Bret Taylor on how FriendFeed decided to scale their datastore.

Lots of projects exist designed to tackle the problem storing data with flexible schemas and building new indexes on the fly (e.g., CouchDB). However, none of them seemed widely-used enough by large sites to inspire confidence. In the tests we read about and ran ourselves, none of the projects were stable or battle-tested enough for our needs (see this somewhat outdated article on CouchDB, for example). MySQL works. It doesn’t corrupt data. Replication works. We understand its limitations already. We like MySQL for storage, just not RDBMS usage patterns.

After some deliberation, we decided to implement a “schema-less” storage system on top of MySQL rather than use a completely new storage system. This post attempts to describe the high-level details of the system.