February 24, 2010, 12:42 PM — Ryan King, an engineer at Twitter, today told the blog MyNoSQL that the social networking company plans to move from MySQL to the Cassandra database for what he called its resilience, scalability and large community of open-source developers.
"We have a lot of data, the growth factor in that data is huge and the rate of growth is accelerating," King said in the interview posted on MyNoSQL.
San Francisco-based Twitter currently uses a cluster of MySQL servers with a memcached caching system that "is quickly becoming prohibitively costly (in terms of manpower) to operate. We need a system that can grow in a more automated fashion and be highly available," King told MyNoSQL.
The number of daily tweets has grown more than twenty-fold in the past year, from about two million a day in January, 2009 to nearly 50 million a day last month.
Twitter has nevertheless improved its uptime significantly in the last 12 months. The site was up 99.72% (down 23 hours, 45 minutes) in the last 12 months, according to Web monitoring firm, Pingdom. In 2008, according to Pingdom, Twitter was down for 84 hours, worst of 15 major social networking sites.
Twitter hopes that deploying the Apache Software Foundation's Cassandra database will improve that record further.
First developed by Facebook to augment its MySQL installation, Cassandra is a lean Java-based data store, that shucks the overhead of conventional relational databases. The technology is similar to that offered in other emerging NoSQL databases like MapReduce and Hadoop,
For skilled programmers, the so-called NoSQL databases can boost performance and scalability, which has made them attractive to the consumer Web world.