Notes on CouchDB, a distributed document DB in Erlang

Yikes, where to start.

"Databases store data to disk. Thats all what 90% of us use them for. They are essentially elaborate hash tables backed by a disk drive."

Sure, if you don't need indices or transactions.

"a disk failure is still a major disaster. Even if you have backups, even if you have replication, there will be downtime and manual labor while a new master server is established."

If you use a dual-port, dual-controller RAID 10 with hot spares, you'll never even notice a disk failure. (No wonder the SmugMug people are so smug.) But I admit replication is a great solution for people who consider their time to be a sunk cost.

"Databases never put your 10-20 commodity server boxes with all their spare disk space to use."

At least this is true (for now). Given that Web 2.0ers apparently don't care about most database features anyway, maybe HBase will solve this problem.

From the CouchDB Wiki:

What it is not

A relational database.

A replacement for relational databases.

An object-oriented database. Or more specifically, meant to function as a seamless persistence layer for an OO programming language.