Today I learned that the total number of tweets ever made on Twitter is roughly 4x the total number of posts ever made on Tumblr.
The number of database servers they have is far, far more than 4x, and ditto for the number of staff members working on their databases. Also keep in mind the average Tumblr post is quite a bit larger than a tweet.
Not knocking Twitter by any means — their work is extremely impressive, especially their open source contributions. But given visibility into the raw numbers, I’m especially proud of the database work my former teams (tiny, tiny teams!) accomplished at Tumblr.