Simon Willison’s Weblog

A write-ahead log is not a universal part of durability (via) Phil Eaton uses pseudo code to provide a clear description of how write-ahead logs in transactional database systems work, useful for understanding the tradeoffs they make and the guarantees they can provided.

I particularly liked the pseudo code explanation of group commits, where clients block waiting for their commit to be acknowledged as part of a batch of writes flushed to disk.