Re^2: RFC: OtoDB and rolling your own scalable datastore

[arbingersys]

I would say because you get more out of an RDBMS than merely relational data structure. You also get:

• High level and powerful query language (OtoDB uses this feature rather extensively)
• Optimized storage and data retrieval engine (data indexes, etc)
• A well-known paradigm
• Additional power at the data server level like views, or clusters

An RDBMS does more than just store and retrieve datasets. It also prepares data based on SQL commands you send it. Maybe I'm wrong, but it seems that memcached is just a storage mechanism. I.e. your code has to handle sorting/filtering. With an RDBMS you can ask the data servers to do this.

There are probably some other reasons too, that I'm not thinking of. I should also point out that you are in fact using one relational feature, that of one-to-one relationships.

[chromatic]

You're not going to get 65k queries per second out of an RDBMS if any of those queries have to do JOINs, and you're not going to put Varnish in front of it to speed it up even further. You can do that with memcached and CouchDB, for example.

I'm by no means suggesting that there's anything wrong with JOIN, or that every persistent data storage needs to do what eBay or MySpace or Amazon.com does. Yet by the time your problem is that your database is a bottleneck, slapping something on top of the database doesn't seem like the right approach.

(Similarly, I have the strong belief that if ActiveRecord could run on something other than an RDBMS, everyone would be a lot happier.)