Learn to code site Code.org loses student work due to index bug

Cracks limit of 32-bit table size without realising it. Back to the books, guys?


Learn-to-code site Code.org is apologising to its students after being caught by a database table maxing out, and dropping progress for an unknown number of participants.

In its mea-culpa blog post, the group says it was burned by a database table with a 32-bit index.

>“The way we store student coding activity is in a table that until today had a 32-bit index. What this means is that the database table could only store 4 billion rows of coding activity information.”

And guess what? Yup: the site cracked the 4 billion barrier without even noticing it was about to become an issue.

The organisation has since rebuilt the table as 64-bit, but in the meantime, some students' work was lost, while others will have to wait until their progress is restored from another database.

The good news is that only a little more than an hours' worth of student data was lost on Friday, from 9:19am to 10:33am Pacific time on January 20.

For students enrolled in the organisation's “Course 1-4, Accelerated Course, CS in Algebra, and Hour of Code Activities”, it's not all bad. Their work is stored in a different database, and will re-appear just as soon as they get it restored.

Alas, others are not so lucky: if you were working on “CS Principles and CS Discoveries:” courses, the outage means there's an hour of your life that you won't get back. ®

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