'm not a DBA, and I'm not sure how to design the database so that as I add features to the site, I won't have to artificially corrupt people's raw data for the purposes of storing it (for example, I want to add the ability to get RSS feeds sometime in the future, but I'm not sure how I'd do that without making a mess).

I've put down my initial ideas using DBDesigner 4, below, you'll find the diagram and the SQL.

A few notes to help clarify clarify things.

• The Accounts table is for storing authentication tokens and such for facebook, twitter, and such.

• The messages table is incomplete.

• The password fields in emailconfiguration and users are encrypted, users with a one-way hash, emailconfiguration with a two-way.

• I'm using a MySQL database using the InnoDB storage engine on Amazon RDS.

• Each project may have one context associated with it.

• Each message may have a project and context, but it's not required.

• The imap, smtp, and pop3 tables exist to remove duplication within email configuration.

• queries to this database are generated by Korma, a clojure library.

Can someone please point me in the right direction? I'd also be willing to look at using a NoSQL database if suggested. Thank you for your time and consideration.

Here's the SQL create script just in case anyone wants to see it.

```
CREATE TABLE Pop3 (
domain VARCHAR NOT NULL,
host VARCHAR NULL,
port INTEGER UNSIGNED NULL,
ssl BOOL NULL,
PRIMARY KEY(domain)
)
TYPE=InnoDB;

CREATE TABLE Imap (
domain VARCHAR NOT NULL,
Host VARCHAR NULL,
port INTEGER UNSIGNED NULL,
ssl BOOL NULL,
PRIMARY KEY(domain)
)
TYPE=InnoDB;

CREATE TABLE users (
Username VARCHAR NOT NULL AUTO_INCREMENT,
email VARCHAR NULL,
password_2 VARCHAR NULL,
activation VARCHAR NULL,
is_act

Is there a reason why you have no unique constraints in your database? What happens if somehow you get two rows with configuration data for the same email address? How do you determine which one to use?

I think the one piece of real advice I can give you is look at keys/functional dependencies and add as many unique constraints as make sense. it is far easier to drop unique constraints later than it is to add them.

StackExchange Database Administrators Q#15920, answer score: 2