Last time I checked either MS SQL, MySQL, or Oracle were the fastest SQL Databases. I know their results always show themselves as the fastest but I'm not really concerned with it. What I want to know is how the data is arranged and how it is accessed afterwards.

So, if someone could offer a technical or non-technical explanation of how they store/access this data I would be grateful. Hit me with any of it.

Secondly, how does an SQL database's speed compare to using XML files for storing data in a structured way? I often wonder wether or not I want to try making a complex website without SQL and going all XML. No proprietary **** to deal with for your data. Just ship it out however you want.

Any thoughts would be appreciated! Thanks ahead of time.

Well to answer the question of is XML as fast, a very small xml "may" be faster, but anything dealing with larger record sets is better off in a db. Db's can index the data, meaning it basically keeps a record of where data falls in the tables, so it can find it faster, without having to look at every row.