Coursera

Each month Coursera database servers answer 10 billion SQL queries

Coursera is a for-profit educational technology company offering massive open online courses (MOOCs) founded by computer science professors Andrew Ng and Daphne Koller from Stanford University. Coursera works with universities to make some of their courses available online, and offers courses in physics, engineering, humanities, medicine, biology, social sciences, mathematics, business, computer science, and other subjects. Coursera has an official mobile app for iPhone and Android

Courses

The website provides free online courses including Humanities, Medicine, Biology, Social Sciences, Mathematics, Business, Computer Science, and others. Each course includes short video lectures on different topics and assignments to be submitted, usually on a weekly basis. In most humanities and social science courses, and other assignments where an objective standard may not be possible, a peer review system is used.
Web forums are provided for courses, and some students also arrange face to face study meet-ups using meetup.com, or online meetups. However, the Coursera Honor Code prohibits copying answers, therefore the discussion should not exchange answers but should practice a healthy debate

IT infrastructure

Coursera runs the nginx web server on the Linux operating system on the Amazon Web Services platform. Data is stored in Amazon S3, and site search is handled by CloudSearch that indexes over 4.3 million documents on the site. Each month Coursera’s database servers (running on RDS) answer 10 billion SQL queries, and Coursera serves around 500 TB of traffic per month

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