As I know, many scripts, such as serial downvote detecting, tag clearing, data caching, run at 3am, but why they run at 3am instead of 0am or at other period? Is it because the system is not busy at 3am? Or there are security reasons for that?

2 Answers 2


Most likely because 3 AM is the least busy hour on the servers, both web and database.

This SEDE query proves it:

Along with 2 AM, those are the hours with least questions and answers being posted, which makes the major part of database activity as far as I can tell.

  • Good work in distracting them, alcolite #152859. They don't need to know that the number was chosen because it represent the three pony races.
    – SPArcheon
    Jan 29, 2016 at 19:03
  • @SPArchaeologist No love for alicorns, eh?
    – Keen
    Feb 5, 2016 at 16:57
  • @Keen sure about it? ;) Feb 5, 2016 at 17:06
  • @Keen, they were going to, but then they decided they didn't want to promote alicorn OC users.
    – SPArcheon
    Feb 7, 2016 at 19:16

I'm not particularly into the schedule SE has to operate their site and databases, but to me it seems that first some more critical jobs run, like backups, other scheduled tasks, etc. If that is all safe, the serial voting script and some other tasks are ran. Usually you reserve some time slots to do specific (and sometimes occasional) tasks. The 3AM slot is reserved for the site scripts to run.

To me, it seems strange it would have a security reason, since all sites are online 24/7. It doesn't matter to them when they run it.

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