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Epoch Time Bug Causes Facebook To Congratulate Users On 46 Years of Friendship (gizmodo.com)

Posted by Soulskill on from the somebody-missed-an-edge-case dept.

An anonymous reader writes: A bunch of Facebook users received mysterious messages yesterday congratulating them on 46 years of being friends with somebody on Facebook. An astute observer may note that Facebook hasn't been around for 46 years. An even more astute observer might note that 46 years ago yesterday would be 12/31/1969 — easily recognizable as value '0' in the Unix Epoch with a time zone adjustment. A Microsoft engineer posits that the messages were sent because of how Facebook implemented its congratulatory messages. Many people were Facebook friends when the feature was rolled out, and instead of finding or estimating the date they became friends, Facebook simply set that database value to '0'. When the script fired to send those messages, it grabbed that value expecting a time, and interpreted the 0 accordingly. "The developer who wrote the "friends with since" memories algorithm should have added a case WHERE friendsWithSinceDate != '0' or something along those lines."

2 of 108 comments (clear)

  1. NULL is there. Use it! by DahGhostfacedFiddlah · · Score: 3, Interesting

    I don't understand people who prefer to use magic numbers over NULL, but there appear to be many.

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    Last post!
  2. Re:NULL is there. Use it! by Anonymous Coward · · Score: 2, Interesting

    NULL is a special case in any SQL database. If you try to check if something is equal to NULL, you will always receive false. Even NULL = NULL is false. That forces you to specifically check for a NULL value using IS NULL instead of accidentally bumping into correct functionality, but having things inexplicably break later on.

    And the fact is, this Facebook bug is probably caused by how most data connector libraries interpret a NULL timestamp in MySQL (IIRC, FB uses a heavily-modified variant of MySQL). They're technically NULL, but the connector libraries always return it as 1969-12-31 00:00:00.000. (Which is retarded, because the time component is all sorts of stupid and broken in that value. If they were going to make it one-step-before-zero, it would have a time of 11:59:59.999. And also because NULL should be NULL, not a value that might be valid to other types of code.)