Pastebin design - Mnesia tables

I have started to design the tables for this.  The main goal is simple: make it easily extendable.  That is to say I want to make it so I can easily develope it incrementally and add things to it that I didn’t think of before.  But that should be obvious to any developer.  Given the spec of my previous post, here is the beginning of the database.

Table:
paste - This is the table that will hold the actual pastes. 
pid | text | annotation | language | date

pid - unique id to identify a paste
text - the actual text
annotation - any annotation the paster wants to include
language - Plaintext/C++/Erlang, etc
date - when they pasted it


highlight - cache of pastes that have been put through the source highlighter
pid | text | last_viewed

pid - the same as paste.pid
text - result of being put through the highlighter
last_viewed - to keep track of when the entry should be removed

threads - paste threads
tid | [pid]

tid - the unique id for a thread
[pid] - list of pid’s


I decided to have the thread table just contain an id and list so you don’t have to do a bunch of queries to get every paste in a thread.  This way a paste can be part of multiple threads (Although I don’t see when this will ever happen).  The paste table contains, I think, the minimalist amount of data in order to be useful.  Using a highlight table means we can store, if we want, every single paste with a highlighted copy of the text, or just a few and use it as a cache style system.  Later on we can also add the ability to associate a paste with an irc channel or a user if we wish to track that sort of information.

I’m not sure how to generate unique id’s in mnesia.  In a SQL database I would use a serial data type but I am unsure if mnesia supports this functionality.  If not I suppose I could use newref maybe?  I need to be able to convert it to a string to make url’s, and also be valid between restarts.

As I think about it, I guess serials are just implemented as a table and store the integer in there, I can implement that in mnesia I suppose.  It just needs to have some sort of get_and_increment functionality so two proceses don’t get the same idea.  If anyone has any ideas on how to implement this let me know.  Bear in mind I have not looked at the mnesia documentation yet and am just brainstorming, so it is quite possible the solution is incredibly simple.

Next step - determine what pages pages will be needed.