What databases do the World Wide Web's biggest sites run on? [closed]

Answer 1

Digg

• MySQL (Relational Database) for scaling out reads
• MemcacheDB (Key-Value Store) for scaling out writes

Both data stores are distributed across multiple servers.

Digg stats:

• 30M users
• 26M uniques per month
• 2 billion requests a month
• 13,000 requests a second, peak at 27,000 requests a second.

Sources:

• http://www.krisjordan.com/2008/09/18/joe-stump-scaling-digg-and-other-web-applications/
• http://highscalability.com/scaling-digg-and-other-web-applications