Like Twitter, Digg is moving from MySql to Cassandra.

Digg is moving away from MySql to a “NoSql” solution due to difficulties in building a “high performance, write intensive” application said John Quinn, VP of engineering in a recent blog post.

Growth has forced us into horizontal and vertical partitioning strategies that have eliminated most of the value of a relational database, while still incurring all the overhead

Most of Digg’s functionality has been reimplemented using Cassandra as it’s NoSql datastore. Digg previously ran experiments on their live site, which you can read more about here, replacing a high scale MySql system with a Cassandra alternative.

Digg has also made it’s own enhancements to Cassandra. “We’ve made massive performance improvements: increased comparitor speed, added better compaction threading, reduced logging overhead, added row-level caching and implemented multi-get capability. We’ve also implemented native atomic counters using Zookeeper” he says.

Quinn also mentions says “We’ve tested and improved the operational capabilities of Cassandra, upgrading its Rackaware capability, added slow query logging, improved the bulk import functionality and implemented Scribe support for improved logging”.